1 15 3 https://www.nal.usda.gov/exhibits/speccoll/files/original/8be61ef0f3b84c3d15689842a3d534e2.pdf 9177445599cffcffcd4dd2ac04312824 PDF Text Text Item ID Number °0882 Author MacLeod, Colin M. Corporate Author Panel on Report/Article Title Re Herbicides of the President's Science Advisory P°rt on 2,4,5T: A Report of the Panel on Herbicides of the President's Science Advisory Committee Journal/Book Title Year 1971 Month/Day Color March 2 D Number of Images ^ DOSCrlptOn Notes Friday, March 16, 2001 Alvin L. Young filed this item under the category "Human Exposure to Phenoxy Herbicides and TCDD" Page 882 of 967 �REPORT ON 2,4,5-T A Report of the Panel on Herbicides of the President's Science Advisory Committee QFFIHF OF JUE RRESIDENT OF SCIENCE AND TECHNOLOGY MARCH 1971 �REPORT ON 2,4,5-T A Report of the Panel on Herbicides of the President's Science Advisory Committee EXECUTIVE OFFICE OF THE PRESIDENT OFFICE OF SCIENCE AND TECHNOLOGY MARCH 1971 �For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D. C. 20402 - Price 40 cents �MEMBERS OF THE PANEL DR. COLIN M. MACLEOD, Chairman, New York University Medical Center, Now York, Now York DR. JOHN D. BALDESCIIWIELER, Stanford University, Stanford, California DR. NYLE C. BRADY, Cornell University, Ithaca, New York DR. EMMANUEL FARHER, University of Pittsburgh, Pittsburgh, Pennsylvania DR. PAUL KOTIN, National Institute of Environmental Health Sciences, Durham, North Carolina DR. BRIAN MACMAHON, Harvard School of Public Health, Boston, Massachusetts DR. NORTON NELSON, New York University Medical Center, New York, New York DR. L. DALE NEWSOM, Louisiana State University, Baton Rouge, Louisiana DK. JOHN W. TUKEY, Princeton University, Princeton, New Jersey DR. JAMES G. WILSON, Children's Hospital Research Foundation, Cincinnati, Ohio * * * * DR. EDWARD J. BURGER, JR., Staff, Technical Assistant, Office of Science and Technology, Executive Office of the President, Washington, D.C. DR. DAVID PIMENTAL, Consultant, Office of Science and Technology, Executive Office of the President, Washington, D.C. iii �THE PRESIDENT'S SCIENCE ADVISORY COMMITTEE EXECUTIVE OFFICE BUILDING WASHINGTON, D.C. 20506 March 2, 1971 The publication of this report on the herbicide, 2, 4, 5-T, symbolizes an area of public policy decision-making in which science and, hence, scientists have a large responsibility. The report itself is a landmark. It examines in detail the scientific considerations leading to policy judgments about a pesticidal chemical. The foresight of Dr. Lee DuBridge, Science Adviser to the President at the time this review was initiated in October 1969, is commendable. The Government agencies charged with responsibilities for regulating pesticides and for overseeing the integrity of the public's health, chose a course of regulatory action in October 1969 which restricted some uses of 2,4, 5-T. This action was taken as a result of a new and unexpected research finding which emerged from experiments sponsored by the Government. At that time, Dr. DuBridge perceived the need for a thorough and critical review of all of the scientific information available on the herbicide -- including that dealing with biological properties and human health. Importantly, the report's major recommendations already have been adopted by the appropriate Government agencies and specific actions have resulted. The original experiments were confirmed and extended by later research. A potent impurity, a family of dioxins, has been the subject of several research projects. These have taught us more about the herbicide's physical stability, environmental persistence and biological properties. A recommendation for a legislative mechanism to restrict temporarily the use of a pesticide on the occasion of an unexpected research finding implicating it as a health hazard (while further confirmatory research is performed) is reflected in the Administration's proposed legislation on pesticide regulation. Although the report is concerned with highly technical matters, it does allude to some policy issues. It compares the scientific evidence available, and considered adequate, at the time of first registration of �2, 4, 5-T with the much greater level of scientific understanding demanded today. The Panel found evidence of measurable benefits from the use of 2, 4, 5-T but there was simply very little information that could be used to assess risk. Based on its experience in evaluating risks and benefits on the basis of incomplete information, the Panel cautions that judgments on benefits and risks associated with pesticidal chemicals require an unusual measure of prudence to assure that the public is neither subjected to undue risk nor unnecessarily denied the benefits of valuable chemicals. The report does not speak in particular to the regulatory actions taken by the Government on 2,4, 5-T (although I am satisfied that the review complements them in every respect). If any of the Government actions appear divergent from these recommendations,' the divergence is consistently on the side of prudence and avoidance of the possibility of hazard to human health, and this is as it should be, for Government must act on the side of prudence. It provides those of us concerned with pesticides, their economic value and utility, their negative effects on the environment, and their other biological effects, with an excellent case study. The principles brought out in this study will be useful in dealing with other pesticides, and indeed with chemicals of other kinds. Edward E. David, Jr. Chairman �CONTENTS Page Summary and Recommendations. Introduction Chemistry, Synthesis Formulation , Solubilities Purity of Technical Grade Material Analytic Methods Chemical Stability of 2,4,5-T Uses and Significance Production Uses 1. Domestic 2. Military Cost Sharing Program Toxicology Acute Toxicological Investigations Occupational Experience National Cancer Institute Screening Study Reports of Birth Defects Toxicity of Dioxin Teratogcnesis Testing Summary of Experiments Residues of 2,4,5-T in the Environment Residues of 2,4,5-T resulting from recommended uses in the United States Residues of 2,4-D and 2,4,5-T resulting from recommended uses by the military for defoliation Some Ecological Effects 1 8 10 10 11/ 12 }3 17 21 25 26 26 26 32 36 38 39 42 42 47 47 49 50 54 54 60 65 vii �SUMMARY AND RECOMMENDATIONS Summary This review of the herbicide, 2,4,5-T, began with mi examination of the results from an experimental screening study which implicated it as a potential teratogen. It quickly became evident that examination from such a restricted basis was inadequate. Therefore, the Panel decided to study more broadly important aspects of 2,4,5-T, including details of its chemistry and purity, its domestic uses and their relative importance, the military significance attached to 2,4,5-T as a defoliant, residue levels (in order to estimate probabilities of human exposure), general effects on the environment, as well as its toxicity. In examining the toxicity of 2,4,5-T, the Panel reviewed the information available from the literature (as well as some unpublished documents) which had been considered in the past in establishing policy decisions for the various uses to which this pesticide had been put. Selection of 2,4,5-T as an example for detailed examination has had a number of advantages. There has been an extensive history of use and experience. 2,4,5-T was first registered on March 2, 1948, by the Amchem Products Company, Ambler, Pennsylvania. Since that time considerable information on its properties and uses has accumulated. Furthermore, it has been the subject of reviews by others in the past. Finally, the problem which brought it to the Panel's attention., suspicion of teratogenieity, appears to bo a relatively manageable problem in contrast to many other biological effects, notably tumor production and gene-tic alterations. This is important since the recommendations which follow can be made with a degree of confidence that cannot bo applied to carcinogenic or mutagenic effects. For example, the dose-response characteristic of teratogens is generally restricted to a relatively small range of dosage. Accordingly, a threshold below which no effect would be expected can bo assigned with more certainty. Experiments to determine this range of values can be performed in a relatively short time and do not require vcr}- large numbers of animals. The Panel is gratified that some of its recommendations are already being carried out, especially further experiments to confirm and ex1 420-165 O - 71 - 2 �tend the results of the original screening that indicated 2,4,5-T to be teratogonic. In considering the, chemistry of 2,4,5-T, our attention was drawn to impurities which can result from the manufacturing process. Particular attention was focused on a single impurity, 2,3,7,8-tetrachlorodibcn/o-p-dioxin, which occurs in commercial preparations of the herbicide in highly variable amounts unless particular care is taken .to exclude it. This impurity is cxtrcmcl.y toxic. Its amount depends upon variations in the reaction conditions. Other dioxins can be formed from various impurities in the starting materials. The dioxin impurity came to particular attention when the U.S. herbicide industr}' was asked to produce larger quantities of 2,4,5-T during the middle 1960's. However, its presence as an impurity and certain of its acute toxic effects had been known since 1957. Its concentration in commercial 2,4,5-T has been greatly reduced in the past year or so. Analytic methods available for 2,4,5-T are accurate and reliable. With the possible exception of citrus fruits, determination of residues in food has not presented a serious analytic problem. 2,4,5-T is relatively labile in nature. Residues in soils and water are not persistent except under unusual conditions. The herbicide is not stored in plants or animals to a significant extent. Production of 2,4,5-T in the United States rose rapidly between 1960 and 1968. Civilian use, most of which is for clearing of range land and rights-of-way and for treatment of pastures, declined about 50% between 1964 and 1966. Military use of 2,4,5-T as a defoliant, expressed as number of acres sprayed, rose sharply between 1964 and 1967 but has declined since then. Although accounting for only a small amount of the total usage of 2,4,5-T, its place in control of aquatic weeds is significant. There is a small but important list of agricultural uses where 2,4,5-T is applied to food crops. Potential human exposure is recognized in this direct application to food crops, in range and pasture lands grazed by domestic meat and dairy animals, and possibly, in water supplies derived from treated waterways and streams. The economic importance of the various uses is considerable, but is very much less than that of 2,4-D. Substitution of 2,4-D for 2,4,5-T can be made for certain uses. Defoliation, using mixtures of 2,4-D and 2,4,5-T, has been employed in Vietnam since 1962, more intensively since 1967. Although not rigorously demonstrated, its military usefulness has been considered to be very high. The background of toxicological information on 2,4,5-T is thin. Most of the animal studios have; been concerned with acute toxicity (single doses or repeated doses for short periods of time). Based on these experiments, the acute toxicity of 2,4,5-T was found to be low. Little is known of the details of the metabolic handling of the material although rapid excretion in the urine seems to be the rule. �The screening study supported by the National Cancer Institute on the toxicity of certain pesticides and other important industrial chemicals marks an important advance in toxicological testing in that the tests were designed to detect carcinogenic, teratogenic and mutagenic potential. The preparation of 2,4,5-T used in those tests was shown to bo teratogonic in both rats and mice. There was no evidence that it was carcinogenic. While this study had a number of limitations which qualified its usefulness, the teratogenic results were sufficiently convincing so that the Panel urgod, early in its discussions, that they be repeated and extended using better characterized preparations of 2,4,5-T. Analysis of a sample of the 2,4,5-T preparation used in the original teratogenesis study revealed a dioxin level of about 27 ppm. Such a considerable contamination by this highly toxic material raised the question as to whether the teratogenic effects observed were caused by 2,4,5-T itself, by the dioxin impurity or by other impurities in the commercial preparation tested. The Panel was aware of press reports of increased birth defects in Vietnam attributed to the use of defoliants. The lack of accurate epidemiological data on the incidence and kinds of birth defects in the Vietnamese population before or since the military use of defoliants precludes any estimate as to whether an increase in birth defects has occurred. Calculations of potential human exposures from sources such as drinking water or direct fallout make this appear unlikely (though theoretically possible). A review of the environmental effects of 2,4,5-T on nontargct organisms reveals few harmful consequences of its recommended uses. Induced changes in vegetation arc followed by alteration in numbers of wild animals. Accelerated erosion of soil may follow the killing of brush with herbicides but mechanical removal causes greater erosion. Recommendations I . Further studies. a. The animal experiments which raised the (juestion of the teratogenic potential of 2,4,5-T should be extended to include a wider range off doses administered to non-inbred strains of animals and to larger numbers of animals. b. The importance of the impurities in 2,4,5-T as potential health hazards should be ascertained. Recent experiments designed to distinguish between 2,4,5-T and the dioxin impurity have suggested that both the herbicide and the dioxin are potential teratogens in some experimental animals. However, experiments necessary to establish this answer have not been performed. In addition, there may bo additional impurities in commercially prepared phonoxy herbicides which may be biologically active. �c. The metabolism of 2,4,5-T in humans should be determined and compared to that in experimental animals. 2. The level oj dioxin, a recognized impurity in 2,4,5-T should be rigorously controlled and limited to not more than 0.5 ppm. A reduction to not more than 0.1 ppm should bo urged. Several polychlorinatod dioxins have been found to bo highly toxic and capable of eliciting toratogcnie effects, though they vary widely in toxicity. Since they may reach the environment from multiple sources, control over known sources should bo exercised to the extent possible. 3. A decision to restrict the use of 2,4,5-T should not be based on the isolated finding oj toxicity but on the expected exposure follou/ing recommended use in relation to dose response effects. In general, the imposition of restrictions on the use of a pesticide would appear to bo a function of two factors, the potential for human exposure and the nature of the toxic effects. For example, if carefully documented residue information points to little likelihood of exposure, the risk of adverse effects would be less significant than if exposure were widespread. The Panel found no evidence to suggest that significant residues would result from recommended uses of 2, 4, 5-T on food crops. It is possible for residues to occur in tissues of animals grazing on recently treated pastures and range; land. In fact, the only residues which have been identified in the total diet studies have occurred in moat and dairy products. However, the few cases in which residues have been discovered have all been at levels well below those which would be expected to result in significant toxicity for man. The experimental finding oj teratogenesis requires further elaboration before it can be interpreted as a human health hazard. The risk of teratogenic effects should bo placed in perspective. Teratogenesis induced by chemicals is a fetal response at a particularly sensitive period in embryonic development to lower doses of the chemical than are acutely toxic to the mother. Birth defects can be produced in the embryo through many mechanisms of injury when the agents are administered during critical periods of organ ogcnosis. It is generally held that by careful choice of dosage, which may bo close to the acutely toxic dose for the mother, most chemicals might be shown to be teratogenic in animals. For a variety of reasons, it is not possible to translate directly the results of experiments in animals to man. There are differences in sensitivity which arise from differences in metabolism. Comparative metabolic studies in man and animals, therefore, are important in interpreting toxicity for man. The important consideration is not only the dernonstation of tcratogenicity, which may occur with many chemicals at scclotod dosages, but the estimation of the likelihood of teratogenic effects with the amounts likely to bo ingested incident to recommended �use. To restrict or ban usage of chemicals oil the basis of demonstration of toratogonicity at close levels which far exceed actual or expected exposures is unreasonable and could well deny usage of chemicals whoso benefits far outweigh risks. 4- Registrations qf 2,4,5-T for uses on pastures and range lands should be treated as registrations for food crop uses. It is possible for residues of 2,4,5-T to occur in milk and tissues of animals grazing on land recently treated with 2,4,5-T. To date, meat and dairy products have been the only food products in the total diet studies that contained measurable amounts of 2,4,5-T. Uses on range and pasture land should be included in registration for use on food crops. 5. Monitoring oj 2,4,5-T residues should be significantly expanded, especially for meat and milk. In sampling meat and milk, special attention should be given to geographic areas where treatment of pastures and range lands with 2,4,5-T is most common. The 2,4,5-T residues that may occur in moat and milk of animals allowed to graze on pastures and range lands treated according to current recommendations should also be restudiod. 6. As new information is developed on pesticides, it should be disseminated promptly to individuals and organizations that are legitimately concerned as manufacturers, formulators, users and scientific investigators. The ease of 2,4,5-T is illustrative of inordinate delay in making available new research information as it became known. The screening study of pesticides which was carried out by Bionotics Corporation under contract with the National Cancer Institute was completed about August 1968. It was 14 mouths later when the Government announced its coordinated actions on restricting the use of 2,4,5-T It was only after an additional several months that the detailed data of the screening study were made publicly available. A centralized mechanism for handling and disseminating new information about pesticides could help alleviate this problem. 7. A mechanism should be established for restricting the, use oj a registered pesticide temporarily on the basis of information which implicates the chemical as a possible health liazard pending tlie collection of more definitive information. If a pesticide is already in established use, the decision is particularly difficult. Long established use inevitably implies a dependence upon it by the consumer and a corresponding reluctance by the manufacturer to withdraw it from the market. At the present time, a registration may be held in abeyance only by cancellation or suspension. Because of the serious import of these actions they arc put into effect with considerable reluctance. They were not designed for situations such as the present with respect to 2,4,5-T where temporary withdrawal from use, without cancellation or suspension of registration, might have been a more appropriate �action. Such an alternative course of action is not possible under present regulations. There is need for a mechanism whereby the use of a pesticide or other chemical that may affect human health can be temporarily restricted or held in abeyance. Such action would permit the gathering of more definitive information in time for sufficient consultation to permit a decision that would protect the public health and not impose an undue economic burden on the producers, marketers, and users of a product. Coincident with the imposition of restrictions on a pesticide, a mechanism should be available for informing and educating pesticide users and applicators so as to make them more responsible agents. It is recognized that a change in the law governing pesticides would be necessary to accommodate this mechanism of a temporaiy restriction. 8. There is an urgent need for a focus of responsibility in D/IIEW to coordinate and monitor the toxicity and health activities related to eftects of pesticides. Information about the health effects of a pesticide derives from a variety of sources including occupational exposures, residue monitoring, toxicological investigations, clinical experience and epidemiological studies. In the past, there has been no single focus within D/HEW which has been concerned with all of these sources of data and, more important, which has had the authority and responsibility to coordinate new investigative initiatives. The new Advisory Committee on Pesticides to the Secretary of D/IIEW can bo expected to servo as a source of export advice but cannot fill the essential need for a focus of responsibility and authority at the level of the Office; of the Secretary. Consideration of the functions to be fulfilled and the resources available; suggests that this responsibility should bo assigned to the Assistant Secretary for Health and Scientific Affairs because the various components of D/IIEW concerned most with aspects of the health effects of pesticides report directly to him (National Institutes of Health, Food and Drug Administration, National Communicable Disease Center, Environmental Health Service).* 9. Information provided in applications for registrations of pesticides should take into account not only the pesticide for which registration is sought but should identify other substances including vehicles used in formulations, "inert" ingredients, and impurities. Investigation of the synthesis of 2,4,5-T and examination of the manufacturing process revealed that an extremely toxic impurity, 2,3,7,8-tctrachlorodibcnzo-p-dioxin, present in variable amounts in 'Since this report was written, the President established, through Reorganization Plan, tho Environmental Protection Agency which is to bo responsible for broad areas of regulation covering environmental matters. The Environmental Protection Agency will also have the eapacity to carry out some research under its name. Hence, we recognize that some of the elements of coordination recommended in this section will be accommodated by this new agency. �commercial preparations of 2,4,5-T, m&y account for some of the toxicological characteristics assigned to 2,4,5-T itself. The presence of this impurity was recognized as early as 1957. However, the importance of this impurity was not generally recognized in the United States until after 1964. It appears logical that greater specific^ in identifying the components and properties of the mixture of materials which are registered under a single name would increase the probability of identification of potentially toxic substances. 10. Registration procedures should be based on toxicological studies of the particular compounds to be registered rather than extrapolations from studies on related compounds. Toxicological studies provided as information in behalf of 2,4,5-T registration were performed on a variety of related compounds (the free acid, several types of esters and a variety of salts). Results of these tests were regarded as being interchangeable and applicable to the related compounds. There is evidence to caution against this concept. The thorough testing of isomors, esters, salts, and related compounds is a very large and expensive task. Nevertheless, information about a potential health hazard may be incomplete unless all of the compounds to be used are tested. �INTRODUCTION In 1964, The National Cancer Institute undertook through a contract a screening study of a number of pcsticidal chemicals. Among the results of this screening study was the finding that birth defects could bo provoked experimentally in rats and mice by the administration of relatively large doses of the herbicide, 2,4,5-T. By the time these results wore reported, 2,4,5-T had been in common use as an herbicide for more than 20 years. Further, it had been employed along with 2,4-D as a defoliant in Vietnam since 1962, although in sizeable quantities only since 1967. In October 1969 several agencies of Government moved in a coordinated manner to bring about restriction of the use of 2,4,5-T both within the United States and abroad (1). In terms of domestic agricultural use, restriction was placed on the use of 2,4,5-T on food crops pending the acquisition of further information that might permit the Food and Drug Administration to grant a tolerance. Use as a defoliant in Vietnam was restricted to non-populated areas. For a number of reasons, it seemed wise to explore this issue in some detail. The most important of these reasons, perhaps, was the desire to examine the scientific evidence available to stand behind future policies governing the use of 2,4,5-T and to suggest directions for father experimental research. Accordingly, a panel of experts was assembled by the President's Science Adviser to consider a number of aspects of a variety of herbicides some of which were used as defoliants in Vietnam. The present report represents their review of 2,4,5-T. This review considers topics which arc of concern to those who are faced with policy decisions for 2,4,5-T. Wo hope that it can serve as an example for the consideration of the health effects and safety of pesticides and other chemicals purposefully placed in the environment. A number of issues are raised when the utility and safety of an already existing material is questioned. It is elementary but nevertheless true to say that the issues are complex. In a way, their examination can be compared to following a seemingly endless and continuously brandling program. The subject of how much assurance of safety should be afforded is important. Toratogencsis appears to be a more manageable problem than some other health effects (such as tumor production). Prediction of 8 �safety can probably bo made with reasonable assurance. In addition, experiments to test a suspected substance are reasonably straightforward to conduct. Among other problems, the purity of the chemical became! an issue. In the case of 2,4,5-T separation of biological effects of the principal material from those of the impurities turned out to have unusual importance. For this reason, the resolution and accuracy of analytic methods available and used to detect 2,4,5-T and its impurities had to be evaluated. In ascertaining the probable hazard to man of an agricultural chemical, its toxicity in absolute terms must be related to the probabilities of human exposure. Residue information on 2,4,5-T therefore was explored. Finally, there remains a series of policy questions which arc at least as philosophical as they arc technical, the most crucial one being how wide a margin of safety should a society adopt for itself. The panel also touched on a narrower aspect of this question by posing an additional one. This is the practical problem, in the case of a material already in use, of \\o\v the Government should act in the interim between the time of acquisition of preliminary experimental data which reveal a chemical suspect and the performance of more definitive experiments which establish the risk. REFERENCES (1) Press Release on 2,4,5-T. Office of Science and Technology, October 29, 1960. 420-165 O - 71 - 3 �CHEMISTRY Summary 2,4,5-trichlorophenoxyacotic acid is produced commercially by a process which begins with tetrachlorobcnzcno as starting1 material. Technical grade 2,4,5-T is 90-92% pure acid. One of the important impurities, a poly chlorinated dioxin, results both from impurities in the starting material and as side products of the desired reaction. A largo number of esters and amine salts of 2,4,5-T have, been developed as well as a variety of formulations in order to derive specific; propertics of volatility and solubility. About one-half of this total production can be accounted for by the 2,4,5-T acid and its n-butyl ester. The free acid is practically insoluble in water and, generally, the esters are slightly soluble. The amine salts tend to be more soluble. Among other things, penetration into the soil or leaching is a function of water solubility In general, 2,4,5-T residues can b:> expected to be relatively unstable materials in the environment. They are broken down by microbial action and by sunlight and esters are readily hydrolyzed to the free acid. Available analytic methods for do too ting residues arc quite sensitive. The sensitivity of gas chromatography with microcoulometric detection is about 0.01 ppm (10 ppb). Detection of residues in plant material appears to be uncomplicated by bound or complcxed residues with the possible exception of residues in the peels of citrus fruits. Chemical Synthesis of 2,4,5-T The herbicide commonly known as 2,4,5-T or 2,4,5-trichlorophenoxyacetic acid has the chemical formula: The usual starting material in the chemical synthesis of 2,4,5-T is 1,2,4,5-tetrachlorobenzenc which can be reacted with mcthanol 10 �and sodium hydroxide in an autoclave under high temperature and pressure conditions to give the, sodium salt of 2,4,5-trichlorophcnol: -ci high temperature high pressure CII,OH NaOII Cl ci-<f 01 >-ocn3 -ONa 01 il (2,4,5-trichloroanisolc) [1] 2,4,5-trichloroanisolc is presumed to bo an intermediate in this reaction. The high temperature and high pressure conditions of this step arc also favorable for the production of a variety of other compounds from those starting materials. The choice of the proper temperature and pressure, and the control of these conditions throughout the reaction are critical for minimizing side reactions and henco impurities in the final product. The aqueous trichlorosodium phenoxidc is next reacted with chloroacetic acid under mildly alkaline conditions. —ONa + CICII-COOII (NuOIT) > Cl- This product is then acidified with II2SO^ to produce 2,4,5-T. ci Cl-X \-OCII 2 COONu ci ; > Cl-X Cl \-OCII2COOII Cl [3] The conditions for reactions [2] and [3] are mild compared with those required for the hydrolysis in stop [1J. The acid reacts readily with a variety of alcohols to produce a large selection of esters, arid with amines to produce amine salts. -OCIIaCOOII + ROII > Cl-<f >—OCHjCOOR Commercial Formulations of 2,4,5-T The 2,4,5-T compounds used in commercial spray formulations include the acid, salts, and a wide variety of esters and mixtures of esters. These active components are then formulated with solvents and other ingredients to produce a bewildering array of commercial final products marketed under cryptic trade names. 2,4,5-T formulations arc applied as solids or liquids. The solids usually involve 2,4,5-T esters incorporated with clays, talcs, Fullers 11 �earth, mineral silicates, or fertilizers. Orio of the major hazards in the use of 2,4,5-T is drift of the herbicide into areas where it is not desired duo to volatility of the formulation or drift of line particles in the wind. This hazard is ieduced in one solid formulation for which the active material is deposited on polystyrene spheres with a very narrow and carefully controlled paiticlo size distribution. The liquid formulations require a solvent. Typical organic solvents are kerosene or diesel oil. In formulations that are mixed with water for spraying, emulsifiers and surfactants are necessary ingredients. A truly thorough attempt at estimation of the toxicity of the several commercial preparations of 2,4,5-T should take into account all of the added material, "inert" ingredients, vehicles and impurities. 2,4,5-T is most commonly employed as an ester 01 amino salt. (Table 1). The n-butyl ester is used as a defoliant in Vietnam in a 1:1 mixture with 2,4-D, known as Orange. TABLE 1—Production and value per pound of Major 2, //, 5-T formulations—1967 [Drawn from U.S. Tariff Commission, 24] Production Unit value (1000 Ibs.) por pound ($) 2,4,5-Triclilorphonoxy-acctie acid (2,4,i>-T) 2,4,5-TrichloriJlienoxy-acotic acid caters and sults, total 2,4,5-Trichlorplicnoxy-acctic acid, n-butyl ester 2,4,5-Triehlorophenoxy-acetic acid, iso-octyl ester Allother (2,4,fl-T esters and salts) '-- - 14,552 27,18!) 1!), 422 4, C53 3,114 1.25 0.80 0. 68 1.1C 1.09 Solubilities The solubility of the herbicide compound used may bo important in determining the mechanism by which the toxic material enters the plant. It also determines the natuie of the vehicle to ko used in its dispersion. The free acid form of 2,4,5-T is practically insoluble in water (S). The sodium salt is only soluble to a limited extent (loss than 3%), a fact which piacludes its use in the low volume application technique which has become more and more widely used in recent yoais. The amine salts arc considerably more soluble in water; however, they are somewhat difficult to prepare. Only the triethyl and trimothylaminc salts can be obtained in a concontiato of 4 Ibs. acid oqu'ivalcnt/gal. with satisfactory storage qualities. Furthermore, the marked insolubility of the calcium and magnesium salts of 2,4,5-T which are formed upon dilution with water causes nozzle clogging during application. Therefore, these formulations arc not widely used. Ester formulations are most commonly used as oil-water emulsions. The extent of leaching of various herbicide formulations was tested by applying these in solution to the tops of soil containing tubes. The depth of leaching could in general be compared with solubility. For 12 �example, the amine salt of 2,4,5-T was taken to a depth of nine inches whereas 2,4,5-T itself remains at three inches. Aside from the herbicide itself, leaching of diescl oil, a vehicle1, commonly used in herbicide application, might present a threat to ground water quality. However, Lindin and Muller (cited in 13) sprayed diesel oil at rates of 50, 250, and 500 gal./acre, and after sampling with a tube and leaching with raih water, they found only 1.5-2 ppm of diescl oil in sandy loam above 2.5 inches. Purity of Technical Grade Material Technical grade 2,4,5-T manufactured for agricultural applications typically contains 90 to 92% 2,4,5-trichlorophcnoxyacotic acid, and 8 to 10% impurities. The detailed composition of the technical material given by one producer is shown in Table 3. TAULK 2.—2,4,K-T product composition Percent by weight: Ol.Oil.O 2,4,6-lrlohlorophciioxyacetic acid 0.5±0.1 2,4,5-tricliloTOamsolc 2.0=b0.5 5-mcthoxy 2,4-dichlorophcnoxyacetlc acid 2.0±0.5 2-methoxy 4,5-dichlorophcnoxyacotic acid 0.3±0.1 2, 4, 5-lrichloropliciiol 3.0±0.5 bis-2,4,6-trichlorophonoxyac<)tlc acid 0.3±0.1 2.5-dichloropheiioxyacotic acid 0.2±0.1 S04 0.2±0.1 Sodium salt of 2,4,5-T 0.5±0.2 H20 less than 1 ppm telrachlorodibenz-p-dioxlii (TDD). The 1,2,4,5-tetrachlorobcnzenc starting material for the 2,4,5-T synthesis contains typically 3% other tetrachlorobenzone isomcrs and other chlorinated benzenes. Those impurities can contribute to small amounts of a variety of other chlorinated products including dichlorophenoxyacetic acids and other isomcrs of the trichlorophonoxyacetic acid, although these; products were not listed by the manufacturer as impurities. (Table 3). 2,4,5-trichIoroanisole, OCJIi is proposed as an intermediate in step (1) of the manufacturing process. Incomplete reaction of this intermediate accounts for its presence in the final product. There is also a possibility that the 2,4,5-trichloroanisole intermediate can be hydrolyzcd under the conditions of step (1) to give methoxydichlorophenoxyacetic acid as side products: CHsO 13 �and OCIIj ci 2,4,5- trichlorophenol, on results from the incomplete condensation of the sodium phenoxido with chloroacotic acid in step (2). Bis-2,4,5-trichlorophcnoxyacctic acid, is an important impurity because the chloroacotic acid used in step (2) commonly contains some dichloroacetic acid. The 2,5-dichlorophenoxyacotic acid arises from small amounts of 1,2,5-triohlorobonzene in the tctrachlorobonzono raw material. Some sodium 2,4,5-T and sulfate ions are commonly carried into the product from the acidification (step [3]). The standard assay for technical grade 2,4,5-T is a simple titration to give the acid equivalent of the product. On this basis most manufacturers market a product that has 97 to 98% acid equivalent. Analysis for actual 2,4,5-trichlorophonoxyacotic acid content by gas chromatography is loss commonly given, although a standard method exists. The Department of Agriculture reported that the content of 2,4,5-T was often as low as 85% in commercial materials that meet the 97% acid equivalent specification. (22) Gas chromatography is used to monitor trace impurities in process control for stop (1). The impurities present in any commercial preparation of 2,4,5-T depend strongly on the purity of the starting materials and the reaction conditions. Those can vary among various producers and among batches for a given producer. The detailed processing methods and purification procedures also vary widely among the various producers. The variation in product analysis has not been carefully documented, and the toxicitics of most of the impurities have not been tested. It is not prudent to assume that the combined toxicity of the mixture of materials in one preparation is representative of all of the preparations that arc widely used. 14 �One trace impurity produced in the manufacture of 2,4,5-T has received considerable attention. Tctrachlorodibonz-p-dioxin, commonly known at TDD, C1-, ci-i is produced as a side product under the conditions of step (1). Since this compound is known to bo extraordinarily toxic, the history of the recognition and identification of this impurity is particularly interesting. Elucidation seems to have come from two principal independent sources. The sporadic occurrence of an impurity in specific lots of animal feed in 1957 brought significant losses to poultry farmers in southeastern and central U.S. Chicks were afflicted with hydroporicardium, and suffered gross kidney and liver damage. Empirical tests for the presence of the "chick edema factor" were, announced by the the FDA in 1966 (11). The test used electron capture gas chromatography to examine a fraction of a sample isolated from the fat. The; presence of a specific set of peaks with given retention times indicated the presence of the factor. The empirical tost is used as a screening procedure. When the presence of the factor is indicated by gas chromatography, a chick bioassay test is required for confirmation. The absence of the factor is a requirement of the edible tallow used for making fatty acids that go into food cmulsifiors. The chick edema factor was identified by X-ray crystallography as 1, 2, 3, 7, 8, 9-hoxachlorodibcnz-p-dioxin in 1967 by Wootton of Proctor and Gamble (25) from 4 mg of toxic material extracted from 100 Ibs. of contaminated fat obtained from trade sources. The toxicity of this compound and related compounds was reported by representatives of the Food and Drug Administration in 1968 (11). A clue to the possible origin of the dioxins was suggested in their synthesis by condensation (21). Two molecules of 2, 4, 5-trichlorophenol condense directly to give TDD: + 2IIC1 Two molecules of 2, 4-dichlorophcnol condense to give the dichlorodibonz-p-dioxin, /o\ Cl- and mixtures of various isomeric chlorinated phenols give mixed chlorinated dioxins. 15 �The FDA group reported the following toxicitics: TABLE 3. —After Higginbolhan, et al, (IS). Ecactants No. of Cl atoms In dioxin 2,4-dichlorophenol ......................................... ______ ..... 2 Chlorinated dibcnz-p-dioxin i .......... . ................... . ................... ... 2,4,6-trichlorophonol- ............ . ............. . ....... ____ ........... 4. 2,4,0-trichlorophonol--. ..... . ....... . ......... . ..................... .. 4 2,3,4,6-totracbloroplienol ........ ................................. ____ 6 Pentachlorophenol____...................................... ......... . 8 Eeferenco toxic fat components. ..... ................................ Mixture 1 Chicken embryo bioassay -----------percent mortality 500 0.05 0.25 5.0 1-0 ft.O 3.0 70 100 100 50 100 27 100 Mixed 3 & 4 chloro species. The tctrachloro species, which will be the important product from the condensation of 2,4,5-trichlorophcnol, requires only 0.25 jug for 100% mortality in the chick embryo bioassay. A mixture of the tri- and tctrachloro species was reported in one study to be more toxic than the tetrachloro species alone (12). However, more recent unpublished observations by the same authors have pointed toward a singularly high degree of toxicity of the four chlorine members of the family. The conditions required for the production of the tctrachlorodibcnzp-dioxin, TDD, arc present in stop (1) of the commerical 2,4, 5-T synthesis, so this material can bo present in the original herbicide. Members of the family of dioxins have been recognized in a variety of environmental situations. The origins of those arc not clear in every case (23). The second source of information about the toxicity of dioxin compounds came from observations of occupational exposures in plants manufacturing 2,4, 5-T. These arc reviewed in another section of this report. One of the diseases reported was a particularly refractory form of skin rash known as chloracno. This was also seen in workers involved in the production of other compounds, The first report of chloracno in 2,4,5-T plant workers was in 1957 (H). The authors in this case suggested that the dioxin impurity may have been the factor which caused the chloracne. In 1964, the Dow Chemical Company (6) attempted to increase the production of 2,4,5-T by changing the reaction conditions. Plant operators became affected with chloracno. The Dow Chemical Company closed their facility and, early in 1965, alerted other manufacturers of their problem. The active agent was identified as 2,3,7,8tetrachlorodibcnz-p-dioxin. In addition, an analytical method for its detection was standardized and various methods for removing the impurity were devised. By 1965, sufficient technology was available to allow the manufacture of 2,4,5-T and 2,4,5-trichlorophcnol containing no more than 1 ppm of 2,3,7,8-tetrachlorodibenz-p-dioxin. By 1966, a now Dow plant, conforming to those specifications, was 16 �put into operation. TDD levels in technical grade 2,4,5-T from another manufacturer are listed year by year in Table 4. Dioxin levels in 2,4,5-T currently manufactured are reported not to exceed 1 ppm. TAHLE 4.—History of TDD concentration in technical 2,4,5-T [Analysis or material from one manufacturer] ppm, TDD Date 11 11 8 5 10 11 12 5-32 3-18 1-25 1-25 1058... 1959.., 1960... 1961.. 1902... 1963... 1964... 1965... 1900... 1967... 1908... 1969... Analytical Methods 1. Standard Procedures. A typical method for the analysis of herbicide residues in oil seed crops has boon described by G. Yip of the FDA (27). Tho method involves extraction of 50 grams of oil with sodium bicarbonate solution, acidification, and extraction of the herbicides with chloroform. The herbicide residues in the acid form are then osterified with diazomethanc to produce the methyl esters which are finally analyzed by programmed temperature gas chromatography. Both electron capture and microcoulometric detection schemes are used. The microcoulomotric detector consists of a quartz tube condensation chamber where the herbicide is pyrolyzed at 800° C in the presence of oxygen. The IIC1 formed is carried into a microcoulometric titration cell whore the chloride is titrated with silver ion. Tho sensitivity of this analytical scheme is about 0.01 ppm. A gas chromatogram obtained from cottonseed oil treated with a mixture of seven herbicides each at 0.02 ppm is shown in Fig. 1. The seven herbicides used in this test of the method included: OCHaCOOII OCHiCOOII Clla MCPA 2,4-D COOn OCHzCHzCIIjCOOII OCIIzCOOII CHs 0-CII-COOH -Cl ?,3,6-TBA 2,4-DB 2,4,5-T 17 420-165 O - 71 - 4 �CONTROL 2,3,6-TBA PCP , .* O.OZPPM 2.4.5-TP 2,4,5-T iUPDA ( MCPA ~ ' • 10 12 14 2,4-OB 16 MINUTES FIG. 1—Gas chromatogram of the 0.02 ppm sample of herbicide mixture and a control. Both curves represent 35 g of cottonseed oil.—After Yip (27). All of those residues are well separated and readily detected after 22 minutes. Recoveries of those residues from the vegetable oil samples wore bettor than 90% in the 0.02 to 0.08 ppm range. At the time this method was developed, samples of commercial oils including cottonseed, corn, safflower, soybean, peanut, and olive oils were analyzed for residues of those herbicides. No peaks were discerned in the chromatogram of any sample. Although the relative retention time of 2,4,5-trichlorophonol, a common formulation impurity and one of the metabolic decomposition products of 2,4,5-T was not reported, it should be less than that of pentachlorophenol, and thus amenable to detection by this scheme;. (9) Yip has also developed a paper chromatographic method which allows qualitative determination of the same esters (28). A workable separation of the methylated acids was obtained using 35% dimethyl formamide in ether as the immobile phase and 2.2,4-trimcthyl pentano as the mobile phase. The sensitivity of the paper chromatographic technique is 0.1 ppm. The procedure recommended by Yip (26) for analysis of residues on green crops involves high speed of blending finely chopped greens with a mixture of II2SO4, cthanol, petroleum ether and ethyl other. The solids arc removed by centrifugation and the liquid extracted with sodium bicarbonate and chloroform, as for samples of vegetable oils. The procedure for wheat involves first grinding the wheat kernels in a mill to pass a 30-mcsh screen. The ground wheat is then blended with 95% othanol at high speed. The solids are separated by centrifugation and the residues extracted from the supernatant liquid as above. 2. Bound Residue. The above methods are adequate for the analysis of 2,4,5-T residues that are in the form of the free acid or various esters. The detailed analytical method provides steps for the separate examination of the residues present in free acid and ester forms although the esters are rarely found as residues in crops. 18 �An issue of primary concern, however, is whether there can exist in crops residues of 2,4,5-T chemically bound such that they arc not extracted and detected by the standard analytical method. Crosby (4) showed that a water soluble, ether insoluble hydrolyzable form of 2,4-D is present in bean plants treated with 2,4-D. It has been reported that 2,4-D as well as other herbicides can bo converted to eocny/mc-A thiocsters (3); this is a possible form for the "bound" material. It has also been suggested that 2,4-D may be bound as 2,4-dichlorophonoxy acetylglucosidc (15). 2,4,5-T could presumably undergo analogous reactions to give the corresponding bound forms. The analytical method that has been used in most plant residue studies provides no information on the, fraction that may be present in bound form. In a study of 2,4-D residues in forage and milk, the residue levels shown in Tables 5 and 6 were found by the standard analytical method (16) (29). TABLK o.—Residue of 2,4-D in forage samples from pastures sprayed with butyl ester or 2-elhylhexyl ester of 2,4-D at a rale of 2 Ibs/acre. Average of 1 to 5 determinations. —After Klingman et af, (16) 2,4-D residues, ppm, from Date, Mt Butyl ester Acid 6" 6'' 8 10 13 .. - - - 2-cthylhexyl oster Butyl ester 0 68.3 19.2 «. 0 5.0 0 0.10 0.18 0.03 0 Ethyl ester 0 0.04 0.02 0.03 0 Ethylhcxyl ester Acid trace 36.6 38.6 23.8 13.7 0 11.8 6.7 2.0 1.4 • Sampled just before spraying. i> Sampled within >£ lir after spraying. Eesiduos detected by the standard method were largely in the form of the acid rather than the original esters. Some degradation of the but3destcr to the ethyl oster apparently occurred. Essentially no trace of residue was found in milk from dairy cows gra/ing in pastures sprayed with 2,4-D (Table 6). TABLE 6.—Residue of 2,4-D in milk, as determined by two methods of analysis, from dairy cows grazing in pastures sprayed with esters of 2,4-D at 2 Ib/A on morning of May 6, 1963. Samples taken from morning milkings only."—After Klinyman, el al(18). 2,4-D residues in milk, ppm from Date, May after butyl ester FDA 6 7 8 9 10 11 13 . i-O 1 2 3 4 5 7 0 0.01 .01 .01 .01 .01 .01 SWR1 0 0.01 .01 .01 .01 .01 .01 2-clhylhozyl ostor FDA 0 0.01 .01 .01 <. 01 .01 SWRI 0 0.03 .02 < 01 .01 .01 .01 « Cows were kept in pastures continuously, except during milking. All data wore rounded to nearest 0.01 because this is about the practical limit of precision of the methods used. FI)A=Food and Drug Administration and SWIU=Southwest Research Institute. i> Milk was sampled in the morning before pastures were sprayed. 19 �The presence of bound 2,4-D in the grass samples from the pasture sprayed with the ethylhoxyl ester of 2,4-D was also checked. To demonstrate; the presence of bound 2,4-D, the acid and ester were extracted from the forage samples as usual. The filtrates were then extracted throe times with ethyl ether to remove any residual 2,4-D acid and finally heated on a steam bath for 16 hours under highly acidic conditions. Presence of bound 2,4-D would be indicated if amounts of 2,4-D found in the hydrolyzatos were significantly higher than those found in the filtrates before hydrolysis. Results arc, shown in Table 7. TABLK 7.—Ppm of %,4-D in grass of ethylhexyl ester-sprayed pasture, free and bound. (29) Days after spraying Control 2 4 .. 7 Initial extraction 46 50 20 19 Filtrates before hydrolysis 0 063 0.430 0. 24f> 0. 230 Ilydrolyzate (i) (') 0.64 1.31 ' Trace. The presence of small amounts of bound 2,4-D is shown by the value obtained from the hydrolyzates. There is a trend toward increasing formation of bound 2,4-D with time. No bound residues could be detected in milk in these experiments. The results from these experiments suggest that although bound residues were detected, most of the residues were present as acid or ester and there would not have been a major discrepancy betAvcen the results of the standard method and the actual total residue concentration. There is evidence for the binding of residues of 2,4,5-TP (Silvex), the phonoxy propionic acid analog of 2,4,5-T. A careful study of 2,4,5-TP residues in orange peel, however, suggests that a rather high percentage of the growth regulator residues can be present as insoluble "bound" materials (10). 2,4,5-TP fractions could bo separated on the basis of solubility into four types: free acid, ester (hoxanc soluble), complexed acid (water soluble, hcxane insoluble), and heat-labile complexed acid (heat-released). It was possible to detect the water soluble complexed acid as the methyl ester after basic hydrolysis and identification. The labile form was released after heating for 24 hours at 104-105° C. The concentrations of these various forms during a 13-week period arc shown in Fig. 2. 20 �O—-FREE ACID A—SOL. CONJ. ACID •— HEAT LABILE A G I O 3 5 7 9 II WEEKS ELAPSED FIGURE 2.—After Hendrickson and Meaghor (10). Those results suggest that the original 2,4,5-TP aminc salt is first converted to the free acid. This acid then is converted to a soluble conjugated form. However, it appears that the insoluble complexcd form ultimately becomes a major fraction of the total residue. The results of this and other studies of herbicide residue in citrus (7), (18) emphasize that the residues of halogcnatod phcnoxyacetic acids may take several forms in plant tissues. Unless an effort is made to release the bound residues, the standard analytical scheme does not provide a suitable basis for estimating the total residue concentration.* CHEMICAL STABILITY OF 2,4,5-T 1. Photochemical Degradation. Ultraviolet light has been shown to alter drastically the structure of many pesticides under laboratory conditions. Knowledge of whether sunlight under "field conditions" can also affect these transformations is critical. The detailed chemistry and toxicology of the resulting decomposition products could bo significant to agriculture and the public health. Although the photochemistry of 2,4,5-T has not been investigated, considerable effort has been expended to elucidate the pathway for photochemical decomposition of 2,4-D. It might be expected that these compounds react in a similar way. Several studies indicate that *It is possible that only the pure acid and ester residues produce physiological effects oilman and animals, while the bound forms are inert and non-toxic. The standard analytical scheme would then provide a useful measure of the effective concentration of residue in toxic form. The relative physiological effects of bound and unbound residues arc unknown. 21 �2,4-D is, in fact, degraded in the presence of ultraviolet light to phenolic products (19), (1), (2). Some evidence is available which indicates that sunlight also detoxifies 2,4-D as Pcufound and Minyard (20) showed that malformations of water hyacinth and kidney bean plants were more severe in shaded plants than in those receiving full sun. The most recent photochemical study (5) is the first to compare the transformations induced by sunlight and ultraviolet light. Photolysis in the presence of sodium bicarbonate (2XHP 1 M) and water leads to several isolablc products: 2,4-dichlorophonol, 4-chlorocatcchol, 2-hydroxiy-4-chlorophcnoxiy-acctic acid, and the major product, polymeric humic acids.** Although the transient 1,2,4-bcnzonctriol could not initially be isolated, it could bo trapped if oxidation of this intermediate was inhibited by carrying out the photolysis in the presence of excess sodium bisulfite. These results suggest the following sequence: OH on \ \ OCHsCOOII on HI FIGURE 3 Proposed mechanism of 2,4-D photodccomposition After Crosby (4) Analogous results were obtained from irradiation in sunlight. 2. Hydrolysis. The esters of 2,4,5-T are readily hydrolyzed to the free acid under acidic or basic conditions. The esters are rarely found in residues in crops. The rates of hydrolysis of course depend on the detailed stereochemistry of the ester substituent. The rate; of hydrolysis is reduced as the bulk of the ester group is increased close to the oxygen linkage. **No attempt was made to determine the fate of the two carbon fragment. 22 �3. Thermal Stability. 2,4,5-T is stable with respect to thermal degradation to at least its melting point of 153° C. 4. Biochemical Degradation. 2,4,5-T is slowly degraded in soil which contains organic matter under warm, moist conditions. The generally accepted half-life for this process is several weeks. However, the decay in 2,4,5-T concentration is usually not a simple first order process since the population of organisms that metabolize 2,4,5-T increases in the presence of 2,4,5-T. In areas pro-treated with 2,4,5-T, the lifetime for degradation is significantly reduced. Three months appears to be the accepted length of time for 2,4,5-T residues in soils to disappear completely. The rate of disappearance appears to be independent of the quantity of application. Some, of the organisms responsible for 2,4,5-T biodegradation have been isolated and identified. (17) The subject of residues is more fully examined in Section VI. REFERENCES (1) (8) (S) (4) (5) (6) (7) (8) (9) (10) (11) (12) ALY, 0. M. and FAUST, S. D., J. Agrie. and Food Chcm. 12:54:1, 1964. BELL, G. R., Botari. Gas. 118:133, 1965. BOKCII, M. K., Plant Physiology. 30:558, 1961. CROSBY, D. G., J. Agric. and Food Chcrn. 18:2, 1964. CKOSBY, D. G., and TUTASS, II. O., J. Agric. and Food Chcm. 14:596, 1966. Dow Chemical Company, Personal communication. ERICKSON, L. C., BUANNAMEN, B. L., and COGGINS, C. W., J. Agric. and Food Chcm. 11:437, 1963. FRUAR, D. E. II., Chemistry of the Pesticides. 3rd. Ed., D. Van Nostrand Co., New York, 1955. GOVER-STRUL, G., KLEIGM, II. F. W., and MOSTAEUT, II. E. Analytica Chemica Acta 34:322, 1966. HENDKICKSON, R., and MEAGHEH, W. R., J. Agric. and Food Chem. 17:601, 1969. HIGGINBOTHAM, G. II., RESS, J., and FIRESTONE, D. Chemical and Engineering News 4^:53, 1966. HlGGINBOTHAM, G. R., HUANG, A., FlRESTONE, D., VERRETT, J., RESS, J., and CAMPBELL, A. D., Nature ##0:702, 1968. (IS) House, W. B., GOODSON, L. II., GADBERRY, II. M., and DOCKTEH, K. W., Assessment of ecological effects of extensive or repeated use of herbicides. Midwest Research Institute. Project No. 3103-B, December 1967. (14) KIMMIG, J., and SCIIULZ, K., Dermatologica 105:54:0, 1957. (15) KLAMIIT, II., Planta. 57:391, 1962. (16) KLINGMAN, D. L., GORDON, C. II., YIP, G., and BURCHFIELD, II. B., Weeds 14:164, 1966. (17) Loos, M. A. "Phcnoxyacotic Acids," KEARNEY, P. C., and KAUFMAN, D. D. (Ed.) Degradation of Herbicides. New York, Marcel Decker, Inc., 1965. (18) MEAGIIER, W. R., J. Agric. and Food Chem. 14:599, 1966. (19) PAYNE, M. G., and FULTS, J. L., Science 100:37, 1947. (80) PENFOUND, W. T., and MINYAHD, V., Botan. Gaz. 100:231, 1947. (81) TOMITA, M., VEDA, S., and NARISADA, M., > akugaka Zasshi, 79:186, 1959. U.S. Department of Agriculture, private communication. 23 �(S3) U.S. Department of HEW, FDA, personal communication. (24) U.S. Tariff Commission, "Synthetic Organic Chemicals. U.S. Production and Sales, 1967." Publication No. 295. (86) WOOTON, J. C. Chein. and Eng. News, 45:10, 1967. (26) YIP, G. J. Assoc. of Official Agricultural Chemists, 4S-.367, 1962. (87) YIP, G. J. Assoc. of Official Agricultural Chemists, 47:116, 1964. (28) YIP, G. J. Assoc. of Official Agricultural Chemists, 47:343, 1964. (89) YIP, G., and HEY, II. E., Jr., Weeds ^4:167, 1966. 24 �USES AND SIGNIFICANCE Summary 2,4,5-T has become important in land and waterway management. It has boon very useful for brush and wood eontrol. A result has boon a growing dependence upon it. The Government itself has encouraged the use of 2,4,5-T through an agricultural cost sharing program. Nearly 8 million acres were treated with 2,4,5-T in the United States in 1964. The major use was brush control on rangelands, pastures, and rights-of-way. Othor uses were on certain food and non-food crops, in aquatic wood control and in forestry. In 1964 arid 1966 almost half of the 2,4,5-T was used on rightsof-way. Over two million acres of rights-of-way were treated in 1964 which is one quarter of the total area treated with this herbicide. Civilian uses of 2,4,5-T dropped nearly 50% from, 1964 to 1966. More recent, unpublished information from the Department of Agriculture suggests that this trend continued through 1968 but may have begun to reverse itself within the past year. This decrease accompanied prico increases and shortages of supply associated with the demand for 2,4,5-T as a defoliant and tactical weapon in Vietnam. If acreage decreased proportionately, about four million acres would have been treated in 1966. To some extent, other herbicides can bo substituted for 2,4,5-T (notably 2,4-D). If all alternative herbicides wore available the banning of 2,4,5-T would appear to load to an additional cost of nearly $52 million in land and waterway management or nearly a 100% increase over the current expenditures. Those figures assume practices designed to achieve the current level of management and agricultural production. If other phcnoxy herbicides arc also banned, the additional costs from elimination of 2,4,5-T alone would amount to $172 million or over three times the present investment. Agricultural costs arc estimated to rise $32 million and $44 million, respectively, under the two assumptions, while costs of right-of-way management would rise $12 million and $75 million, respectively. Agricultural production has become dependent upon the use of herbicides. Their use in the United States has increased rapidly during the past few years. They are employed as substitutes for the more costly practices of hoeing, cultivating, mowing, chopping, burning, and various other cultural practices for the control of weeds. 25 420-165 O - 71 - 5 �One of the principal uses of tho herbicide, 2,4,5-T, is for control of woods and brush on pasture and rangoland. Largo quantities arc also used to control brush along roadways and under poworlinos. The principal crop use of 2,4,5-T is on hay and pasture. In forest production, 2,4,5-T has proved useful for selective wood control. 2,4,5-T acts upon deciduous hardwoods leaving the conifers with little injury. This treatment has been helpful in releasing conifers from deciduous hardwood competition in mixed stands. Production Total herbicide production in tho United States has increased rapidly: *1960 75,000,000 pounds (3) 1965 220,000,000 pounds (8) 1968 403,000,000 pounds (12} For 2,4,5-T (acid, esters and salts), production has increased as follows: 1960 1965 1966 1967 1968 7,900,000 pounds (7) 13,500,000 pounds (10) 18,100,000 pounds (10) 27,200,000 pounds (10) 42,500,000 pounds (18) A portion of this production is exported and a portion shipped abroad for military use. Uses 1. Domestic. a. Farm use. In 1964, of tho estimated 13,000,000 pounds of 2,4,5-T produced in the United States, only 13 percent or about 1,655,000 pounds wore used in agriculture (Table 1). About 40 percent of tho quantity employed in agriculture was used for weed control along fence rows, ditch banks, farm roadways, and other non-crop uses. Tho remaining 60 percent or 979,000 pounds was employed on crops (including hay, pasture and rangoland). Since 1964, tho use on farms has been decreasing. In 1966, 760,000 pounds were applied which is loss than 50% of the 1964 amount (IS). Use on hay, pasture, and rangoland declined 35 percent, and other crop use decreased by 31 percent, whereas non-crop use decreased about 84 percent. b. Forestry, Rights-of^way, Aquatic Weeds and Lawn and Turf. In 1964, about 888,000 pounds of 2,4,5-T wore used in private nonfarm forest management for control of undesirable trees and brush (Table 1); in 1966, this declined to 408,000 pounds (Table 3). An estimated 4,368,000 pounds wore applied to rights-of-way, roadways, fire lanes, and similar areas for tree and brush control in •Changes in the method of reporting after I960 make this figure difficult to compare with later figures. 26 �1964 (Table 1); in 1966, this had decreased to 2,315,000 pounds (TabloS). About 162,000 pounds were applied to aquatic habitats in 1964 for weed control on about 81,000 acres (Table 1); in 1966, this had dropped to 75,000 pounds (Table 3). TABLE I—Estimated use of 2,4,5-T in the United Stales, 1064 (1$) Quantities of Proportion of Land treated active total quantity per 1,000 acres 2,4,5-T applied applied per 1,000 pounds (Percent) Use category Farm use:1 Hay, pasture, and rangeland Other farm use -- 7 12 1 655 19 G56 600 4,368 888 162 583 7 7 49 10 2 6 4,488 .- 7, 257 81 7,939 Total non-farm use All uses-. 581 1 074 296 1 200 2 175 430 81 306 Total farm use Non-farm use: Federal Government agencies 3 Lawn and turf s treatment * Rights-of-ways Private non-farm forests a Aquatic treatment 7 _ Other uses 8 2 441 1 010 3 451 2 « 8, 912 100 1 Based on "Quantities of Pesticides Used by Farmers in 1964," AER 131. Farm data excludes Alaska and Hawaii. In some farm uses, all acres in a Held were reported treated while only spots actually received 2,4,5-T, thus making the rate per acre seem low. a Sum of the acres of all crops, except hay, pasture, and rangeland treated, plus an acreage estimate for noncropland receiving treatment. The acreage of noncropland was estimated by allocating the quantity of 32,4,5-T used for such purposes at the rate of 2 pounds per acre. Based on 1969 usage of the Departments of Agriculture, Interior, and Defense; and 1951-69 average usage by the Tennessee Valley Authority. 1 Based on estimated 500,000 acres of turf and 700,000 acres of lawns treated. Estimates based on "Extent and Cost of Weed Control with Herbicides and an Evaluation of Important Weeds," ARS 34-102; and un published data. ' Based on sources cited in footnote 4 with rate of application same as for federally treated rights-of-way. Docs not include rights-of-way treated by Federal agencies. « Estimated at 4 times the acreage treated and quantities of pesticides applied to public forests. ' Based on sources cited in footnote 4 and rates used on federally treated waterways. s Includes governments other than federal and any other usage. « Based on table 28 of the Pesticide Review 1969, Ag. Cons. Stab. Service. TABLE 2.—Farm use of ®,4,5-T on crops, by category of use, United States, 1964 and 1966 (IS) l Active ingredients per 1,000 pounds Use category 1964 2 19663 Hay, pasture, and rangeland Corn Wheat Rice Other crops - --"" 581 72 16 5 (') 264 41 979 Acres treated per 1,000 acres Percentage of planted acres treated with 2,4,5-T (percent) 1964z 19663 1964 < 1966 ' 379 2,441 255 58 26 55 fi 48 23 (') 196 34 117 127 861 337 59 18 16 99 175 0.4 0.4 (") 0.3 0.4 0.1 0.1 0.5 0.1 0.1 0.8 0.2 0.2 3, 112 1,,565 0.3 0.2 653 (0 1 Does not include Alaska and Hawaii. Use in 1964 generally reflects current practices. Use in 1966 was unusually small and not representative of current practices because of domestic shortages due to increased military purchases. 2 Revised estimates based on Quantities of Pesticides Used by Farmers in 1964. U.S. Dopt. Agr., Agr. Econ. Bpt. No. 131, Jan. 1968. 3 Data from the ERS Pesticide and General Farm Survey, 1966. * Acres treated as a percent of acres grown as reported in Stat. Bui. 384 and Agricultural Statistics 1968. s Acres treated as a percent of acres grown as reported in Crop Production, 1967. U.S. Dcpt. Agr., Cr. Pr. 2-2(7-67). ' Less than one-tenth percent. ' Included in other grains in 1964 only. 27 �TABLE 3.—Quantities of S,4,S-T used and percentage change in use, United States, 1064 and 1966 (13) Quantities of active 2,4,6-T applied per 1,000 pounds Use category 1964 i Farm use: 1 Hay pasture, and rangcland Other farm use .... 1966 2 Reduction from 1964 usage in percent Nonfarm use: Federal U overninent agencies _ _ Private nonfarm forests Aquatic treatment Other uses . All uses 8 2 379 2381 35 66 1,055 2 760 54 »450 ^300 « 2, 315 «408 "292 31 60 47 54 46 50 7 257 Total farm use 581 3,840 48 8,912 > 4, 600 48 1, 074 . - - 666 600 4,368 888 162 583 '76 1 See table 1. Data from 1966 ERS Pesticide and General Farm Survey, U.S. Dept. of Agrie. Based on decreases in Forest Service spending on timber improvement, and cooperative programs with states. 1 Assuming 50 percent shift to dicamba. • Residual after providing for other requirements. * Based on same rate of reduction as total farm use. ' Based on same rate of reduction in 2,4,6-T use on hay, pasture, and rangeland. ' Assuming 60 percent of the 1964 use of 2,4,6-T was retained. ' Based on tables 2 and 3. 2 3 About 600,000 pounds of 2,4,5-T wore applied to lawns and turf in 1964 (Tablo 1); in 1966 this had fallen to 300,000 pounds (Table 3). c. Fruit. Small quantities (loss than 10,000 pounds) of 2,4,5-T were used as a growth regulator to thin fruit in the spring and hold it on the tree until harvest in the fall (9)'. d. Federal Agencies. The DOD, USDI, and USDA are the chief Federal agencies that use 2,4,5-T on the lands they manage. During 1964 in continental United States the Federal agencies used a total 656,000 pounds (Table 1). In 1969 the DOD treated 162,000 acres with 221,000 pounds of 2,4,5-T in continental United States (16). The majority of that used by the Department of Defense was by the U.S. Army Corps of Engineers Civil Works Program for the control of aquatic weeds in navigable waters, in and around reservoirs, on stream banks and rights-of-way. The use of horibcides on DOD installations is generally restricted to small areas such as training sites, lawns, fringes of air fields, fence rows and ammunition storage areas. During 1969, the USDI treated 52,900 acres of rangeland with 38,200 pounds of 2,4,5-T; in addition 2,200 acres of aquatic habitats were treated with 5,600 pounds (17). In 1969, the USDA treated 107,000 acres of timberland with 221,000 pounds of 2,4,5-T. In addition, 34,000 acres of rangeland and 28 �2,000 acres of rights-of-way were treated with 94,000 pounds (unpublished figures). c. Economic Importance. It is estimated that herbicides contribute significantly to the profits of agriculture. For example, if phcnoxy herbicides (including 2,4,5-T) were not available, the not loss to rice producers in the United States has been estimated at $7.6 million per year. This represents some 2% of the farm value, of all of tho rice produced in the United States per year or about 25% of the value of production from acres treated with phonoxy herbicides (13). 2,4,5-T has a major use for control of brush under transmission lines. It is estimated (13) that tho control of brush with 2,4,5-T on rights-of-way costs about $6.50/acre. Other chemicals which could bo substituted for 2,4,5-T on most of this acreage would cost $42/acrc. Manual control costs about $44/acre. Tho loss to agriculture if 2,4,5-T were no longer available would bo about $32 million (based on normal use in 1964 (see Table 4)). Because of military demands for 2,4,5-T in Vietnam, the quantity used in agriculture has declined by about one-half (Table 3). It has boon estimated that the increased costs of alternatives for 2,4,5-T for nonfarm use were about $20 million for 1964 (Table 4). Between 1964 and 1966 these uses wore also cut in half (Table 3). If 2,4,5-T were not available and other phenoxy herbicides could not bo used as alternatives, it is estimated that tho domestic cost would be approximately $172 million (about $44 million for farm use and $128 million for nonfarrn use (Table 5). f. Registered Uses. The registered uses of 2,4,5-T are shown in Table 6 for food-crop use and in Table 7 for non-food crop use (14)- 29 �TABLK 4.—Economic effects of banning %,4,8-T, if other phenoxy herbicides and all other registered herbicides could have been used, United Stales, 1970 (13) Use category Farm use: II ay , pasture, rangeland 3 Acres Acres requirEstiing that mated could bo addiacres treated tional treated with cultural with alternaprac2,4,5-T i tive tices 1,000 acres 1,000 acres 1,000 acres Cost of 2,4,5-T and application 1,000 dollars Cost of alternative herbicides Cost of additional and cultural applipraccation tices 1,000 dollars 1,000 dollars Net increased cost of using alternative 1,000 dollars 2,441 1,010 488 879 1,953 774 4,062 3 968 1,781 3,245 32, 443 2 486 30, 172 1,763 3,451 1,367 2 727 8,020 5,026 34,929 31, 935 281 3,287 2,850 33, 772 3,738 3,765 3,720 36,028 4,411 735 240 387 72 291 16 60 217 43 8 15 9, 548 3,363 2,219 3,026 240 375 1.213 1.110 11, 804 4,036 Nonfarm use: Federal Government 5 Lawn and turf 8" , . Uights-of-way 7 Private nonfarm forests 7 B Aquatic areas 7 lo Other » 1,200 2,175 Total nonf arm use 4,488 4,190 358 46,474 51,710 14,601 19, 737 Total all uses 7,939 5,557 3,085 54,494 66, 736 49,430 51, 672 290 430 81 300 1,200 1,958 608 760 392 1,182 1 From Table 1. 2 Cost of alternative herbicides and application plus cost of additional cultural practices less cost of 2,4,5T and application. ' The alternative herbicide was 0.5 Ibs. silvex and 1 Ib. 2,4-D on 20% of the acres treated. Cultural treatments on the other 1,953,000 acres include renovating a third of the acres at $16.66 an acre; then bulldozing 72% of the remaining two-thirds at $23.16 an acre, and mowing the other 28% at $1.50 an acre. 4 Most acres of individual crops treated with 2,4,5-T in 1964 could have been treated with 2,4-D. Silvex was applied with 2,4-D on the noncroplarid. Bates of 2,4-D use on crops wore assumed to bo the 1966 average rate of all phenoxy usage for that crop except for other grains where 2,4-D was used at the same rate as 2,4,5-T. Supplemental hand or mechanical control was used on some of the corn, sorghum, and noncropland. Additional acres of wheat, other small grains, and other crops wore grown to maintain production in spite of yield \osses. In rice production, additional fertilizer and a change in the crop rotation were required to maintain production and offset loss in quality. ' Based on 1969 use by the Departments of Agriculture, Interior, and Defense; and TVA. Two Ibs. each of 2,4-D and silvex were substituted lor 2,4,5-T on 95% of all acres treated in 1964. Remaining acres required additional cultural, mechanical, and manual controls averaging $49.00 per treated acre. • All acres could have been treated with 0.5 Ibs. each of 2,4-D and silvox, but $4.00 of manual work was also required on 6% of all acres. 7 Two Ibs. each of 2,4-D and silvex were used as substitutes for 2,4,5-T on 90% of all acres. 8 Ten percent of the acres required hand cutting at $44.00 per acre. 'Ton percent of the acres were mowed, hand cut, or undesirable species girdled at a cost of $78.21 per acre. "The remainder required cleaning with a drag line at $30.00 per acre for treated acres. 11 Two pounds each of 2,4-D and silvex wore used to replace 2,4,5-T on 95% of those acres. The remaining acres required mechanical control by hand or with machines at $26.00 per acre on which used. 30 �TABLE 5.—Economic effects of banning 2,4,6-T if no other phenoxij herbicides could have been used but all other registered herbicides could have been used, United Slates, 1070 (13) Acres Acres requirEstithat ing mated could be addiacres treated tional treated with cultural with alternaprac2,4,5-T i tive tices Use category Farm use: Hay, pasture, and rangcland '. .Other farm use 4 Total all uses 1,000 acres 1,000 dollars 1,000 dollars 1,000 acres 1,000 acres 1,000 dollars Not increased costiof using alternative 3 1,000 dollars 628 2,441 618 4,052 3,908 6,386 40, 551 5,167 36,490 7, 685 028 3,059 8,020 0,386 45,718 44,084 296 1,200 2,175 430 81 300 .. 2,441 1,010 3 451 Total farm use Noiifarm use: Federal Government 5 fl Lawn and turf ? Rights-of-way Private nonfarm forests 8 Aquatic areas ° - -_ O thcr 10 Total nonfarm use Cost of 2,4,5-T and application Cost of alternative Cost of addiherbicides tional and cultural pracapplication tices 83 1,200 1,631 213 1,200 544 430 .81 306 3,287 2, 850 33, 772 3,738 008 2, 219 . 3,901 2,310 84, 812 10, 803 4,800 23,936 33,030 2,430 7,650 11,477 4,260 74,976 20,892 1,822 5,431 4,488 2,914 2,774 46,474 91,023 83, 309 127,858 7, 939 3,542 5,833 54,404 97,409 120,027 171, 942 1 2 From Table 1. Cost of alternative herbicides and application plus cost of other treatments less cost of 2,4,6-T and application. 3 Cultural treatments include renovating a third of the acres at $15.66 an acre; then bulldozing 72% of the remaining two-thirds at $23.16 an acre, and mowing the other 28% at $1.50 an acre. 1 Weeds on some acres of most crops treated with 2,4,5-T in 1964 could have been controlled with nonpliouoxy herbicides. Important chemical substitutes used include dicamba, atrazinc and oil on crops and picloram on noncropland. Supplemental hand or mechanical control was also required on some corn, sorghum, small grains, and noncropland. Additional acres of wheat, other small grains, and other crops were grown to maintain production in spite of yield losses. In rice production additional fertilizer arid a change in the crop rotation were required to maintain production and offset loss in quality. 5 Based on 1969 used by the Departments of Agriculture, Interior, and Defense; and TVA. Two pounds of picloram with a drift reducing adjuvant were substituted for 2,4,6-T on 75 percent of federally maintained rights-of-way. All other acres required cultural, mechanical, and manual control averaging $51.00 per acre. «All acres can be treated with 0.5 pound dicamba but supplemental manual work costing $4.00 per aero was required on all acres. ' Two pounds of picloram with a drift reducing adjuvant were substituted for 2,4,5-T on 75 percent of all acres. The remainder required hand cutting at $44.00 an acre. 8 All acres had to bo mowed, hand cut, or undesirable species hand girdled at a cost of $78.21 per treated acre. 1 All acres needed to be mechanically cleaned with a drag lino at $30.00 per aero treated. 1(1 All acres required mechanical control by hand or with machines at $25.00 per acre. 31 �USDA Summary of Registered Agricultural Pesticide Chemical Uses 2,4,5-Trichlorophenoxy acetic Acid (Principal formulations: EC esters; amine salts; Type pesticide: Herbicide and plant regulator) Use Tolerance (ppm) Dosage Limitations Ib. actual/A. _ _. Heavy brush. Apply when in full leaf and after grass is well established. 1 Light brush. Apply when leaves arc fully expanded. Rangeland clearance Extended-. 4 _. Apply in spring by airplane when brush is in heavy foliage stage (40-90 days after leaves unfold). Apples (Mclntosh) Extended... 20ppmspray Prcharvest drop control. Apply a single ap(acld cquivaplication 4-5 days before drop normally lent). begins. Blueberries (low bush).. Extended.-. 1.0 (acid Spray on revolving cloth-covered drum held equivalent). above blueberry foliage. Apply during Juno and July of season preceding a burn. Do not apply within 2 years of harvesting berries. Grains, cereal Extended-.. 0.5.._ Apply when grain is in tiller to boot stage and (undcslgnated). weeds arc In actively growing condition. Do not apply from boot to milk stage or in seedling stage. Pastures: Grasses Extended... 3 Heavy brush. Apply when in full loaf and after grass is well established. 1 Light brush. Apply when leaves arc fully expanded. Hangeland clearance Extended-.. 4 Apply in spring by airplane- when brush is in heavy foliage stage (40-90 days after leaves unfold). Rice Extended.-- 1.25 Apply tiller to boot and before flooding (4-8 weeks after rice emerges). 1.6 -— Apply after flooding (2-3 weeks) or 7-10 weeks after planting. Sugarcane Extended... 1 Preemergenco use only. (Louisiana). If cane is shaved and oft-barred, treat Immediately following this operation. 4.6 Proomergencc use only. (Hawaii). Apply just before cane emerges. 1 Postemergenco (weeds in established cane). Apply over row when weeds are growing vigorously. Do not apply after cane Is 2 feet tall. Lakes; Ponds Extended... 4 (with 201bs./A. Broadcast application in early spring to sum2,4-D as ester). mor. Do not use treated water for crop irrigation or livestock drinking water. Pastures: Grasses Extended... 3 TABLE 7.—The nonfood crop uses of 2,4,5-T. The doses listed below are given in pounds of 2,4,6-T and equivalent in 100 gallons of spray using water or oil as the vehicle. (USDA, Pesticide Regulation Division, as amended by Pesticide Regulation Division Notices 70-11 (4/20/70) and 70-18 (6/1/70). Non-food crop uses Around farm buildings and yards Farm fence rows, lanes and roads Pino release In hardw90d forest Industrial buildings including: Around factories, elevators loading platforms, oil refineries, etc. Industrial sites: Airline beacon stations, airport runways, coalyards, electric transformer stations, lumberyards, parking areas, radio towers, railroad sidings, sawmills. Recreational areas Including: Race tracks, wildlife management Rights-of-way: Fire lanes, highways, pipelines, powerlines, railroads, telephono and telegraph. Vacant lots Pounds 2,4,5-T acid Comment 2 2-6 2-6 12-16 3-12 5.6-10 4-20 2-4 2. Military Uses of 2,4,5-T. The phrase, military uses, refers to the employment of 2,4,5-T as a defoliant in operations. Basic research on herbicides proceeded through the period 1941-1947. The work was encouraged by efforts 32 �to develop defoliating agents for use in jungle areas of the South Pacific area during World War II (2). A major demonstration of the utility of the mixture now known as Orange (1:1 mixture of the butyl esters of 2,4-D and 2,4,5-T) as a defoliant for military purposes was conducted in 1959 (1). A preliminary series of defoliation trials was conducted in Vietnam between July 1961 and April 1962 (3). Operational spraying began in Vietnam in 1962 and increased sharply after 1967. Reviews on this subject are available (3, n, 6). Two herbicide formulations used in military operations in Southeast Asia include 2,4,5-T: Agent Composition rurplo. Lb./Oal. of active material n-L>utyl ester 2,4-D 50% (wt.)_ n-butyl ester 2,4,5-T 30% (wt.). Isobutyl ester 2,4,5-T 20% (wt.). n-butyl ester 2,4-D 60% (wt.) n-butyl ester 2,4,5-T 50% (wt.). Orange 8.9 8.!) Purple mixture was discarded early because it was found to be no more effective than Orange,. Orange; is applied at a rate of 24 Ib. per acre from both fixed wing aircraft and helicopters. C-123 aircraft fly at 150 feet altitude at 130 knots. A swath of 240 feet per pass is sprayed. Typically, a formation of 3-9 aircraft fly at the same time. The following table shows the total areas sprayed each year between 1962 and 1968. TABLE 8.—Land area in Vietnam to which defoliants have been applied between 1962 and 1968 (IB) Year 1962 1963 1964 1965 1966 1967 1968 Number of acres sprayed 4,940 24,700 83,486 155,610 741,247 1,486,446 1,267,110 It has been estimated that under usual operating conditions 90% of the released material is confined to a band about 2.0 km wide on cither side of the 80 motor spray path (15). This figure is based on the spectrum of particle sizes, the direction and speed of the crosswind, and the altitude. Under realistic conditions but with a crosswind at right angles to the flight path, only 0.1% of the spray would be deposited between 1 and 2 km from the center lino of the flight path. As shown in Table 8, the total area sprayed for defoliation in 1968 was less than in 1967. Defoliation was discontinued in April 1970. 33 �Defoliation operations have been carried out to some extent in virtually all sections of South Vietnam. The major use has been within War Zone C, War Zone D, and the Kung Sat Special Zone. These three areas comprise about one-fifth of the total area to which defoliants have boon applied. The Kung Sat Special Zone is an area which surrounds the shipping channel into Saigon. 113,600 acres had been sprayed by the end of January 1968 (6). War Zone C is northwest of Saigon between the Song Bo Kiver and the Cambodian border. 227,000 acres had been treated in War Zone C by January 1968. War Zone D, in which 405,000 acres were treated, is northeast of Saigon between the Song Be and Song Dong Ilai Rivers (#). Repeated application was made in some areas. The general purposes for which defoliation operations have been used include: a. Defoliation of lines of communication. Sites of frequent ambush have been defoliated to afford better visibility along roads and trails. b. Defoliation of areas whore Viotcong tax collectors customarily exacted payments from the populace. c. Defoliation of enemy infiltration routes. d. Defoliation of enemy base camps. The rationale in this case was based on the observation that the enemy tended to move out of a base after the area had been sprayed. e. Clearing of vegetation around American base camps and fire bases in order to clear fields of fire and improve observation. Importance of 2,4,5-T as a military defoliating agent. Systematic studies have not boon carried out to quantify the value of defoliation in Vietnam. However, many of those concerned with the program believe that the military advantages are clearly evident (4, 15). The following evaluations arc extracted from testimony offered by Rear Admiral W. E. Lemos before the Subcommittee on National Security Policy arid Scientific Developments of the Committee on Foreign Affairs (4). a. Major defoliation has been accomplished in War Zone C. Prior to defoliation, 7 brigades were necessary to maintain US/GVN presence. After defoliation, only 3 brigades were required. b. The Commander of Naval Forces in Vietnam in a report to General Abrams stated: "As you know, a major concern is the vegetation along the main shipping channel. Your continuing efforts under difficult and hazardous flying condition, in keeping this area and the adjacent inland areas devoid of vegetation have contributed considerably in denying the protective cover from which to ambush the slowmoving merchant ships and U.S. Navy craft." c. In 1968, the Commanding General of the First Field Force reported: "Defoliation has been effective in enhancing the success of 34 �allied combat operations. Herbicide operations using C-123 aircraft, helicopters, truck mounted and hand sprayers have become an integral part of the II CTZ operations against VC/NVA. The operations arc normally limited to areas under VC/NVA control remote from population centers. The defoliation program has resulted in the reduction of enemy concealment and permitted increased use of supply routes by friendly units. Aerial surveillance of enemy areas has improved and less security forces are required to control areas of responsibility. An overall result of the herbicide program has been to increase friendly security and to assist in returning civilians to GVN control." d. The U.S. Commander in the III CTZ related: "Herbicide operations have contributed significantly to allied combat operations in the III Corps. Defoliation is an important adjunct to target acquisition. Aerial photographs can often be taken from which interpreters can "see the ground" in areas that previously were obscured. Defoliation also aids visual reconnaissance. USAF FAC's (forward air controllers) and U.S. Army aerial observers have discovered entire VC base camps in defoliated areas that had previously been overlooked." e. In the south in the IV CTZ, C-123 herbicide operations are limited. This is because of the vast areas of valuable crops which are not to be destroyed, even though they may be in enemy hands. Therefore, commander of the IV Corps area in presenting his evaluation cited the value of helicopter operations as follows: "A significant helicopter defoliation mission was conducted in the vicinity of SADEC in August 1968. The target area consisted of 3 main canals which converged and formed a strong VC base. The dense vegetation permitted visibility of only 10-15 meters horizontally and nil vertically. The area was sprayed with approximately 135 gallons of herbicide White and over 90 percent of the area was defoliated. As the result of the defoliation, an ARVIN battalion was able to remain overnight in the area for the first time in five years. Many enemy bunkers were open to observation. Since the defoliation, the VC presence has decreased to the point that only RF/PF forces are now necessary foi local security." f. As a part of the 1968 evaluation report of herbicide operations, the U.S. Senior Advisor in the IV Corps Tactical Zone area reported: "A section of National Highway 4 in Phong Dinh Province was the site for a defoliation operation on 24 June 1968. Since January 1968, a series of ambushes was conducted against SYN convoys and troop movements. Because of the total inability of ground troops to keep the area clear of VC, this area was sprayed using 685 gallons of herbicide White1,. The target area was primarily coconut palm and banana trees that had been abandoned by their owners for several years. During the period of abandonment the vegetation had become so dense that convoy security elements were not able to see more then five meters into the underbrush and had to rely on reconnaissance by 35 �fire to discover the hidden enemy. This method of protection had proven ineffective. Three RF/PF companies with U.S. advisors were used to secure the target for the helicopter operation in addition to an armored cavalry troop. Since the defoliation mission was completed, convoys have used the highway 2 or 3 times a week without attack or harassment. Only one IIF platoon has remained in the area to provide local security to the hamlet and highway." g. In certain instances, we know the VC have been forced to divert tactical units from combat missions to food-procurement operations and food transportation tasks, attesting to the effectiveness of the crop destruction program. In local areas where extensive crop destruction missions were conducted, VC/NVA defections to GVN increased as a result of low morale resulting principally from food shortages. The most highly valued item of equipment to field commanders in Vietnam is the helicopter. There was some question when the helicopter spray equipment was first procured whether field commanders would divert the use of helicopters from combat operations for herbicide spray operations. The very fact that the commanders have used their helicopter spray equipment to the fullest and have asked for more is certainly proof that herbicide operations have been helpful in protecting the American Soldier and contributing to successful accomplishment of the ground combat mission." (4) Cost Sharing Programs The Agricultural Stabilization and Conservation Service of the U.S. Department of Agriculture has provided a cost sharing program for farmers in order to encourage desirable farm and conservation practices. Included in this Agricultural Conservation Program are two programs in which 2,4,5-T was used: 1. Control of competitive shrubs on range and pastures. In 1968, $7 million were paid to farmers who treated 1.9 million acres. Approximately one-half of this land was treated with chemicals, a substantial part of which was 2,4,5-T. The remainder was treated by mechanical means. 2. Control of specified noxious weeds on farmland or biennial weeds on pasture and range lands. In 1968, $1.75 million wore paid to farmers to treat 700,000 acres. In some cases 2,4,5-T was used, although in most cases, 2,4-D and other chemicals were employed. REFERENCES (1) BROWN, J. W. Vegetation Control, Camp Drum. U.S. Army Biological Laboratories, Crops Division, Frederick, Md. Summary lloport, 1959. (2) DHLMORE, F. J. Importance of defoliation in counter emergency operations. Proc. First Defoliation Conference, July 29-30, 1963. 36 �(5) HOUSE, W. B., GOODSON, L. II. GADBBERY, II. M., and DOCKTEK, K. W. Assessment of ecological effects of extensive or repeated use of herbicides. Midwest Research Institute, Proj. No. 3103-B, December 1967. (4) LEMOS, W. K. Testimony before the Subcommittee on National Security Policy and Scientific Development. Committee on Foreign Affairs, House of Representatives, December 15, 1969. (6) PETERSON, G. E. The discovery and development of 2,4-D. Agricultural History, Vol. XIL(3), 11243-259, U.S. Government Printing (Mice, 1967. (6) TSCIJIMLEY, F. II. Science 163:779, 1967. (7) U.S. Department of Agriculture. The Pesticide Situation for 1962-1963. USDA, Agricultural Stabilization and Conservation Service. (8) U.S. Department of Agriculture. The Pesticide Review 1966. USDA, Agricultural Stabilization and Conservation Service. (9) U.S. Department of Agriculture. Quantities of Pesticides Used by Farmers in 1964. USDA, Economic Research Service. Agricultural Economic Report No. 131, 1968 (10) U.S. Department of Agriculture. The Pesticide, Review 1968. USDA, Agricultural Stabilization and Conservation Service. (11) U.S. Department of Agriculture. Quantities of Pesticides Used by Farmers in 1966. USDA, Economic Research Service Agricultural Economic Report, 1969. (1H) U.S. Department of Agriculture. The Pesticide Review 1969. USDA, Agricultural Stabilization and Conservation Service. (IS) U.S. Department of Agriculture. Report and tables on domestic use of 2,4,5-T, 1964 and 1966, supplied by Production Resources Branch, Farm Production Economics Division, July 1970. (14) U.S. Department of Agriculture. Information and tables on registered uses of 2,4,5-T, supplied by Pesticides Regulation Division, Agricultural Research Service. (15) U.S. Department of Defense. Material supplied by Department of Defense Research and Engineering, November 1969. (16) U.S. Department of Defense. Unpublished report. (17) U.S. Department of the Interior. Table on herbicide use by USDI. Supplied by U.S. Department of the Interior, 1969. 37 �TOXICOLOGY Summary Relatively little toxicological information has been available on 2,4,5-T. Most of the experiments prior to the National Cancer Institute screening study wore of acute, single-dose or short-term toxicity. The longest period of observation was 90 days. It was assumed (not unreasonably) that the several phenoxy herbicides behaved in similar fashion toxicologically. Hence, an understanding of aspects of the toxicology of 2,4,5-T was inferred from experiments with 2,4-D. The sample sizes used in many of the early toxicity studios wore so small that it is difficult to draw statistically valid inferences. The studios indicated that 2,4,5-T is only moderately toxic. Relatively little is known about the mechanisms of toxicity of 2,4,5-T or of its metabolism in man and animals. The screening study of pesticides carried out under contract for the National Cancer Institute tested the tcratogonicity of a number of compounds, including 2,4,5-T. 2,4,5-T appeared to bo tcratogcnic in mice and rats. Subsequent studies have confirmed these observations and in addition indicated that purified 2,4,5-T containing loss than 1 ppm of the toxic contaminant tetrachlorodiboiiz-p-dioxin as well as 2,4,5-T contaminated with 27 ppm dioxin are tcratogcnic. It has also boon reported that dioxin by itself is toratogenic. Tumor production by 2,4,5-T was not found. Accounts of birth defects in defoliated areas of Vietnam have been reported. The information available docs not permit the conclusion that 2,4,5-T used in Vietnam has been the cause of human birth defects. 2,4,5-T is classed as a plant hormone since, in appropriate amounts, it accelerates plant growth. The mechanism of the herbicidal effect is not fully understood. However, it is generally believed that excess growth stimulation and herbicidal properties arc related. Horbicidal effects occur when those materials arc used in largo doses. 38 �A. Acute Toxicological Investigations Toxicologioal studios on 2,4-D wore first reported in 1944 (8). However, there were no published reports of toxieologlcal investigations of 2,4,5-T until 1953. In that year, Drill and Hiratzka (5) reported a series of studies of acute; arid subacuto toxicity of 2,4,5-T on dogs. The material used was commercially available 2,4,5-T (presumably the acid) and was administered in capsules mixed in dog food. The single acute dose ranged from 50-400 mg/kg/. Chronic toxicity was studied in this case by oral administration in doses of 2-20 mg/kg/day, 5 days per week over a period of 13 weeks. Observations and measurements made; included determination of the number of days until death ensued, changes in body weight, general observations of abnormal physical signs, gross pathology of organs, and selected histology. The number of animals used was small (as few as one, per dose and as many as four per dose). In brief, the findings of this study suggested that a single, fatal dose for dogs lay somewhere between 100 and 400 mg/kg. It was inferred by the author that the acute, LD50* was around 100 mg/kg for dogs. Repeated daily doses of 20 mg/kg led to the death of all four animals tested within 11-75 days. Repeated daily doses of 10 mg/kg did not prove fatal over a 90-day period. There, wore some overt signs of toxicity including weight loss, stiffness of hind legs, muscular weakness and, occasionally, bleeding from gums. The Dow Chemical Company, a manufacturer of 2,4,5-T, undertook a scries of studies of acute toxicity of this material beginning around 1950. This series included a variety of species of animals and a number of the various salts and esters of 2,4,5-T and several of the various formulations. The details of these studies have never been published in the open literature. A number of them have been submitted as background material for a petition for the granting of a tolerance for the herbicide for uses of food crops. In 1954, a summary of some of this work was published by Rowe and Ilymas (17). Table 1 lists the various horbicidal agents tested. *LDto median lethal dosc=thc amount of a toxic agent which will be lethal to 60% of the test animals to which it is administered under tho conditions of the experiment. 39 �Table 1. Hcrbicidal formulations. TABLE 1.—Ilerbicidal formulations studied by Rowc and Hymas (17) Trade name 2,4-Dow weed killer (formula 40) Esteron 44 Esteron 246 (old formulation) Esteron 245 (present formulation) Esteron ton-ton Active Ingredients (percent) 66.0 Alkanolamino salts of 2,4-D 44.0 Isopropyl ester of 2,4-D 33.3 Isopropyl ester of 2,4,6-T: 12.1 Mixed amyl esters of 2,4,6-T 66.3 Mono-, di-, tripropylene glycol butyl ether esters of 2,4.6-T 70.5 Mono-, di-, tripropyleno glycol butyl ether esters of 2,4-D 27.2 Butyl esters of 2,4-D; 26.5 Butyl esters of 2,4,5-T 52.2 Butyl ostors of 2,4.5-T 37.1 Isopropyl esters of 2,4-D; 39.0 n-Butyl ester of 2,4-D Brush killer 50-60. Brush killer T Esteron 76 (used in oil solution only) Estoron 76E (used In cither oil solution or water emulsion) 36.8 Isopropyl esters of 2,4-D; 38.8 Butyl esters of 2,4-D Esteron brush killer (old formulaton) 25.6 Isopropyl esters of 2,4-D; 24.4 Isopropyl esters of 2,4,6-T [34.8 Mono-, di-, tripropyleno glycol butyl ether esters of Estoron brush killer (prcsont formulation I 2,4-D 133.0 Mono-, dl-, tripropylene glycol butyl ether esters of I 2,4,5-T Kurori (was called 11-1078) 64.5 Mono-, di-, tripropyleno glycol butyl ether esters of silvex Dow MCP aminc weed killer* 69.1 Alkanolamine salts of MCP *2-mothyl-4-chlorophenoxyacotic acid. Table 2 presents a summary of tho acute oral toxicities of the various herbicide components. TABLE 2.—Acute oral toxicities of various phcnoxy acetate herbicidal chemicals. Rowe and Hymas (17) Material Species Sex Vehicle l.d.50 (19/20 confidence limits) (mg./kg.) 2,4,5-T (2,4,5-Trlchlorophenoxyacetic acid). - Eats Mice Guinea pigs... Chicks. M M MandF.. MandF.. Olive oil Olivooil.... Olivooil.... Olive oil.... Dogs (4). Eats Guinea pigs... Mice Bat : . MandF.. F F F Capsule Olivooil Oliveoil Olivooil.-Cornoil 500 (391-640) 389 (245-619) 381 (307-472) 310 (211-466) Bange 100 (50-260) 495 (420-584) 449 (362-557) 5 "~ 4 Babbit Mice M F Cornoil Cornoil 712 (600°1,000) 940(674-1,312) 2,4,5-T, isopropyl ester 2,4,5-T, mixed butyl esters Guinea pigs... F 750 (50(M?000) Bango 750 (500-1,000) Bange MCP (4-chloro-o-toloxyacctio acid or 2- Eat M Com oil 700(500-1,000) Mothyl-4-chlorophenoxyaeotic acid). Bange MCP,aminesalt Eat. M Water....... 1,200 (1,000-2,000) Range Guinea pigs... M Water 1,200 (630-2,000) silvex, (2[2,4,6-trichlorophonoxy] propionic Eat M and F.. Corn oil 650(560-760) acid). Eango silvex, mixed butyl esters. Eat F Cornoil 600 (250-1,000) Range Babbits F Undiluted.- 760 (500-1,000) Chicks MandF.. Cornoil 1,190 (707-2,000) silvex, mono-, di-, tripropylene glycol butyl Bat F Cornoil 621 (473-814) other esters. Range Guinea pigs... M Cornoil 1,250 (500-2,000) 40 Corn oil Bats F Olivooil Mice Chicks Babbits 2,4,5-T, mixed amyl esters. F.___ Cornoil 1,410 (1*000-2,000) MandF.- Cora oil 1,190 (847-1,670) F Undiluted-. 819 (610-1,070) �Similarly, Howe and Hymas reported the results of oral feeding of several commercial formulations of 2,4,5-T and related compounds (Tablc3). TABLE 3.—Summary of oral toxicities of a variety of phenoxy acetate herbicidal formulations. Rowe and Hymas (17) l.d. m Material Species Sex Vehicle (10/20 confidence limits) (mg./kg.) 2,4-Dowwecdkillcr.-. Guinea pigs... F_ 2,4-Dow weed killer (formula 40).... Rats F Esteron44 Rats.... M Estcron 246 (old) Rats F Estcron 245 (new) Ksteron ten-ten Brash killer 60-60 Rats.. M._ Rats F Rats If Guinea pigs... F Mice F Brash killer T Rabbits . Chicks .. Rat Guinea pigs... Mice Rabbits -Chicks Range 2,000 (1,000 3,000) Range Water 850 (700 -1,000) Range Olive oil 050 (300 1,000) Range Emulsion in water.. 1,000(3002,000) Range Olive oil. 800 (000-1,000) Oliveoil 780 (060-860) Kmulsion ill water.. 1,070 (700-1,650) Emulsion in water.. 1,160 (820-1,030) Corn oil 800 (624-1,070) Range Undiluted 1,420 (600 2,000) Undiluted. 4,000 (2,700-5,900) Emulsion in water.. 1,200 (783-1,860) Emulsion in water.. 1,410 (876-2,290) Oliveoil 1,230 (938-1,620) Undiluted 849 (604-1,190) Undiluted 2,000 (1,350-2,960) Range Corn oil 750 (500-1,000) Range Corn oil.. 300 (2601,000) Range Emulsion in water.. 1,000 (300-3,000) Corn oil—. - - - - 860 (800030) Corn oil 1,220 (1,0401,430) Com oil 1,600 (1,390-1,840) Corn oil 960(790-1,160) Range Corn oil 2,000 (1,000-3,000) Undiluted. Greater than 1,000 -- Water F. MandF.. F F F M.. MandF.. Brash killer 76 Rats Brash killer 76E. Rats F F.. Esteron brush killer (old) Estcroii brash killer (new) Rats.. Rats Guinea pigs--Guinea pigs... Rabbits M__ MandF.. M___ F MandF.. Chicks Steers MandF.. Rowe and Ilymas concluded that the acute LD.-)0 for 2,4-D, 2,4,5-T, and their various formulations and combinations fell in the range of 300-1000 ing/kg. There was sonic variation among species with dogs appearing relatively more sensitive than other species of animals. Military applications of 2,4,5-T as a defoliant have utilized combinations of 2,4-D and 2,4,5-T in formulations known as Orange and Purple. There has been some acute lexicological testing of the mixture, Purple, on small animals. Purple contains 50 per cent butyl ester of 2,4-D, 20 per cent isobutyl ester of 2,4,5-T and 30 per cent n-butyl ester of 2,4,5-T. The details of this work have not been published but have, appeared in summary form in a review. (8) (Table 4) 41 �TABLE 4.—Acute animal ioxicity of Purple (8) Koutc Oral Intraperitoncal Percutaneous Dosages (ing/kg) Toxicity -- I/Dm LDi -- LDso LDi-. LDeo LDi-LDso LDi.-- Rat .... Rabbit 666 213 1, 094 686 121 363 66!) 244 . 5,502 12,034 3,178 493 Dog a600 >260 a 500 >260 >1, 260 a=approximation There have been a few accounts of testing for acute toxicity of 2,4,5-T on domestic animals (14, 17). Those indicated that repeated doses of 100 mg/kg of 2,4,5-T wore tolerated without overt signs of illness in sheep and steers. In one instance 1000 mg/kg/day proved fatal to a steer after the third day. 500 rng/kg/day provoked signs of acute toxicity in steers after the third day (17). The numbers of animals used in these studies wore very small (single animals in some cases). It has been assumed by some that the metabolism (and, hence, toxicity) of 2,4,5-T would resemble that of the other phonoxy acid herbicides. This is probably a reasonable assumption although it has not been systematically examined. There have been two recent reviews of the toxicity of phcnoxy acid herbicides (3), (19). Included in these reviews are accounts of acute human toxicity of 2,4-D. The accounts include incidents of excessive occupational exposure, suicidal efforts, intended oral feeding and parcnteral administration as a form of treatment for coccidioidomycosis From descriptions such as these, it has been inferred that around 50 to 100 mg/kg of 2,4-D is acutely toxic to humans. However, there are inconsistencies in this scanty information. Occupational Experience Occupational exposures (in the 2,4,5-T manufacturing process) have provoked illness in workers. However these effects have been attributed to the dioxin impurity (tetrachlorodibcnz-p-dioxin). (See Section III, Chemistry). The toxicity of this impurity is considered later in this section. National Cancer Institute Screening Study for Carcinogenesis and Teratogenesis In 1964, the National Cancer Institute contracted for a screening study of a number of pesticides. Among the purposes of this large scale examination was to determine whether compounds in common use might be tumorigenic, or teratogenic or mutagenic (12). The results of 42 �testing for carcinogcncsis have been summarized by limes ct al (9). The results of testing for tcratogenosis with 2,4,5-T have been analyzed and summarized by Courtney ct al (#). Screening for tumorigouicity was performed on two hybrid strains of mice. The materials, which were from commercial lots, were given by single subcutaneous injection or by continuous oral feeding. For each dose and each strain, 18 animals of each sex wore used. Oral feeding was started when the animals wore seven days old and was continued for 18 months. The dose chosen corresponded to a maximal tolerated dose. This was the experimentally determined maximum level resulting in zero mortality for 19 daily doses. The dose of 2,4,5-T used in the oral feeding studies was 21.5 mg/kg. Of the 72 mice which started the study, 12 died or were cannibalized before the end of the 18 months. Of those surviving, nine animals exhibited tumors. Of the total number nccropsied (survivors phis premature deaths), 12 animals exhibited tumors. These included 4 roticulurn coll sarcomas, 2 pulmonary adenomas, 5 hcptomas, and 1 benign calcifying epithelioma. Those results were compared with the tumor incidence in a group of untreated control animals and in a group of animals treated with known tumorigcns. 2,4,5-T was not found to provoke a significant increase in tumors after chronic administration. In addition to 2,4,5-T, several related phenoxy compounds were also screened for tumor production. Those compounds included: 2,4-D 2,4-D isopropyl ester 2,4-D butyl ester 2,4-D isooctyl ester a-(2, 4-dichlorophcnoxy) propionic acid a-(2, 5-dichlorophenoxy) propionic acid a-(2, 4, 5-trichlorophenoxy) propionic acid Three of these compounds administered by the subcutaneous route [«-(2,4-dichlorophenoxy) propionic acid; a-(2,4,5-trichlorophonoxy) propionic acid; and 2,4-D isopropyl ester] elicited an increase in tumor incidence in comparison with negative controls but the statistical significance was less than 0.02. Screening for tcratogcnic effects was performed on four strains of mice and, in the case of 2,4,5-T, on one strain of rats. 2,4,5-T was one of 53 compounds examined in this study. Other related agents included were: 2,4-D 2,4-D isopropyl ester 2,4-D butyl ester 2,4-D isooctyl ester 2,4-D methyl ester 2,4-D ethyl ester 43 �a-(2,5-dichlorophenoxy) propionic acid 2,4-dichlorophcnol 2,4,5-trichlorophenol 2,4,6-trichorophenol Compounds wore administered subcutaneously in solution of dimethyl sulfoxide in maximally tolerated doses to pregnant female animals. Administration occurred between the 6th and the 14th days of gestation in mice. The animals were sacrificed on the 18th day and the fetuses wore examined for abnormalities. With the finding of apparent increase in birth defects, the experiments were repeated with oral administration of the agents. Because of the finding of an increase in birth defects in the case of 2,4,5-T, this compound was studied more intensively (wider range of doses and two species of animals). Evaluation compared the influence of these chemicals on the total incidence of birth defect. In addition, a further analysis attempted to rcdxico the interlitter statistical influences by calculating the incidence of birth defects on a litter-by-litter basis (2) 2,4,5-T was tested in the C57BL/6 and AKR strains of mice, and in a hybrid strain produced by mating C57BL/6 females with AKR males. Three dosage levels (21.5, 46.4, and 113.0 mg/kg) were used orally and by injection. Numbers of litters varied from 6 to 18 in the experimental animals (6 to 12 in the orally fed animals). Three different patterns of dosage and sacrifice were used (dosage during days 6-14, 6-15, and 9-17). The findings from this set of experiments were increases in incidence of fetuses with cleft palate arid fetuses with cystic kidney when compared to controls. There was also an indication of a dose-response relationship. Table 5, reproduced from Courtney, et a/. (2) summarizes the findings. The numbers in the columns representing the percentages of abnormal fetuses per litter were derived by averaging the percentages of abnormalities per litter for each dosage. Because of these results, an additional series of experiments was conducted in Sprague-Dawley rats. Four dosage levels were used (4.6, 10.0, and 21.5 and 46.4 mg/kg). Two typos of fetal abnormalities were recognized, cystic kidney and enlarged renal pelvis. Courtney et al., (2) in reviewing these experiments, analyzed the results on the basis of abnormalities per litter. In reducing the sample size from the total number of fetuses to the total number of litters, these authors felt that the resulting sample size for the 21.5 mg/kg dosage was too small and, hence, deleted the data for this dose. Table 6 is a summary of these data. The inferences which have been drawn from these experiments are that 2,4,5-T appears to provoke a higher than expected level of fetal death and fetal abnormality in rats and mice in the dosages used. Further, there appeared to be a suggestion of a dose-response relationship over the range of doses used. 44 �Comments of the screening study contracted for by the National Cancer Institute have already been published (18). The following observations by the Panel are concerned with the portion of this study in which the tcratogenic potential of 2,4,5-T was tested. 1. The study involved a great number of variations in procedure (strain of mice used, dates when tests wore performed, and routes of administration). Those variations make the task of evaluation difficult. 2. Too few animals and litters of animals wore used. Since biological variability is considerable, the sample size must bo adequately large to demonstrate specific effects of the chemical agents in question. At least 10 pregnant females to assure at least 100 conceptions is suggested. The Food and Drug Administation suggests 20 females per tost group. 3. There appears to be an unusually high level of embryo lethality and teratogonicity among untreated and vehicle-treated groups. Either the experimental conditions were less than optimal or the strain of animals was dovclopmontally unstable. 4. The strain of mouse most often used (C57BL/6) appeared to have had undesirable traits as a tost animal, being variably and uncertainly responsive to the substance being tested. A reasonably homogeneous, colony-bred stock which has been maintained in the laboratory long enough for the investigator to have accumulated substantial background data on fecundity, spontaneous malformation and intrauterino death rates is generally regarded as preferable, to inbred stocks for teratological testing. 45 �TABLE 5.—Teratogenic evaluation of 2,4,6-T in mice Compound Vehicle Fetal Live mortalLitters fetuses ity per (No.) per litter litter (av. No.) (percent) Dose (mg/kg) AbPercentage of Abnormal fetuses per normal fetuses litter with: litters per litter (perCleft Cystic (percent) cent) palate kidney C57BL/6 strain treated days 6 to 14 Nontrcated Control Control 2,4,5-T 2,4,5-T 2,4,5-T 2,4,5-T None DMSO Honey DMSO DMSO Honey Honey 1Njoiio (*) 72 10G 32 G 18 6 12 (') 21.6 113.0 46.4 113.0 5.8 5.5 7.1 7.7 4.4 8.5 4.8 26 29 15 3 42 8 t47 38 42 41 50 t86 11 12 14 12 t57 J37 f70 71 30 flOO 31 g noo fioo <1 <1 0 1 2 1 t22 2 f23 f41 0 0 f2'J 7 0 o u f33 J48 C67BL/6 strain treated days 9 to 17 ... None Non treated Control . . .. DMSO 2,4,6-T. -. DMSO. None (*) 113.0 8 10 10 6.1 0.1 36 23 U 7.7 f77 teo AKR strain treated days 6 to 15 Nontreatod Control Control 2,4,6-T 2,4,5-T... None DMSO Honey DMSO Honey None.— (*) M 113.0 113.0 58 72 12 14 7 7.1 6.9 8.8 6.<J 5.3 16 15 23 }42 19 24 0 t71 tioo 5 4 0 t2<) t65 <1 <1 0 J56 <1 0 1 0 *Doso, 100 id per mouse. tP=.01. tP=.05. TABLE 6.—Teratogenic evaluation of 8,4,5-T in rats Compound Control.. 2,4,6-T 2,4,6-T 2,4,6-T Vehicle Honey Honey Honey Honey Dose (mg/kg) (t) 4.6 10.0 46.4 Average Percent Percent No. of No. live fetal abnorlitters fetuses/ mortalinal Utter ity/litter litters 7 14 8 7 6 9.9 8.7 8.2 7.1 2.7 11 1 12 *"28 «**69 43 57 88 86 67 Percent of fetuses Percent per litter with: abnormal Enlarged Cystic fetuses/ renal kidney litter pelvis 9 12 **3fi *»46 §60 9 12 11 17 27 0 <1 21 **30 §33 t200^1/rat(«). "Statistical Significance Level=0.06. "'Statistical Significance Levcl=0.01. §The sample size was possibly too small to show a significant difference. 5. It is puzzling that virtually no skeletal malformations were encountered in either controls or test group. Skeletal defects usually account for a substantial part of the easily detectable malformations that occur spontaneously or after treatment in rodent species. Hardly a strain that has been carefully studied in properly cleared and stained specimens has failed to show vertebral and rib variations. 6. There were some known teratogens used in these experiments (trypan blue, 6-aminonicotinamido). It is puzzling to find that these agents failed to produce significant tcratogenic and embryo-lethal effects consistantly. This raises questions about the precision with which these teratogcnicity tests were performed. 46 �7. 2,4,5-T appeared to bo clearly teratogonie in two strains of mice treated with 2,4,5-T at 113 ing/kg via either of the two routes of administration. In rats, 2,4,5-T appeared only equivocally teratogcnic at any dosage but clearly embryo-lethal from 10.0-46.4 mg/kg. 8. The lack of an unequivocally defined doso-rosponso relationship renders those results less than completely satisfying. Reports of Birth Defects Among Humans Following Exposure to 2,4,5-T Shortly after the report of the toratogoncsis screening in experimental animals of pesticides, there appeared a series of articles in the lay press which described the occurrence of birth defects in parts of Vietnam where defoliants had been used. These articles appeared in at least six different newspapers in South Vietnam between June 26 and July 5, 1969. Both congenital abnormalities and hydatid moles* wore described. Translations of the articles have alluded to the possibility that defoliants might bo responsible for these defects. The implication was offered that these abnormalities had increased in frequency in the recent past. No documentation has boon available. Toxicity of Dioxin It was pointed out in an earlier section of this report that one of the impurities which arises in the manufacturing process of 2,4,5-T is 2,3,7,8-tetrachlorodibcnzo-p-dioxin. This substance has considerable interest because it is highly toxic, because a close relative was a toxic constitutent in chicken feed and because it has caused chloracno, a severe skin disease, among workers engaged iti the manufacture of 2,4,5-T. The dioxin impurity has assumed a further importance as an impurity in commercially available 2,4,5-T. With the observation that production lots of 2,4,5-T containing approximately 27 ppm dioxin could be teratogcnic, it became important to ascertain whether it was 2,4,5-T itself or some impurity which was the teratogcn. Recent experiments at the National Institute of Environmental Health Services indicate that partially purified 2,4,5-T «0.1 ppm tctrachlorodibonzo-p-dioxin) shows toratogonic activity in the mouse. Pure tctrachlorodibenzo-p-dioxin shows toratogonic activity also, but not at low enough doses to account for the activity of the partially purified 2,4,5-T. We cannot exclude the possibility that other impurities may contribute significantly to the observed toratogenic activity of 2,4,5-T. *(Aii abnormality of pregnancy which involves the placenta and the membranes surrounding the fetus.) 47 �In the following paragraphs, the history of the discovery of dioxin is examined in relation to the experimental observation of the teratogenic properties of 2,4,5-T. Secondly, data on the toxicity of this material are presented. In March 1949, an accident occurred at a 2,4,5-T plant owned by the Monsanto Chemical Company which led to the release of some of the intermediate chemicals into the plant. As a result, 117 cases of a severe skin disease known as chloracno were found among the exposed workers. Chloracno is characterized by comedones, blackheads, inclusion cysts, and pustules with eventual scarring over the nock, back, and chest. In addition to the cases which were traced to the accident, a number of other clinical cases of chloracno wore recognized among workers in the 2,4,5-T plant who wore not in the vicinity of the accident. (10) Kimmig and Schulz (11) reported in 1957 that chloracno occurred among workers engaged in the manufacture of 2,4,5-T in Germany. Those authors demonstrated that the agent responsible for chloracno was totrachlorodioxin. In 1964, the demand for 2,4,5-T in tho United States began to rise mainly duo to its increasing use as a defoliant in Vietnam. A greater demand was placed on each of the domestic manufacturers to produce more herbicide. Coincident with tho increased production was the discovery of chloracno among some 60 2,4,5-T workers. (7) Tho Dow Chemical Company reduced its operations substantially for a period of several months in order to investigate the origin of tho toxic hazard. It was found that the amount of dioxin formed varied with the temperature and pressure of the early reaction stops. Tho Dow Chemical Company made its findings known to tho other domestic manufacturers. Looking back it is evident that dioxin levels varied widely among commercial 2,4,5-T samples, as scon in Table 4 of Section III. Eigorous control is now exorcised to reduce dioxin levels in the final product to loss than 1 ppm. A recent review of occupational disease attributed to dioxin has been prepared by Poland et al (15). These authors studied 73 male employees in a 2,4,5-T factory, some of whom had boon observed six years previously by Blcibcrg (1) who then noted the prevalence of chloracno. Poland ct al (15) also found chloracne among the same population although estimates of exposures were not made. Poland attributed the chloracno to tho dioxin impurity. They also examined the prevalence of a typo of porphyria, thought to bo toxic in origin, known as porphyria cutanca tarda (elevated urinary porphyrin excretion, skin fragility and vesicular eruptions). Uroporphyrinuria had boon noted during the early visit to tho plant by Bleiborg (1) but it was not found during the later study. Elevated urinary coproporphyrin levels were noted, however, but there appeared to bo no correlation with tho severity or presence of chloracno (1, 15). The later series of observations found much of tho chloiacnc still remaining 48 �but the porphyria had disappeared. Chloracno was attributed to the dioxin impurity but the origin of the porphyria was loss certain. In order to measure the toxicity of the dioxin impurity, the Dow Chemical Company undertook a scries of acute toxicity studies on small animals in 1967 (16). Single doses of 2,3,7,8-totrachlorodibonzop-dioxin wore administered orally to lots of five animals for each of several doses. The number surviving and the time of death were noted. The animals used were male rats, female rats and female guinea pigs. Table 7 gives the results of these experiments: TADLE 7.—Single-dose oral toxicity of dioxin (IS) Species Malorat Female Female guinea pig LUsn ing/kg rat 0.022 0.045 O.OOOfl With this background in mind, the purity of the 2,4,5-T material used in the National Cancer Institute screening study assumed a now importance. A sample of this material was submitted to chemical analysis by gas chromatography. The result was the finding of 27 ± 8 ppm of dioxin. Testing for Teratogenicity The study of teratogonic effects in experimental animals is characterized by a great deal of empiricism. However, in general testing for tcratogcnic potential is a more manageable problem than arc a number of other typos of biologic testing. There arc largo numbers of agents known to be toratogonic to animals. In fact, it has been held that virtually any material is potentially teratogenic if administered in an appropriate doso at the critical time in gestation. Interestingly, however, only a few chemicals have been recognized as human toratogcns. In general, an embryo-toxic dose of a material is separated from a maternal toxic dose by a small margin (perhaps no more than a factor of 10). Only slightly below the embryo-lethal or toxic dose is a iio-cffoct dose (separated, perhaps, by a factor of 2). Between the highest level which has no effect on the developing fetus and the embryo toxic level is a steep dose-response relationship. In testing for tcratogcnicity, the lowest dose on the dose-response curve (threshold for any embryo toxicity) is identified. All doses below this level are, by definition, no effect doses. By accepting an extra margin of safety below this dose (a factor of 1/10-1/100), reasonable freedom from teratogenic effects can be predicted. A problem arises in extrapolating findings in experimental animals to man. The ombryotoxicity of a chemical agent is, in theory, a function 49 �of the degree of exposure of the developing embryo to the agent. This appears to bo a function, in turn, of the persistence of the material in the maternal circulation. Thus, in order to extrapolate animal findings to humans, the animal must bo "calibrated" to humans for each chemical agent. That is, the rate of disappearance of the agent from the animal circulation must be compared quantitatively to that in humans. As a first approximation, corresponding doses in mg/kg would be taken as proportional to the blood clearance rates for tho two species. These principles make possible tho design of testing procedures for reproductive defects caused by chemical substances. Tho scheme described is of a general nature but can be applied to 2,4,5-T. Tho first step involves determination of the chemical nature of tho material in question. Secondly, animal studios should bo done to establish embryo toxic levels. In the case of 2,4,5-T, some additional studies have boon carried out to confirm tho results of tho National Cancer Institute screening study. In addition, studies should bo undertaken on pure 2,4,5-T and on its various impurities to identify tho teratogcnic agent or agents. Hybrid strains of animals should bo used rather than highly inbrod strains. At least two animal species should be used. Preferably strains of colony or random bred rats and mice should be used which have been maintained in tho laboratory long enough for tho investigator to have accumulated substantial background data on fecundity, spontaneous malformations and intrauterine death rates. By careful testing, using a small series of doses, a TD60 dose (that dose which will cause teratogenosis in 50 percent of fetuses) can be ascertained. At the low end of tho doso-response curve is found, presumably, a threshold dose below which no detectable tcratogonic effects would bo expected. Actual experimentation locates TD sman at which teratogenicity occurs in only a few percent of all fetuses. The next stop is to compare tho expected human exposure with the animal TDgmai!- If these differ by as much as a factor of 100, it would seem reasonable to consider tho material safe with regard to teratogenosis. If the difference between tho human exposure and the animal TDsmai; is as little as a factor of 10, the margin probably is insufficient. Between 100 and 10 lies a certain amount of flexibility for further action. Finally, in order to extrapolate tho animal data to human experience, rates of excretion and detoxification in animals and humans should bo compared. Summary of Recent Experiments Following analysis of the results of the screening study carried out for the National Cancer Institute, it was felt that confirmatory studies should be undertaken. Two sots of experiments were begun independently by the Dow Chemical Company and by the National 50 �Institute of Environmental Health Seienccs. At the time of this writing, somo of those experiments have been completed and the results have been reported. 1. Dow experiments. 2,4,5-T (containing 51.0 ppm dioxin) was administered orally to pregnant Spraguo-Dawloy rats on days 6-15 of gestation. (6) The doses used were 1, 3, 6, 12, and 24 mg/k'g/day. The 2,4,5-T was administered in 0.25% Mcthocol®. The results were compared with those obtained from controls which received the vehicle only. No clinical or gross pathologic signs of adverse effect were observed in ticatcd females during the period of treatment. Litter size, number of fetal rcsorptions and birth weights appeared to be unaffected. Furthermore, there was no increase in the incidence of birth defects compared to control animals. In a related study by the Dow Chemical Company on the tcratogenicity of 2,3,7,8-tctrachlorodibcim>-p-dioxin (4), this material, in pure form, was administered to pregnant Sprague-Dawloy rats. The doses used ranged from 0.03 to 8.0 mg/kg/day. Between 0.125 and 0.5 mg/kg, intestinal hemorrhages were seen in the fetuses. Dioxin was very embryolethal at the highest dosages (2.0 and 8.0 mg/kg). 2. NIEIIS experiments. The National Institute of Environmental Health Sciences undertook a scries of experiments in which 2,4,5-T (containing various amounts of dioxin impurity) was administered to pregnant mice and rats (13). Three strains of mice were used (1 random bred and 2 inbred stains) and a random bred strain of rats. Four different lots of 2,4,5-T were employed: a. "Eastman Organic"—contained 5 1.0 ppm dioxin. b. "Dow Technical"—contained 5 0.5 ppm dioxin. c. "Dow Pure"—contained 5 0.1 ppm dioxin. d. 2,4,5-T samples used in the original tests performed for the National Cancer Institute—containing about 27 ppm dioxin. In addition, pure 2,3,7,8-tetrachlorodibenzo-p-dioxin was administered to a scries of mice and rats. These materials were tested in various dosages in mice by injection in dimethyl sulf oxide (DMSO). In the random bred (Charles River) mice, the dosage schedule for 2,4,5-T covered the range of 50-150 mg/kg/day. In the other strains of mice, a narrower range; of doses was tested. In rats, the dosage range was 10.0-21.5 mg/kg/day and here the material was administered orally in sucrose. Pure dioxin was administered subcutaneously in DMSO in rats and mice (1 and 3 mg/kg/day in mice and 0.5 and 2 mg/kg in rats). In mice, both 2,4,5-T (in the purest form available) and dioxin produced birth defects and increased fetal toxicity. The birth defects were qualitatively similar to those seen previously in the National Cancer Institute screening study and included cleft palates and 51 �renal defects. In rats renal defects and excess fetal mortality were seen but seemed to bo related to dioxin content rather than 2,4,5-T. 3. FDA Experiments (unpublished data acquired in the spring of 1970). Tcratogonic studies were performed by giving the test compound by oral intubation to pregnant hamsters on day 6 through. 10 of organogcncsis. Embryos were removed by cacsarian section on day 14 of pregnancy. Samples of 2,4,5-T tested wore: a. "Dow Technical"—contained ^ 0.5 ppm dioxin. b. "Dow Technical"—contained ^ 0.1 ppm dioxin. c. "Dow Pure"—contained ^ 0 . 1 ppm dioxin. d. Hercules X-17394—contained no detectable dioxin. e. Monsanto NL-07-020—contained 2.9 ppm dioxin. f. "K & K" sample—contained about 45 ppm dioxin. g. Eastman Kodak (rocrystallizod in FDA)—contained no detectable dioxin. In addition pure 2,3,7,8-tetracolorodibenzo-p-dioxin (Dow) was administered to hamsters. These materials were tested in various doses from 40-100 mg/kg. All of the 2,4,5-T samples produced increased embryotoxicity and gastric and/or intestinal hemorrhages. Birth defects consisted chiefly of poor head fusion and absence of eyelids. The pure tetradioxin produced increased fetal toxicity at 0.31 and 1.43 Mg/kg and gastric and/or intestinal hemorrhages at the lowest dose, 0.02 /ig/kg. REFERENCES (1) BLBIBEEG, J., W ALLEN, M., BRODKIN, R., and APPELBAUM, I., Arch. Derm £9:793, 1964 (2) COURTNEY, K. D., GAYLOR, D. W., HOGAN, M. D., and FALK, H. L., Tcratogenic evaluation of 2,4,5-T. Manuscript submitted for publication (1970) (3) DALGAARD-MIKKELSEN, S. and PAULSEN, E. Rev. 14:215, 1962 (4) Dow Chemical Company, personal communication (6) DRILL, V. A. and HIHATZKA, T. AMA Archives of Industrial Hygiene and Occupational Medicine, 7:61, 1953. (6) EMERSON, J. C., THOMPSON, D. J., GERBIG, C. G., ROBINSON, V. B. Teratogenic study of 2,4,5-trichlorophenoxy acetic acid in the rat. Presented at the meeting of the Society of Toxicology, Atlanta, Georgia, March 17, 1970 (abstract) (7) HOLDER, B., Occupational Medicine Department, Dow Chemical Company. Personal communication. (8) HOUSE, W. B., GOODSON, L. II., GADBBHRY, II. M., and DOCKTER, K. W., Assessment of ecological effects of extensive or repeated use of herbicides. Midwest Research Institute. Project No. 3103-B. December 1967. (9) INNES, J. R. M., ULLAND, B. M., VALERIO, M. G., PETRUCELLI, L., FisnBEIN, L., HART, E. R., PALLOTTA, A. J., BATES, R. R., FALK, II. L., GAST, J. J., KLEIN, M., MITCHELL, I., and PETERS, J., J. Nat. Cancer Institute 42:1101, 1969. 52 �(10) Kottcring, Laboratory, Unpublished reports. Department of Preventive Medicine and Industrial Health, College of Medicine, University of Cincinnati, Cincinnati, Ohio. (11) KIMMIU, J., and SCHULZ, K. ])., Dermatologica 115:MQ, 1957. (IS) National Cancer Institute. Evaluation of the carcinogenic, tcratogonic and mutagenic activities of selected pesticides and industrial chemicals. 4 vols. Bionctics Research Laboratories, 7300 Pearl St., Bethesda, Md., 1967. (IS) National Institute of Environmental Health Sciences, unpublished data. (14) PALMEU, J. S. and RADELEFF, R. I)., Ann. N.Y. Acad. Sci. 3:728, 1964. (15) POLAND, A. P., SMITH, D., MGTTES, G., and FOSSICK, P., A health survey of workers in a 2,4-D and 2,4,5-T plant: with special attention to chloracnc, porphyria cutanea tarda and psychologic parameters. Manuscript in preparation, 1970. (16) ROWE, V. K., Personal communication, 1970. (17) ROWE, V. K. and HYMAS, T. A., Amer. J. Vet. Res. 15:ti'22, 1954. (18) U.S. Department of Health, Education, and Welfare, Report of the Secretary's Commission on Pesticides and Their Relationship to Environmental Health, December 1969. (19) WAY, J. M., Residue Rev. #6':37, 1969. 53 �RESIDUES OF 2,4,5-T IN THE ENVIRONMENT Summary 2,4,5-T residues disappear from soil with moderate speed, probably through action of microorganisms, persisting as long as three months. During this period they are potentially available for transport to non-target areas. It appears unlikely that residues from recommended applications of 2,4,5-T could appear in hazardous quantities in water. Typical applications are to forested areas or those infested by weeds where most of the herbicide appears to be intercepted by the plants. Residues do not seem to persist in water, however, they do remain longer in bottom sediments. Residues from rangeland and pasture applications may find their way into cattle permitted to graze soon after spraying. Cattle excrete the intact herbicide rapidly but 2,4,5-T residues have occasionally been found in meat and dairy products. Although the residue levels are low, they dictate caution about pasturing soon after rangeland treatment. The rate of application of 2,4,5-T in Vietnam is 13 Ibs. of the butyl ester per acre (26 Ibs. of Orange per acre). This rate is about 2-6 times as high as that used on rangelands domestically. Moreover, much larger areas are treated in Vietnam. Orange is not used on food crops but on forests. Hence, human exposure to contaminated food crops would be unlikely. If, during the vulnerable period of gestation, all a pregnant mother's food came from locations treated with Orange at 26 Ibs/acre within the preceding week or so, the daily dose of 2,4,5-T might conceivably reach 15 mg/kg/day, which by comparison to some animal data might prove to be embryotoxic. Such estimates are based on a very extreme, worst-case calculation. Residues of 2,4,5-T resulting from recommended uses in the United States The herbicide 2,4,5-T is applied for weed control to a relatively few crops. However, it is used more extensively for control of weeds in rangelands and pastures, non-croplands and aquatic areas (Table 1). 54 �It is not considered to be a persistent pesticide by comparison with many of the chlorinated hydrocarbon insecticides. Nevertheless, its use at rates of recommended application results in measurable levels of residue in soils, water, air, plants, and animals which persist for relatively short periods of time after application. The potential effects of such residues on the health of man and other animals have been little studied and arc poorly understood. Data available suggest that residues resulting from recommended rates of application arc not of sufficient magnitude to justify concern as potential health hazards. Unfortunately, most of the toxicity studies conducted thus far have been relatively short-termed and of value for determining acutely toxic doses only. Substantial amounts of data are available of the sort reported by Palmer and lladclcff (14). Data from such studies indicate that 2,4,5-T is not acutely hazardous for cattle, sheep, and chickens when applied at recommended rates. They considered rales of application above 30 pounds per acre to bo hazardous. Recent concern over the possible adverse; effects of long-term exposure to relatively small amounts of 2,4,5-T as residues in food, feed, and water makes it desirable to review the information available on levels and persistence of such residues. 1. Soils—The possibility of residual toxicity to crops grown on soils trcalod with 2,4,5-T has emphasized the need for information on the levels of residues resulting from various rates of application and their persistence. Substantial amounts of data have been accumulated on these points and there is relatively good agreement in results of most studies. Taking into account differences in soil type, temperature, and moisture arid the phenomenon of bacterial proliferation in response to a now substrate, it appears that 2,4,5-T residues in soils may persist for as long as three months. The persistency of residues seems to be independent of the rate of application. TABLE 1.—Some examples of domestic uses of 2,4,8-T for control of weeds. (Suggested guide for weed control, 1969). U.S.D.A. Agriculture Handbook No. 332 Rate of application, pounds per A Crop or area Sugarcane Grasses grown for seed _ _ _ __ _ Rice. Permanent pastures and rangolands _ _ _ Non-cropland, rights-of-way, floodways, ditclibanks, fanco rows, and industrial sites Aquatic weeds _. _ _ 1.0 0.76 0.5-1.6 0.6-8.0 1.0-4.0 1.0-4.0 Laboratory studies suggest that breakdown of 2,4,5-T residues in soils result from the action of microorganisms which are capable of using these chemicals as sources of energy arid carbon. Two species have been reported to use 2,4,5-T as a source for energy and carbon. (1) The microbiological degradation of the phenoxyacetic acid herbicides in Ihe forest floor material probably resembles that in soils. (IS) 55 �Under the conditions of this environment substantial amounts of 2,4,5-T remained after 4 months. The relatively rapid degradation of residues of phenoxyacetic acid herbicides in the soil makes it unlikely that there will bo any accumulation of 2,4,5-T from one season to the next. Rates of removal from soils by plants and invertebrates arc uncertain. A major concern about residues of persistent pesticides is that they do not always stay in the target area. The fact that residues of 2,4,5-T may remain in the soil for periods of throe months, or more, makes it subject to transport to non-target areas. Soil particles contaminated with 2,4,5-T may bo transported by wind or water to areas far removed from the site of application. The extent to which this occurs seems to have received little or no attention. The choice among esters is often influenced by such considerations as reduced volatility (which may reduce spreading to non-target plants), slowness of hydrolysis, and avoidance of crystallization after the vehicle has evaporated. Experiments on leaching of 2,4,5-T products and vehicles suggest that amino salts arc leached more rapidly than the free acid (8). 2. Water—Residues of pesticides in water arc of concern because of the possibility of their getting into drinking water for man and other animals, of their potential adverse effects on aquatic organisms, and of the potential adverse effect on sensitive crop plants of irrigation water contaminated with these chemicals. Contamination of surface waters with herbicide residues is a matter of special concern since surface water provides most municipal water supplies. Nearly all of the water for livestock and other animals is supplied from surface water. Since nearly 100 million acres of land are treated with herbicides in the United States each year, about 3 million acres of which arc forest or rangelands, it is inevitable that substantial contamination of surface waters occurs. However, most of the contamination is indirect as a result of drift from target areas. The manner in which contamination occurs, whether from drift or from direct application, determines the level of residues deposited. In applications made to forested areas or to bodies of water heavily infested by weeds extending above the water, much of the toal amount of herbicide applied will not reach the water directly. As much as 88 percent of the total amount applied may be intercepted by such plant covers as livcoak which arc much less dense than those of water hyacinth or alligator weed. (16) There appears to bo little information available on the possibility of future release to water of residues in plants. Streams in forests in Oregon sprayed with 2,4,5-T or mixtures of 2,4,5-T and 2,4-D in a 1:1 ratio at the rate of 2 pounds per acre showed maximum residues of 70 ppb which disappeared within 17 days. (Id) 56 �Even at the heaviest rate of application recommended for control of weeds in permanent pastures and rangelands and aquatic species, 2,4,5-T residues would not be substantial oven at the maximum levels that could be expected. For example, 8 pounds of herbicide per acre applied to a body of water 3 inches deep would result in residues of only 12 ppm, Table 2. An animal drinking from even such an unusually shallow source could not get a dose that would be expected to cause chronic toxicity. For example, a cow weighing 500 kg may be expected to drink as much as 50 1. of water per day during the warm seasons of the year which would result in the ingcstion of about 1.2 mg/kg/day. However, a more realistic example could bo expected from applications of 2,4,5-T to rangelands at 4 pounds per acre. Treatment of a body of water one foot deep at this rate would result in residues of only 1.5 mg/1. A 500 kg cow drinking from such a source could get no more than 0.15 mg/kg/day. Adverse effects of residues of 2,4,5-T on aquatic species such as fish and some of the bottom dwelling invertebrates might be expected from the heavier recommended uses of this herbicide to shallow bodies of water. For example, 24-hr. LCSO* for blucgill is 1.4 ppm for the butoxyethanol ester of 2,4,5-T (see table 1 on page 67). Concentrations higher than this would result from the direct application of 4 pounds per acre to bodies of water no more than 6 in. deep. TABLE 2.—Estimated maximum level (mg./L) of residues of 2,4,5-T at various rates of application to bodies of water ranging from 3 inches to 10 feet in depth. Rates ol application, pounds per A Depth of Water 3 inches 6 inches Hoot 2fcet 3 feet 4feet 5 feet 6 foot 7fcot 8 feet Ofoct lOfeet. 2 1.5 0.75 0.38 o.io 0.13 0.09 0.08 0.06 0.05 0.05 0.04 0.04 4 0 20 3.0 1.50 0.75 0.38 0.25 0.10 0.15 0.13 0.11 0.09 0.08 0.08 6.0 3.0 1.60 0.75 0.50 0.38 0.30 0.25 0.21 0.19 0.17 0.15 9.0 4.50 2.25 1.13 0.75 0.56 0.45 0.38 0.32 0.28 0.25 0.23 30 0 IS 00 7 50 3 75 2 50 1 88 1 50 1 25 1 07 0 04 0 83 0 75 26 80 3 t 0 120.0 1 1,50 60.0 1.75 30.0 .88 15.0 :. 25 10.0 7.50 !.44 .95 6.00 5.00 .68 4. 29 .Sit .22 3.75 3.33 .08 3.00 ().'J8 100 150.0 75.0 37.60 18.75 12.60 9.38 7.50 6.25 5.36 4.6<J 4.17 3.75 There appears to be little likelihood of 2,4,5-T appearing in hazardous quantities in ground water or drainage channels from local applications. Brown and Nishoka (3) reported that 2,4,5-T was not detectable in samples of water-suspended sediment mixtures from 11 streams in the western United States. However, a subsequent study of the same streams (11) making use of improved techniques showed 28 of 235 samples taken from 17 rivers during 1966-68 to be positive for 2,4,5-T residues. Twenty-one of these *LCto, median lethal concentration of a toxicant, typically placed in the ambient environment of the organisms whose survival is measured. Usually, the environment in question is aquatic. The terms, LDso and LCso, may be used interchangeable for aquatic organisms. 57 �were from three rivers, the Arkansas, Brazos, and Canadian. All of the seven samples taken from the latter were positive. The amount of residues found was extremely small, ranging from 0.01 to 0.07 ppb. Samples were taken uniformly throughout the year and there appeared to be little effect of season on incidence or levels of 2,4,5-T residues. Samples were analy/cd as received with no effort made to separate water and sediments. It is possible that a high percentage of the residues was contained in the sediment since there is evidence that phonoxyacotic acid herbicide residues persist longer in sediments than in water. In either case, those data provide strong evidence that residues of 2,4,5-T in water which result from use of the herbicide in this country are not ha/ardous. 3. Plants—The levels of residues of 2,4,5-T in plants have received much less attention than has been devoted to insecticide residues. The comparatively short residual life of this material together with the fact that it is usually applied several weeks, or even months, in advance of harvesting dates, has allowed it to be used in most cuses without danger of significant residues in the harvested product. However, it is recommended for control of weeds in permanent pastures and rangelands at rates which result in significant levels of residues that have been reported to persist, under some conditions, for as long as 6 weeks, Table 3. However, there has been relatively good agreement in results obtained by various workers who have reported on persistence of residues of 2,4,5-T applied to forage grasses in rangelands and pastures. The data of Morton, et al. (12) indicate levels in pasture grasses ranging from 10 to 32 ppm after about one month which agrees reasonably well with the 7 ppm reported by Baur, et al. (2) in range forage grasses. TABLE 3.—Rate of disappearance of %,4,6-T residues from various types of forage crops. Estimated from semi-logarithmic plots in Figures 1-4- (18) Concentration, ppm (2,4,5-T) No. days from treatment 0 2 4.. 7.. 14 21 28 35 42 49 56 63 70.. 77 84 91 98 58 2 pounds per A teu- 2 pounds toxyethyl- per A acid ester 1 pound per A amine 300 . . . . - .. . 100 100 130 70 -55 45 32 20 12 7 70 35 20 15 12 11 11 11 8 7 6 5 4 3 70 45 30 15 10 8 6 5 4 3 3 2 2 2 �Substantial levels of residues occur in forage plants treated with 2,4,5-T at 2 Ibs/acro, and appreciable quantities sometimes persist for as long as 3 weeks. This suggests that beef cattle permitted to graze pastures or ningelands immediately after treatment, or that diary cattle permitted to graze such areas 7 days after application at maximum rates recommended, may be exposed to dosages that are too high for safety (Table 4). Estimates of the levels of residues that might occur in forage grasses treated at higher rates indicate a possibility of transfer of residues to milk and even chronic toxicity (Table 4). However, the fact that no evidence of toxic effects has been reported and that residues of 2,4,5-T have been rarely found, and oven when found have been at very low levels in dairy products that have been analyzed by FDA in total diet studies, argues against the probability that residues of this herbicide in forage crops pose any significant hazard. TAHLE 4.—Estimated rates of disappearance of 2,4,6-T residues from forage treated at different rales with corresponding maximum amounts of herbicide that might l>o ingested by cattle pastured on forage treated at the rates -Indicated. 2,4,5-T butoxyelhylestcr No. weeks after treatment 2 Ibs/A >> 4 lbs/A < mg/kg in mg/kg/day .1 ing/kg in nig/kg/day <i forage ingested forage ingested 300 130 70 0" 1 2 8 ... 4 5 6. 7 g . . . . . . 55 45 32 20 12 7 26 11 0 4 4 3 2 1 06 600 260 140 110 90 64 40 24 14 50 22 12 g g 6 4 2 1.2 0 Within 11 30 mill, of treatment. Estimated from semilogavithniic plots of graph in Table 2. (/«) ' Extrapolated from i> using maximum rates of 2,4,5-T recommended for permanent pastures and rangelands in Agriculture Handbook No. 332,1969. J Assuming a 600 kg cow eating 45 kg forage per day. 4. Animals—Residues of 2,4,5-T in animals, as in plants, have received much less attention than some of the fat soluble, longpersisting orgaiiochlorine insecticides. The residues that occur from ingcstion of the phonoxy herbicides arc eliminated rapidly and there is evidence that accumulation occurs in only a few species. Erne (6) in one of the most thorough studies of the distribution and elimination of 2,4,5-T reported that it was readily absorbed and distributed completely in the body. He found that it was eliminated rapidly. Plasma half-life values from single oral doses of 100 mg/kg of the amino salt to male rats and pigs were 3 and 10 hours, respectively. Highest levels of residues were found in the kidney, liver, lungs, and spleen with levels sometimes exceeding plasma levels. There was little evidence of penetration into the brain or adipose tissues. The main 59 �excretory route was the kidney. His data (7) showing weak but "certain" protein binding of 2,4-D suggest that this may also occur with 2,4,5-T. 5. Food and feed—Results of studies of pesticide chemical residues in total diet samples by the Food and Drug Administration during the period 1964-68 provide convincing evidence that 2,4,5-T residues are not a significant health hazard in food in the United States. During this 5-year period 30 composite samples of about 82 food items each have been collected each year from retail markets in 25 or more cities. Each composite sample, representing a 2-wook diet for a 16- to 19year-old male, is analyzed by multiresiduo methods for more than 60 chlorinated organic and organophosphorus insecticides and for herbicides, carbamates, and selected inorganic chemical residues. Examination of these samples is carried out at levels of sensitivity much lower than those normally used for products tested for compliance with tolerances. Data reported for the period Juno 1967-April 1968 (4) show incidence and levels of 2,4,5-T residues that are typical. Only one sample of diary products was contaminated. About 2 percent of diary products and 1 percent of meat, fish, and poultry wore reported to contain residues of 2,4,5-T. All of these residues were at trace levels, below 0.01 ppm. No residues of 2,4,5-T wore found in any of the other 10 classes of foods. It is significant that residues of 2,4,5-T wore detected only in foods of animal origin. The most likely source is forage from pastures and rangclands treated with 2,4,5-T for weed or brush control. Duggan and Lipscomb (5) summarized the results of sampling for herbicide residues in prepared food from the totat diel studios ovor a period of four years. From these studios, they estimated the likely dietary intake of all of the herbicides searched for to below: Year 1965 1966 1967 1968 Estimated dietary intake (mg/kg/day) 0.0012 0.00022 0.00005 0.00006 Since 2,4,5-T residues are only a small percentage of these total herbicide residues found in foods it seems safe to conclude that thcro is little likelihood of exposure from this source. Residues of 2,4-D and 2,4,5-T resulting from recommended uses by the military for defoliation. All the available evidence indicates that 2,4-D and 2,4,5-T behave similarly in animals with respect to absorption, distribution, motab60 �olism, and elimination. Since mixtures of these herbicides are used in the defoliation program in Vietnam, it does not appear reasonable to consider them separately. The large-scale; application of 2,4-D-2,4,5-T mixtures for defoliating military target areas in Vietnam poses some possibly unique hazards to humans. Application rates of about 26 Ibs/acro of a 1:1 mixture of the n-butyl esters of the chemicals are generally heavier than those used for agriculture and brush clearing in the United States. (There have been a few, limited applications of 2,4-D reported to lakes, streams, and reservoirs in the United States at rates of 80-100 Ibs/ acre for aquatic weed control.) There arc other differences. There arc vastly greater areas involved in Vietnam. Because of the nature of the military targets—heavily wooded, jungle areas—it is not likely that many crops are grown in or near treated areas. Although defoliation procedures appear to be under rigid control with all reasonable precautions taken to prevent application to crops, the nature of military operations makes it likely that accidents may occur and that mistakes may be made which result in direct applications to nontarget areas. In such cases it is possible that food crops and water supplies in restricted localities could receive heavy doses of the 2,4-D-2, 4,5-T mixture. A much more likely possibility is drift of relatively small amounts of the herbicides to non-target areas. The n-butyl esters of both 2,4-D and 2,4,5-T are volatile and substantial amounts of both chemicals may vapori/o at temperatures prevalent in Vietnam and escape from the target area. If mixtures of 2,4-D and 2,4,5-T were applied directly to food crops at the rates being used in Vietnam for defoliation (about 26 Ibs/acrc), it is theoretically possible that amounts potentially hazardous to humans could be deposited on food. The butyl ester of 2,4,5-T applied to an improved pasture at the rate of 2 pounds per acre was found to result in an initial deposit of about 300 ppm on the forage (12). Direct application to food crops at 26 pounds per acre could not reasonably bo expected to result in initial residues greater than 3900 pi:m. Assuming initial residues on food crops as high as 3900 ppm from direct application at the rate of 26 pounds per acre is unrealistic. Such an assumption requires that: 1) surface/volume ratios of food items be similar to that of forage, grasses; 2) all portions of food items, e.g., husks of corn, peels of banana, shells of coconut, be consumed; 3) there is no loss of herbicide during preparation and cooking; and 4) translocation of herbicide into portions of the plants used for food, e.g., root crops, banana pulp, and coconut flesh and milk, results in residues as high as if these portions had been treated directly. None of those is true. Some items of food could not be contaminated by direct contact with the spray formulation. Translocation from foliage to underground roots of sweet potato and fruits of peanut 61 �and into aboveground fruits such as coconut would bo required for these foods to be contaminated. Table 5 breaks down an estimated diet for a 60-kilogram Vietnamese into throe parts according to the rapidity with which 2,4-D and 2,4,5-T might be translocated into the portions consumed for food. Table 6 estimates the maximum believable concentrations of the herbicides in such a diet as being 3900 ppm initially, 1560 ppm after one week and 910 ppm after 2 weeks (See Table 2 for estimated rates of disappearance of 2,4,5-T residues from forage). The maximum dosage retained, substantially greater than any realistic figures, is about 30/mg/kg/day. TABLE 5.—Estimated for a 60-kilogram Vietnamese divided into three groups based on the rapidity with which 2,4-D and S,4,B-T,might be translocated into portions consumed for food.1 A. Foods into which very rapid movement is possible, not necessarily probable, and maximum concentration is attained immediately Dietary portions consumed g/person/day Leafy green vegetable Other vegetables Condiment vegetable Bananas Other fruits 52 196 40 107 75 Total 470 B. Foods into which moderately rapid movement is possible, though not necessarily probable, and maximum concentration is attained within 1 week Cereals Fish and meat Fish sauce Spices Coconut Coconut milk flesh Total 500 311 1 1 25 12 850 C. Foods into which movement is relatively slow and maximum concentration is attained within 2 weeks Root vegetables Beverage Sugar and vegetable oils Total 1 . 80 5 95 180 Components of diet and amounts consumed adapted from "Federation of Malaya Nutrition Survey", Report Interdepartmental Committee for Nutrition for National Defense, 1904, 365 pp. (Modified In consultation with Vietnamese students at Louisiana State University.) 62 �TABLK 6.—Calculation of upper limits for daily dose of %,4-D and S,4,G-T combined when all food is fully exposed to one aerial application at 26 Ibs/A.1 [Maximum possible contamination, mg/kg/day] Food Group Group A Group C Total 1 gm/porson/ day Immediate 470 30 12 22 30 34 850 180 After 1 week After 2 weeks 7 13 3 23 Sec Table 5. The possibility that any of these assumptions might approach reality is probably nil. Many crops that are treated directly at such high rates show severe damage within a few days and would not bo harvested. Translocation or penetration of residues into coconut meat and milk and banana pulp would take some time to occur, if at all, and would probably be at levels much lower than amounts deposited on foilago. The amount of residues of these chemicals that would penetrate into kernels of mature rice; through palca and lemma is probably a very small percentage, if any, of the dose applied. There docs not appear to be information on these points, however. Probably the greatest potential hazard from contaminated food would be from ingesting leafy green vegetables, other vegetables, and fruits. Much of the drinking water in the villages of Vietnam is from shallow, open wells and from rainwater collected from the roofs of thatched houses. Direct application of heavy rates of herbicide to those sources could result in the ingestion of substantial amounts of the chemicals in rainwater collected from roofs of houses. Assuming that about 270 mg of herbicide is applied per sq. ft. of surface, that water supplies are collected from rain falling on a roof having a total area of 200 sq. ft., and that all of the herbicide is washed off immediately after application and collected in containers holding 200 liters, a 60 kg person drinking 31. of water could get about 10 mg/kg/day. No information is available on the amounts of those chemicals that can be washed off a thatched roof by rainfall. However, data on rates of dissipation of 2,4-D and 2,4,5-T from dead litter material in pastures show rates of disappearance slower than for green tissues (18). Thus, it appears reasonable to expect considerably less than 100 percent of the amount applied to be washed off a thatch roof treated with 2,4-D and 2,4,5-T. Even if it were all washed off, it appears to be unreasonable to expect it all to be captured in vessels having a combined capacity of only 200 liters. Therefore, any reasonable assumption would be that a person getting drinking water from such a source contaminated at the maximum rate possible would got much less than 10 mg/kg/day. 63 �Drinking water from a shallow well contaminated at the maximum rate expected from a 26 Ib/acre application, assuming a depth of 4 feet for water in the well, would amount to loss than 0.5 mg/kg/day, and thus would pose no hazard. Other possible routes of entry into humans from accidental direct application to non-target areas would be by inhalation and penetration through the skin. There is inadequate information available on these points to form any concept of the potential hazard of residues from these sources. Way (.77) has suggested that there is little hazard of transport across the skin barrier. However, those materials are fat soluble which might encourage their percutaneous absorption. At least one study of the acute toxicity of the defoliant, Purple, (esters of 2,4-D and 2,4,5-T) suggested that skin absorption of the animals tested occurred but was perhaps 10-20 times slower than absorption from the GI tract (10). In the extreme situation of a nude, pregnant female, prone beneath an area of spraying of the defoliant, Orange, the maximum impingement of 20.2 nag/kg of 2,4,5-T on her skin might be expected. This should probably be viewed as equivalent to 2.0 mg/kg of an oral dose. REFERENCES (1) AUDUS, L. J. Microbiological breakdown of herbicides in soils. In: Herbicides and the soil. Woodford, E. II., and Sagar, G. R. (Eds.) 1960. («) BATE, J. II., BOVKY, R. W., and SMITH, J. D. Weed Science 17:567, 1969. (3) BBOWN, E. and NISIIIOKA, Y. A. Pesticides Monit. J. 1:38, 1967. (4) COBNELIUSSICN; P. E. Pesticides Monit. J. 0:140, 1969. (ff) DUGGAN, R. E., and LIPSCOMB, G. 0. Pesticides Monit. J. 2:153, 1969. (ff) EHNB, KUET. Acta vet. scand. 7:240, 1966. (7) EBNJ.;, KUET. Acta vet. scand. 7:264, 1966. (8) HOUBU, W. B., GOODSON, L. II., GAUBKBBY, II. M., and DOCKTUB, K. W., Assessment of ecological effects of extensive or repeated use of herbicides. Midwest Research Institute. Project No. 3103-B, December 1967. (9) IIuGHKS, J. S. and DAVIS, J. T., Weeds 11:50, 1963. (10) MC-NAMAEA, B. P. Unpublished observations. (11) MARIGOLD, DOUGLAS B. and SCIIULZK, JEAN A. Pesticides Monit. J. 3:124, 1969. (15) MOETON, II. L., ROBINSON, E. D., and MUYUB, R. E.,.Weeds M:268, 1967. (18) NOEEIS, LOGAN A. Degradation of several herbicides in red alder forest floor material. In: Research Progress Rcpart Western Society of Weed Science, pp. 21, 1969. (14) PALMKE, J. S., and RADKLKFF, R. D. The toxicity of some organic herbicides to cattle, sheep, and chickens. ARS, USDA Production Research Report No. 106, 1969. (IB) TAEEANT, R. F., and NOEKIS, L. A. Residues of herbicides and dicscl oil carriers in forest water. Proc. Symposium on Herbicides in Vegetation Management (Oregon State University) p. 81, 1967. (16) TSCIIIBLKY, F. S. Response of tropical and subtropical woody plants to chemical treatments. ARS, USDA Research Report No. CR-13-67, 1968. (IT) WAY, J. G. Residue Rev. 00:37, 1969. 64 �SOME ECOLOGICAL EFFECTS Summary Elimination of typos of vegetation on which mammals, birds, fish, and insects and other species depend, can severely reduce or eliminate them from the treated habitat. However, altering the vegetation makeup may also benefit certain typos of wildlife. The elimination of water hyacinth from some water bodies, for example, has proved a necessity for the survival of sport fishery programs. 2,4,5-T has been found to affect non-target organisms in a number of ways: 1. Although chickens, quail and mallard ducks appear to be relatively resistant to 2,4,5-T, the herbicide has boon reported to reduce egg production in domestic chickens. 2. Some formulations of 2,4,5-T, such as certain esters, have boon found to bo quite toxic to fish and oysters. 3. The hydrocyanic acid content of sudan grass was found to increase 70 percent following treatment with 2,4,5-T. Nitrate levels in certain plants may increase up to 36 percent following treatment with 2,4,5-T, making thorn more toxic to mammals. Increasing the toxicity of plants to wildlife might have important effects in nature. 5. 2,4,5-T may cause some species of microorganisms to decrease in number while having no effect upon other species. In soil, 2,4,5-T has been found to largely disappear in about throe months. 2,4,5-T has been found to influence non-target organisms both directly and indirectly through habitat changes. The impact of 2,4,5-T on the principal classes of non-target organisms is presented in the following sections. Mammals Roe and Hymas (12) presented data to indicate that the acute oral toxicity LD60 of 2,4,5-T to various species of mammals was about 500 mg/kg. 2,4,5-T has some repellent action. When cottontail rabbits (Sylvilaghs floridarMs) were given a choice of cither 2,4,5-T treated vegetation or untreated, the rabbits consumed almost none of the treated vegetation. (14) 65 �Applying 2,4,5-T or 2,4,5-T in combination with 2,4-D at recommended dosages for brush control in Michigan, resulted in killing the oak type vegetation and released the pine and encouraged a dense ground cover of grasses and other herbs, taller berry producing shurbs, and tree sprouts. (7) The low growing food and cover wore ideal for door, rabbits, grouse, and other forest animals. Chemical brush control was carried out in power-lino right-of-way with 2,4-D and 2,4,5-T applications. Woody brush was practically eliminated. White-tail deer (Odocoileus virginianus) have used both the treated and untreated areas and their use of both areas increased during the four years of investigation. (2) The door made less use of the treated areas during the winter months because there was loss food available. The door fed most heavily in the treated areas in the spring and early summer on various grasses and herbs. Deer also bedded down in the treated areas in patches of sodgo and grass. Numbers of cottontail rabbits were found to increase in the treated areas because of improved food and cover. Birds Fifty percent mortality in birds occurred for the following doses (2,4,5-T fed in the daily diet for loss than 10 days): 5,000 ppm for young bobwhito quail (Golinus virginianus); 5,000 ppm for young mallard ducks (Anas platyrhynchos). (4) Approximate LD..,0's based on estimated food consumption, were: 9,000 mg/kg for the bobwhitc; 21,000 mg/kg for the mallard. The use of 2,4,5-T and 2,4-D for brush control under power linos improved the environment for ruffed grouse (Bonasa umbellus) (2). The grouse wore found on the edges within 150-200 foot of the rightof-way rather than on the right-of-way itself. This emphasized the importance of the right-of-way as a creator of edge effects. Wild turkeys (Meleagris gallopavo) were also observed to make effective use of the rights-of-way treated areas. The young turkeys were attracted to the openings for feeding on various insects which wore more abundant on the grassy right-of-way than within the wooded areas. Chickens were exposed daily for 14 days to grass treated with 2,4,5-T (15 percent active agent) at % oz/gal of water and 2-K oz/gal. (5) The low 2,4,5-T treatment led to a 9 percent reduction in egg yield and the higher dosage to an 18 percent reduction but there was no change in the fertility or hatchability of the eggs. The exposed chickens also lost some weight. Fish The 24-hour LC60* for rainbow trout (Salmo gairdnerii) exposed to 2,4,5-T was 12 ppm; however, Bohmont (1) reported a 48-hour LC80 *LCw, median lethal concentration of a toxicant which kills 80 percent of the test organisms. 66 �for rainbow trout at 1.3 ppm. Bolimont also calculated the 48-hour LC50 for bluogills (Lepomis macrochirus) to bo 0.50 ppm. Young silver salmon (Oncorhynchus kisutch) exposed to a combination of 2,4,5-T and 2,4-D (about 10 percent of each chemical in the formulation) at concentrations of 50 ppm or more were observed to be "immediately distressed and would snap their jaws, dart about the aquarium, and leap out of the water before loss of equilibrium and death." (8) Mullet (Mugil cepiialus) exposed to 50 ppm of 2,4,5-T for 48 hours exhibited no noticeable effects. (3) Table I gives 24- and 48-hour LC^'s of bluogill sunh'sh to various 2,4,5-T formulation. (9) The esters appeared to bo most toxic, probably due to better solubility. No attempt was made by Hughes and Davis to explain the wide variation in results obtained from different batches of the same formulation. TABLE 1.—The LCno of bluegill sunfish to S,4,B-T formulations. (9) 24-hour Dimethylamino Isooctyl ester* Isooctyl ester* Isooctyl ester* Propylcne glycol butyl ethyl ester Butoxycthanol ester : __ -._ 144 31 28 10.4 17 1.4 48-hour 144 31 26 10.4 17 1.4 •Different batches of the same formulation. Molluscs The exposure of oysters (Crassostrea virgmica) to 2.0 ppm ol 2,4,5-T acid for 96 hours had no effect on shell growth. (3) Invertebrates The minimum lethal dosages (ppm) which produced a kill exceeding 25 percent with 2,4,5-T are listed for the following fish food organisms: Daphnia 1.5; Emypris 0.5; Ilyallella 0.7; Palaemonetes 1.2; Amphiagrion 7.5; Pachydiplax and Tramea 8.0; and Chironomus 6.0. (16) The exposure of brown shrimp (Penaeus aztecus) to 1.0 ppm of 2,4,5T for 48 hours had no noticeable effects. (3) Plants Swanson and Shaw (15) demonstrated that the hydrocyanic acid content of sudan grass was increased by 70 percent in pllts treated with 1 Ib/acrc of 2,4,5-T. When 9 species of weeds wen; treated with sublcthal dosages (0.25 Ib/acre of 2,4,5-T, the nitrate content of the plants decreased from 5 to 32 percent in 4 species but increased from 3 to 36 percent 67 �in the other species. (6) The 36 percent increase occurred in Impatiens biflora. The exposure of phytoplanktoii to 1.0 ppm of 2,4,5-T for 4 hours c.aused no decrease in growth. (8) Microorganisms Magoo and Colmer (11) reported that 2,4,5-T at 1,500 to 2,000 ppm produced inhibition of respiration to Azotobacter however, 2,4,5T was found not to affect Streptomyces at 2 and 50 Ib/acre. Persistence 2,4,5-T applied at a rate of % to 3 Ib/acre was found to persist for 2 to 5 weeks with little or no leaching, under summertime conditions in a temperate climate and moist loam soil. (10) Shoots and Harris (IS), however, reported that 2,4,5-T generally persisted for about 3 months under moist soil conditions. REFERENCES (1) (8) (3) (4) (5) (6) (7) (8) (9) (10) (11) (IS) (15) (14) (16) (16) BOHMONT, B. L., Proc., 20th Western Weed Control Conf., 21:25, 1967. BEAMBLK, W. C. and BYRNES, W. R., Pa. Game News 39:17, 1958. BTJTLEK, P. A., U.S. Dcp. Interior, Fish Wildlife Serv. Circ. .707:11, 1963. DEWITT, J. B., STICKEL, W. II., and SPRINGER, P. F., Wildlife studies, Patuxent Wildlife Research Center 1961-62. In Pesticide wildlife studies. U.S. Fish Wildlife Serv. Circ. 167:74, 1963. DOBSON, N., J. Ministry of Agriculture (Britain), 110:415, 1954. FRANK, P. A. and GHIGSBY, B. II., Weeds, 5:206, 1957. GYSEL, L. W., Down to Earth 2, 1957. HOLLAND, G. A., LASATER, J. E., NEUMANN, E. D., and W. E. ELDRIDGE. Toxic effects of organic and inorganic pollutants on young salmon and trout. Wash. Dcpt. Fish. Res. Bull., 5, 1960. HUGHES, J. S. and DAVIS, J. T., Weeds 11:50, 1963. KLINGMAN, T. C., Weed control as a science. John Wiley and Sons, Inc., New York, 1961. MAGEE, L. A. and COLMER, A. R., Appl. Microbiol. 3:288, 1955. ROWE, V. K. and HYMAS, T. A., Amer. J. of Vet. Res. 15:622, 1954. SHEETS, D. J. and HARRIS, C. I., Herbicide residues in soils and their vital toxicities to crops grown in rotations, pp. 119-140 from Residue Reviews, 11, F. A. Gunther (Editor), Springer-Verlag, New York, Inc., 1965. SPRINGER, P. F., North Carolina Pesticide Manual, 1957. SWANSON, C. R. and SHAW, W. C., Agron. J. 40:418, 1954. ZISCHKALE, M., Field & Lab., #0:18, 1952. 68 U.S. GOVERNMENT PR � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Alvin L. Young Collection on Agent Orange Description An account of the resource <p style="margin-top: -1em; line-height: 1.2em;">The Alvin L. Young Collection on Agent Orange comprises 120 linear feet and spans the late 1800s to 2005; however, the bulk of the coverage is from the 1960s to the 1980s and there are many undated items. The collection was donated to Special Collections of the National Agricultural Library in 1985 by Dr. Alvin L. Young (1942- ). Dr. Young developed the collection as he conducted extensive research on the military defoliant Agent Orange. The collection is in good condition and includes letters, memoranda, books, reports, press releases, journal and newspaper clippings, field logs and notebooks, newsletters, maps, booklets and pamphlets, photographs, memorabilia, and audiotapes of an interview with Dr. Young.</p> <p>For more about this collection, <a href="/exhibits/speccoll/exhibits/show/alvin-l--young-collection-on-a">view the Agent Orange Exhibit.</a></p> Text A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text. Box The box containing the original item. 039 Folder The folder containing the original item. 0882 Series The series number of the original item. Series III Subseries I Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Creator An entity primarily responsible for making the resource MacLeod, Colin M. et. al. Description An account of the resource <strong>Corporate Author: </strong>Panel on Herbicides of the President's Science Advisory Committee, Executive Office of the President, Office of Science and Technology Date A point or period of time associated with an event in the lifecycle of the resource March 2 1971 Title A name given to the resource Report on 2,4,5-T: A Report of the Panel on Herbicides of the President's Science Advisory Committee Subject The topic of the resource herbicide properties herbicide toxicology ecological impact ao_seriesIII https://www.nal.usda.gov/exhibits/speccoll/files/original/2d2536c9707f78bc589bc392f8a30893.pdf 043e765d00de2bfdab808716842e163f PDF Text Text Item ID Number 00884 Author MacMahon, Brian Corporate Author Subcommittee on Agent Orange Review, Committee on Report/Article Title The Effects of Exposure to Agent Orange on Ground Troops in Vietnam: A Report of a Subcommittee Appointed to Review a Protocol (dated January 22, 1982) Prepared by the University of California, Los Angeles, at the Request of the Veterans Administration Journal/Book Title Year 1982 Month/Day October Color Number of Images DOSOrlptOR NOtOS n 27 Alvin L - Young filed this item under the category "Human Exposure to Phenoxy Herbicides and TCDD"; "The work presented in this report was supported by the Veterans Administration, under Contract No. V101(93)P887" Friday, March 16, 2001 Page 884 of 967 �u. The Effects of Exposure to Agent Orange on Ground Troops in Vietnam A report of a subcommittee appointed to review a protocol (dated January 22, 1982) prepared by the University of California, Los Angeles, at the request of the Veterans Administration for The Committee on Epidemiology and Veterans Follow-up Studies Commission on Life Sciences National Research Council October 1982 �NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the Councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Research Council was established by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and of advising the federal government. The Council operates in accordance with general policies determined by the Academy under the authority of its congressional charter of 1863, which establishes the Academy as a private, nonprofit, self-governing membership corporation. The Council has become the principle operating agency of both the National Academy of Sciences and the National Academy of Engineering in the conduct of their services to the government, the public, and the scientific and engineering communities. It is administered jointly by both Academies and the Institute of Medicine. The National Academy of Engineering and the Institute of Medicine were established in 1964 and 1970, respectively, under the charter of the National Academy of Sciences. The work presented in this report was supported by the Veterans Administration, under Contract No. V101(93)P-887. Available from Medical Follow-up Agency National Research Council 2101 Constitution Avenue, N.W. Washington, D. C. 20418 �COMMITTEE ON EPIDEMIOLOGY AND VETERANS FOLLOW-UP STUDIES BRIAN MacMAHON (Chairman), Harvard School of Public Health RANSOM J. ARTHUR, School of Medicine, University of Oregon MICHAEL E. DeBAKEY, Baylor College of Medicine JOHN R. DURANT, Cancer Center, University of Alabama GARY D. FRIEDMAN, Kaiser-Permanente Medical Care Program BARBARA S. HULKA, Department of Epidemiology, University of North Carolina ALLYN W. KIMBALL, Johns Hopkins University School of Hygiene and Public Health LEONARD T. KURLAND, Medical Statistics and Epidemiology, Mayo Clinic DOROTHY P. RICE, National Center for Health Statistics SEYMOUR JABLON, Staff Officer SUBCOMMITTEE ON AGENT ORANGE REVIEW George C. Becking Health Protection Branch Department of National Health and Welfare Ottawa, Canada Gary Friedman Medical Methods Research Department Kaiser-Permanente Medical Care Program Oakland, California Allyn W. Kimball Department of Biostatistics Johns Hopkins University, School of Hygiene and Public Health Baltimore, Maryland Leonard Kurland Department of Epidemiology and Medical Statistics Mayo Clinic Rochester, Minnesota Brian MacMahon, Chairman Department of Epidemiology Harvard University, School of Public Health Boston, Massachusetts Staff: C. Dennis Robinette Medical Follow-up Agency National Academy of Sciences - National Research Council Washington, D. C. �Summary of Recommendations 1. If any attempt is to be made to study health effects of "the Vietnam experience" more broadly than the exposure to Agent Orange, it should be made independently of the Agent Orange study. 2. Before a decision is made to proceed with the main Agent Orange study, there should be a formal review to determine the meaningfulness of the classification of study participants by exposure status and the views of interested parties should be ascertained and recorded, 3. A fully satisfactory method of selection of participants has not been described to the Subcommittee. This matter requires much further investigation and evaluation. 4. If an individual exposure index is calculated for each possible study subject, rather than two (high and low exposure) cohorts there should be three (high, intermediate, and low exposure). 5. The cohorts should be selected as several — say four — independent subsamples. 6. (a) Marines should be included if they can be identified in sufficient numbers for separate analysis and if they can be included in equal proportions to the total numbers in each cohort. (b) Air Force personnel should not be included. (c) Officers should not be included. �-2(d) Enlisted men with multiple tours of duty in Vietnam should not be included. (e) Every effort should be made to include the crews and servicemen of Army-based helicopters used for spraying, as well as suitable non-exposed individuals from other helicopter operations. 7. Greater emphasis should be placed on the study of mortality in the selected cohorts up to the present and into the future- 8. (a) The current questionnaire and clinical protocols require considerable revision. They should take advantage of the expertise and experience expended on the design and the experience gained in the implementation of the protocols for the Ranch Hand study. (b) The pilot study for the clinical investigation should not be initiated until findings from the Ranch Hand study are available. The Subcommittee was informed that data collection for the Ranch Hand study would be completed by September (c) 1982. Findings from mortality analyses should also be used to modify the clinical protocols, if appropriate. (d) The questionnaire needs particular attention. (e) The protocols should be more focused toward known effects of exposure of humans or other species to dioxins. (f) 9. A tiered approach to clinical testing is recommended. More attention should be paid to issues of quality control in the clinical examinations. The pilot study should include at least three examination sites. 10. The payment of incentives to participants seems reasonable and desirable. �-3- 11. Responsibility for the main study should rest with an academic-based coordinating center strong in biostatistics and epidemiology, with experience in multi-center collaborative studies and answering to a Steering Committee. The Steering Committee would include representatives of the participating units, which might be in academic or non-academic settings. 12. The present questionnaire and clinical protocol, and any subsequent drafts, should be made available to interested parties. 13. There should be representation of the socio-behavioral sciences in the planning and implementation of the study. 14. If this program goes forward, the funding required should not be diverted from the regular medical research budget of the VA. �-4- Intreduction The Subcommittee had as its assigned charge to review and comment on the protocol prepared by the University of California, Los Angeles (UCLA), (Principal Investigator Gary H. Spivey, M.D., MPH) and, if appropriate, to make suggestions which might strengthen the protocol and improve the effectiveness and efficiency of the final study. The Subcommittee found its approach to this charge compli- cated by a number of circumstances; (1) That some study must be done has been mandated by Congress, and it has been further mandated that the study should be "epidemiolbgical" in nature and have as its goal the detection of "any long-term health effects in humans" (emphasis added) attributable to "exposure to the phenoxy herbicides (including the herbicide known as Agent Orange)..." (Public Law 97-72, Nov. 3, 1981 95 'STAT 1061). The range of research designs that might be considered to approach the overall objective is therefore limited by the congressional mandate. (2) The UCLA protocol already has been reviewed, modified, and reviewed again by at least two committees or panels (of the White House and of the Office of Technology Assessment), both of which had representation of scientific disciplines considerably broader than this Subcommittee, as well as by veterans' organizations. The reports of these review panels are available to the Subcommittee. (3) Notwithstanding the UCLA protocol, the previous reviews of it, and the existence of this Subcommittee, the Veterans Administration (VA), with support from the Department of �-5Defense (DOD) in the selection of cohorts, is well along in the planning of a pilot study of Vietnam veterans directed to this issue, with a target date for initiation of January 1, 1983. The method of selection of the cohorts for the pilot study being used by DOD differs in important ways from that proposed in the UCLA protocol — a change that is defended principally in terms of economy — but it is not clear to the Subcommittee that the scientific implications of the change have been thoroughly explored. In these circumstances, the Subcommittee considers that it would be of little service to prepare a detailed review of the UCLA document as written — a document that is already worn around the edges insofar as it can be regarded as a blueprint for any likely action — or to add its own voice to those who previously have reviewed the protocol in detail and whose recommendations are on record. Rather, the Subcommittee proposes to present its views (some solicited and some not) on certain broad issues which the VA and other planners of this study must face in the next few months. First, the Subcommittee agrees with the UCLA investigators and other reviewers that, given the objectives, the most appropriate form of study design has been selected. It is proposed to identify cohorts (groups) of ground forces characterized as to relative level (or levels) of exposure to phenoxy herbicides during the Vietnam experience, to follow these cohorts with respect to mortality subsequent to their Vietnam service, and to measure many parameters of current health status. These parameters will be compared between the different exposure cohorts. This form of study is commonly �-6called a retrospective cohort or retrospective follow-up study and is appropriate when (a) the exposure of interest occurred in the past and is documentable and (b) a number of different possible health, or ill-health, outcomes are to be investigated. The most frequent alternative approach to the study of suspected causal associations between environment and health is to select a group of individuals manifesting a disease that is hypothesized to relate to the exposure (the cases) and a group of individuals without that particular manifestation (the controls) and to compare the cases and controls with respect to frequency or intensity of past exposure. The range of ill effects alleged to result from exposure to Agent Orange (AO) is so broad as to make the case-control approach unfeasible if any substantial proportion of them is to be addressed. This is not to say, however, that some case-control studies may not be feasible and desirable; indeed, such studies may well produce more information — dollars — and for fewer than the all-encompassing cohort study. For example, there is evidence from non-military exposures that risk of soft-tissue sarcomas may be increased following fairly heavy exposures to phenoxy herbicides. A case-control study of soft-tissue sarcomas within the veterans population would almost certainly be the quickest and most economical way to determine whether these malignancies are associated with exposure to herbicides in Vietnam. Such a study would not, however, address the many other outcomes of herbicide exposure that can be hypothesized and which have been suggested. Nevertheless, the Subcommittee will address principally the questions which have been raised with it and which the Subcommittee �— 7— had regarding the retrospective cohort study, since this is the subject of the UCLA protocol and current VA plans. The following issues are not in any discerned order of importance or priority. 1. Addition of a study of "the Vietnam experience" In permissive (i.e., not mandatory) language, the 1981 Public Law states that "the Administrator (of Veterans' Affairs) may expand the scope of the study to include an evaluation of any long-term health effects in humans of such service (in Vietnam) that may result from other factors involved in such service, including exposure to other herbicides, chemicals, medications, or environmental hazards or conditions." This language has resolved into a debate as to whether, by adding a third cohort of servicemen without experience in Vietnam, the intent of this clause may be met by comparing the non-Vietnam cohort with the cohorts assembled for the AO study. Of the latter, the UCLA protocol and the VA currently envisage two — one with high and one with low exposure to AO. components of "the Vietnam experience" — The quite apart from the physical and psychological impacts of participation in combat — are multiple. A partial list includes exposure to insect repellents, insecticides, water purification chemicals, antimalarial drugs, petroleum distillates including napalm, weapons residues, chemical weapons, beverage alcohol, illegal narcotics, liquid hexachlorophene soaps, immunizations, food contaminants, dioxin-containing pentachorophenol (for wood preservation) and a variety of viral, bacterial, fungal and parasitic diseases and their therapies. The Subcommittee believes that the complexity of this "Vietnam experience" is such that it will likely never be possible to study �-8- it in any meaningful way — that is, a way that would permit linkage of specific health outcomes to specific components of the experience. Nor is it clear that a suitable comparison group with which to compare the health of the Vietnam veterans has been (or can be) identified. However, if it is decided to make an attempt to study the effects of the total Vietnam experience the Subcommittee strongly urges that it not be done through the over-simple expedient of adding a non-Vietnam cohort to the AO study. The Subcommittee's reasons for this view are as follows: (a) The AO study is itself very complex. Yet its complexity would be dwarfed by that of an attempt to study the Vietnam experience overall. There is a serious danger that the addition of the "Vietnam experience" component would jeopardize the already insecure scientific base on which the AO study rests. (b) For a study of "the Vietnam experience", contrasting the experience of military ground forces in Vietnam with that of those in some other theater, the sample of Vietnam veterans should be selected in a different fashion from that required for the AO study. Two Vietnam cohorts representing the extremes of high and low exposure to AO are almost certainly not representative of all ground forces that saw service in Vietnam. (c) The Subcommittee shall address later the desirability of focusing and shortening the medical history and clinical data collection instruments. More focused instruments — which would be highly desirable for either study — will * be different according to whether .one is looking for suspected effects of AO or of the total Vietnam experience. �-9- For these reasons the Subcommittee recommends that the desirability and design of a study of the long-term effects of the total Vietnam experience be considered independently from the planning for the AO study. 2. Feasibility of the retrospective cohort study For several years the retrospective cohort study was widely regarded as unfeasible — principally because of the difficulty of assembling from existing records valid information on the exposure of individuals to AO and other herbicides. On the basis of prelimi- nary work on the part of DOD, this view has now changed. Those responsible for the DOD record review now state that, not only will it be possible to identify individuals with presumptively high levels of exposure to AO/ but that it should be possible to select a comparison cohort of low-exposure individuals from military units with combat and jungle experience similar to that of the highexposure cohort. Consequently, the VA is planning to proceed with clinical examinations for a pilot study beginning January 1, 1983. As noted above, a retrospective cohort design is an appropriate one when the exposure of interest occurred in the past and is documentable. Everybody understands and agrees that the document- ability of exposure, or lack of exposure, is a sine qua non for this study. If the compared cohorts are not1 markedly dissimilar with respect to true cumulative exposure levels the study is unlikely either to reveal health effects that do exist or to satisfy the public that a valid search for such effects has been undertaken. The Subcommittee indeed questions the wisdom of proceeding with the pilot study until this issue is settled. So far as the Subcommittee �-10- is aware, the DOD record review to date has concentrated on the identification of high-exposure individuals. The method depends on identifying individuals who receive a high exposure during a given time period (approximately one year), and presumably could be used similarly to identify individuals receiving low (or no known) exposure during comparable periods. However, the validity of the procedure remains essentially unevaluated. A decision to proceed with the pilot clinical examinations may be justified on the grounds that the feasibility of this phase of the study is equally as critical to the main study as is the estimation of exposure and that a matter of such national priority and urgency warrants proceeding with both assessments simultaneously even though a failure in either one will argue against proceeding with the main study. There are certainly important issues of feasi- bility to be assessed for the clinical component of the study. For example, although the response rate in the Air Force's study of its "Ranch Hand" veterans who sprayed herbicide from fixed-wing aircraft has been extraordinarily good (of the order of 94 percent), this is a special group with a high esprit de corps ? such a response rate cannot automatically be assumed for a more broadly selected group of veterans. A high participation rate in the clinical program is essential if it is to produce reliable results. Vigorous efforts must be made to ensure the cooperation of at least 75-80 percent of those invited to participate. If the participation rate falls short of this target or if the rates in the high and low exposure cohorts differ by more than 10 percent, considerations should be given to abandoning the clinical examination component of the program. �-11In addition, it must be kept in mind that a successful completion of the clinical pilot study is not alone a sufficient basis on which to proceed with the main study — the issue of adequate separation of the cohorts by exposure level must also be addressed. Unfortunately, there appear to be no objective criteria on which to validate this separation. At a minimum, the criteria used to define the cohorts must be sufficient to convince those involved — including the veterans' organizations — meaningful in terms of exposure. that the separation is Documented assurance that the meaningfulness of the separation has been accepted by interested parties should be a prerequisite to a decision to proceed with the main study. One suggestion for evaluating the validity, or at least replicability, of the exposure assessment has been that exposure measures as determined for the study from records (see Section 3, below) be compared with self-reported exposures to be elicited during the clinical examinations and questionnaires. While the possibility of error, and indeed bias, in self-reporting is evident, such a comparison would be an important part of the analysis of the pilot study data. An intermediate exposure cohort (see section 4) might be particularly valuable in this connection. 3. Assessment of exposures of individual veterans The method of identifying veterans with relatively high levels of exposure to AO currently being used by DOD differs importantly from that recommended in the UCLA protocol. that an exposure index — The protocol recommends a cumulative measure of the product of presumed level of exposure and time served at that level — be �-12- computed for essentially all Vietnam veterans, and that the high-exposure and low-exposure cohorts be selected from individuals at the top and bottom of a ranking by this index. The DOD procedure depends on first identifying military units (generally Companies) with probability of high exposure and then assembling the histories of individuals in these units. Presumably, a comparable procedure will be used to identify the low-exposure cohort. Officials of DOD estimate the cost of record review necessary to carry out the UCLA plan as $27-40 million, and of their own procedure as $3 million. The saving is clearly of consequence. However, the DOD procedure imposes certain constraints on the selection procedure, the consequences of which have not been fully explored. For example, an individual's cumulative exposure is estimated over a twelve-month • period beginning with an arbitrary date (July 1). Consequently, individuals who began service in Vietnam in that particular month are more likely to be selected into the high-exposure cohort. It is not clear whether such temporal constraints are also intended to apply to the low-exposure cohort or, if it is, how this can be accomplished. There are probably other selective factors that a more detailed review than the Subcommittee has been able to undertake would identify. Even if such factors are not specifically identified it seems ill-advised to use a selection procedure that cannot be followed in an exactly comparable way for high and low exposure groups. Since the protocol for the DOD selection procedure was not available in written form for the Subcommittee's review and because the time available for this review was limited, the Subcommittee cannot judge how comparable the selection procedure for the high and �-13low exposure cohorts will be. The Subcommittee notes, however, that the clinical examinations for this study are estimated to cost over $10 million, and may be much more. It would be false economy to choose, on the basis of its cost, a cohort selection procedure that jeopardizes the validity — the study findings. or even the appearance of validity — of This issue requires much further investigation before the final method of cohort selection is decided. It may be that an intermediate procedure can be identified which combines the advantages of the UCLA proposal with the (relative) economy of the DOD procedure. It does appear to the Subcommittee that the UCLA proposal is unnecessarily ambitious, and it sees no problem in beginning the selection process with presumed high (or low) exposure military units. Further, there are advantages to focusing on particular time periods when (a) spraying was heaviest and (b) the level of contamination of the herbicides with dioxin was highest. At a minimum, though, the procedure should be such that: for each man entered into the study his exposure must be assessed throughout his tour of service in Vietnam for each man entered, an exposure index, of the form proposed by UCLA, should be calculated at some point, individuals must be selected in random subsamples after the high and low exposure units have been identified (see point 5). 4 * The number of cohorts to be studied It is currently proposed — the VA pilot study plans — both in the UCLA protocol and in to select only two Vietnam cohorts, one with the highest ascertainable exposures and one with the lowest.. �-14- Since the assessment of exposure is so critical to the interpretation of the study results, the Subcommittee suggests that the design provide an opportunity to look for dose-response effects. The Subcommittee therefore suggests that three exposure groups be selected covering the entire range of exposure assessments — low, medium, and high. By having the entire range of exposures represented, one would be able to utilise the exposure index of each subject in more efficient regression-type analyses, if they should be indicated, as well as looking for trends among the three exposure groups. This recommendation assumes that, as proposed by the UCLA protocol, an individual "exposure index" will be available and can be used for the definition of the three exposure groups. If, on the other hand, exposure indices are not calculated for each proposed member of a study cohort, then only presumptively high and low exposure cohorts will be identifiable. 5 * Selection of the cohorts in sub-samples The protocol's discussions of sample size are based on assumptions that the distribution of variables to be examined is binomial. Statistical estimates of power and/or sample size requirements in a study with so many outcomes to be evaluated actually have little sway in determining the actual size of the cohorts to be examined. However, some knowledge of the nature of the underlying distributions is necessary for the application and interpretation of significance tests — the distributions cannot arbitrarily be assumed to be binomial. The Subcommittee suggests that the cohorts be selected as several independent samples — say four. This would permit an assessment of the validity of the binomial assumption and provide a basis for a proper statistical analysis. �-15- Further, if each of the high and low exposure cohorts are selected as a group of independent subsamples, there will be opportunity to compare the variability within each cohort with the variability between cohorts. This will enable discrimination between effects which result from the exposure to herbicides from other differences which may exist among companies similarly exposed to herbicides but having different exposures to other potentially harmful influences. The selection suggested here could be accomplished by randomly assigning candidate companies to one or another of the subcohorts before examining the individual records. 6. Forces to be included The principal source of subjects for the study will be Army enlisted ground troops. The Subcommittee was asked for opinions regarding inclusion of some other groups. These opinions are as follows: (a) Inclusion of Marines would be desirable if they can be included in sufficient numbers for separate analysis (e.g. 1,000-2,000 in each cohort — this will probably require over-sampling) and if they can be included in each cohort in equal proportions to the total numbers of the cohorts. The latter is essential because of the likelihood of differences between Marines and pther troops in entrance physical and other selective factors. (b) Air Force personnel should not be included since they would unnecessarily complicate the analysis (if account were to be taken of between-service differences) and their principal exposed group (members of the Ranch Hand operation) are the subjects of an independent study now in progress. �-16- (c) Officers, while offering the potential for being a highly exposed group because of multiple tours of service, should not be included since they can probably not be included in sufficient numbers for separate analysis. Further, the fact that many will have had multiple tours of duty in Vietnam complicates the assessment of their exposure and makes it unlikely that they can be included in equal proportions in the high and low exposure cohorts. (d) Similar considerations as those described for officers apply to enlisted men with multiple tours of Vietnam duty. Any attempt to include them would greatly compli- cate the process of assuring equal representation in the several exposure cohorts. Further, the logistics of ascertaining their total exposure over multiple tours of duty becomes particularly complex when, as is proposed by DOD, the selection begins with exposed and not-exposed military units, rather than individuals. (e) An important group to include if they can be identified are the crews and servicemen of Army-based helicopters used for spraying operations. They appear to have been among the most heavily exposed groups of all. Comparable non-exposed (or at least low exposure) groups could be assembled from the crews and servicemen of helicopter gun-ships and other helicopter operations. 7. Examination of mortality data The UCLA protocol, and so far as is apparent the current VA plans/ emphasize strongly the information to be obtained at the time �-17of questioning and physical examination of the selected cohorts. Only in correspondence subsequent to submission of the protocol do the UCLA investigators express any concern for the evaluation of mortality in the selected cohorts between the time of Vietnam service and the present. In the Subcommittee's view, the observation of cause-specific mortality in the selected cohorts both up to the present time and even more importantly into the future deserves much greater prominence than it has received. First/ mortality data will provide the most objective and unassailable evidence for the presence or absence of some — though certainly not all — of the possible hazards of exposure. Second, mortality data up to the present may provide a basis on which to sharpen the questionnaires and physical examinations. For example, any excess of mortality from atherosclerotic heart disease among highly exposed individuals would have an important impact on the information to be sought at physical examination. Last, in comparison to the expense of the physical examination program, the mortality data can be assembled at very small cost. 8. Scope of the questionnaire and physical examination The questionnaire and physical examination protocol included with the UCLA proposal are notable for their comprehensiveness. Indeed, they are formidable. While recognizing that this study is essentially a "fishing expedition", the Subcommittee believes that a questionnaire and physical examination protocol that are more focused and selective would lead to more enthusiastic participation and enhance the quality of information obtained. The Subcommittee believes that considerable revision of the current questionnaire and clinical protocol is required and offers the following recommendations: �-18(a) The protocols should be coordinated with those for the Ranch Hand study. The UCLA protocols are said intention- ally to rely heavily on the proposed study of AO exposure among Australian troops in Vietnam. The rationale is to permit comparison of findings and mutual testing of hypotheses arising from either set of data. With the uncertainty regarding the future of the Australian study, it seems more important that the VA protocols be compatible with those of the Ranch Hand study. Further, the protocols for the Ranch Hand study have been carefully designed and tested and — while the VA study may not incorporate all their components — there is much to be learned from them. (b) The pilot study for the VA study should not be implemented until findings from the Ranch Hand study are available. The guidance from that investigation should have a significant impact on the direction, methods and procedures of the UCLA project. Identification of key issues, organiza- tion of data collection including questionnaires and examinations such as special neurological and psychological tests, laboratory tests, etc. Ranch Hand may help identify areas where differences between "exposed" and "non-exposed" are most unlikely, borderline, or more dramatic. On the basis of the variability in the results in these three groups it should be possible to focus and expand on key outcomes and to eliminate some other areas of inquiry. The loss of time involved in waiting for these results should be more than made up through refinements in method and increased focus on key end results. �-19- If a pilot study were undertaken prior to the availability of Ranch Hand results, and any substantial modification of the clinical protocols were subsequently required, the VA might find itself in the position of having to do a second pilot study. It is even possible that, if findings from the Ranch Hand study point to the possibility of a limited number of specific outcomes being associated with AO exposure, the cohort approach could be abandoned and replaced by one or more targeted case-control studies. (c) While not quite so critical as the Ranch Hand morbidity results it is also conceivable, as noted elsewhere, that mortality data will be useful in modifying the clinical protocols. (d) The present questionnaire needs especial attention. It consists of questions about health and non-health characteristics of the veteran and spouse and may be broadly described as covering demographic, lifestyle, and occupational items. Language varies from the vernacular which may be misunderstood in some groups of veterans to esoteric diagnoses which few will understand. Information on infections and parasitic diseases is skimpy and that on trauma and its consequences seems underemphasized. Opportunities should be provided in the pilot study for the participants for open-ended insertions — particularly insertions of chemical, biological, and psychological exposures both in and out of Vietnam for which the participant may volunteer information. The emphasis on diag- noses rather than symptoms is difficult to understand, • �-20since the questions (i.e. the terms) may be often misunderstood. A survey of symptoms present and past might provide more valid results — and trigger in-depth probes to diagnoses regarded as key end points. The neurology questions require further evaluation — the input of a neurologist experienced in this mode of inquiry would be helpful. A comparison of recent and past skills to uncover defects in coordination and equilibrium, sensation, muscle strength, intellect, speech, memory, etc. would be desirable. The format and topics of inquiry about pregnancies appeared better organized and more likely to uncover pregnancy wastage, perinatal death, malformations, mental retardation, etc. in the Ranch Hand forms than in the UCLA questionnaire. for each pregnancy — Specific questions smoking, alcohol, use of drugs known or suspected of being teratogenic, should be determined and documented through medical records when feasible. (e) The protocols should be focused, if possible, on known effects on humans and animals of exposure to phenoxy herbicides contaminated with TCDD. These would include effects on skin, reproductive organs, immune system, peripheral nervous system and liver function (including porphyrin metabolism). (f) To satisfy scientific as well as political needs, the Subcommittee suggests a tiered approach to clinical testing. That is, a core battery of tests to be carried out on each subject with more sophisticated tests carried out on say 10-20 percent of the cohort. For example, �-21liver function (including tests for cholesterol and triglycerides), an imraunotoxicity screen and a complete blood cell workup should be carried out on all subjects. Nerve conduction tests and sperm abnormality tests could be done on 10-20 percent of the cohort or as dictated by the answers from the questionnaires. 9. Quality control in the physical examinations On the critical issue of quality control of data from clinical and laboratory examinations conducted in multiple sites across the nation, the UCLA protocol is silent. The issues will have to be addressed in much greater detail than is possible here. There must be a balance of high, medium, and low exposure cohorts at each examination site and during the course of the examinations. Inter- and intra-site differences will need to be assessed for each clinical characteristic examined and for all laboratory tests that cannot be centralized. The Subcommittee recommends that these issues be begun to be addressed in the pilot study. There should be at least three examination sites in the pilot study so that variability in examination and reporting can be assessed. Further, these sites should not be the "best" or most cooperative sites that can be found under the exigencies of the current time schedule but should be selected so as to be more or less representative of the types of facility that are likely to participate in the main study. �-22- 10. Incentives The Subcommittee was asked for an opinion regarding the use of incentive payments to reimburse participants for time spent in participating in the clinical studies. tial — This time can be substan- approximately four days in the Ranch Hand study — and it seems only reasonable that the participants would expect some compensation for it. The likelihood that an individual participant will benefit medically from his participation is small. It is likely that the incentive offered to the Ranch Hand participants ($100/day) contributes to the very high participation rate, and such an incentive is also likely to increase participation in the VA study. While it is true that the payment of incentives may bias the participation in favor of those who, for a variety of reasons, need the money, such bias will not be a source of real criticism if a participation rate approaching that of the Ranch Hand study is obtained. Even if it is not, the bias should in considerable degree apply similarly to the different exposure cohorts. On balance, the Subcommittee believes that to offer an incentive is an appropriate thing to do. 11. Responsibility for the main study The question has been raised as to whether the VA should itself accept responsibility for coordinating the main study or whether this task should be contracted out. VA hospitals have some of the best clinical and laboratory facilities in the country, and many have considerable experience of participation in multi-site studies. The desirability of using these resources should be assessed when the perceptions and attitudes of veterans towards examinations in VA facilities have been determined (see point 13). �-23- However, the Subcommittee believes that a stronger central scientific team to coordinate the whole effort can be assembled outside the VA than within it. Location of ultimate responsibility outside the VA would have the additional political advantage of making it quite apparent that the VA, on its own or under pressure from any of its many constituents, could not in any way influence or conceal the findings. The Medical Follow-up Agency of the National Research Council would, for several reasons, not be an appropriate organization to coordinate this study. The Subcommittee recommends that the study be conducted by some university group that is strong in epidemiology and biostatistics and has experience in national collaborative studies. The model followed in many cooperative clinical trials, in which a Coordinating Center which conducts the day-to-day business of the study and is responsible to a Steering Committee representing each of the participating clinical units, would seem to be a suitable one here. If this option is chosen, the Coordinating Center should be selected first and should have input into the selection of the participating clinical centers. 12. Confidentiality of the questionnaire and clinical protocol » The VA has gone to considerable lengths to maintain the confit dentiality of the proposed questionnaire and clinical protocol. The rationale has been that if such material became public there would be opportunities for participants to be coached into responses that some groups wish to see. The Subcommittee believes that (a) the opportunity for such coaching exists whether or not the specific details of the questionnaire are known, (b) there is no evidence �-24- that such coaching is actually intended by any group, (c) as other reviewers have pointed out, the important thing from the point of view of questionnaire validity is to ensure that the respondents are unaware of the exposure cohort to which they are assigned — in which case inaccurate or deliberately false responses should not introduce associations that do not in reality exist, and (d) the policy runs the risk of alienating individual veterans and veterans' organizations whose collaboration will help assure the successful completion of the study. The Subcommittee recommends that copies of the present protocols and of subsequent modifications of them be made available to interested parties. 13. Representation of the socio-behavioral sciences The Subcommittee notes the almost total lack of input from the socio-behavioral sciences in the present protocol. Representation from these fields would strengthen the questionnaire and other aspects of the study design. veterans — In addition, the cooperation of both as organizations and as individuals — to the success of the study. is essential Behavioral scientists should determine how the study is perceived by individual veterans at each step of the protocol. If the study population becomes disenchanted wiih the conduct of the study, the study may fail or its results may fail to convince those who need to be convinced. 14. Financing of the study In providing for this program to go forward, the VA's highly productive medical research program must be protected; funds for the Agent Orange study should be supplied separately and not diverted from the VA medical research funding. � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Alvin L. Young Collection on Agent Orange Description An account of the resource <p style="margin-top: -1em; line-height: 1.2em;">The Alvin L. Young Collection on Agent Orange comprises 120 linear feet and spans the late 1800s to 2005; however, the bulk of the coverage is from the 1960s to the 1980s and there are many undated items. The collection was donated to Special Collections of the National Agricultural Library in 1985 by Dr. Alvin L. Young (1942- ). Dr. Young developed the collection as he conducted extensive research on the military defoliant Agent Orange. The collection is in good condition and includes letters, memoranda, books, reports, press releases, journal and newspaper clippings, field logs and notebooks, newsletters, maps, booklets and pamphlets, photographs, memorabilia, and audiotapes of an interview with Dr. Young.</p> <p>For more about this collection, <a href="/exhibits/speccoll/exhibits/show/alvin-l--young-collection-on-a">view the Agent Orange Exhibit.</a></p> Text A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text. Box The box containing the original item. 039 Folder The folder containing the original item. 0884 Series The series number of the original item. Series III Subseries I Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Creator An entity primarily responsible for making the resource MacMahon, Brian et. al. Description An account of the resource <strong>Corporate Author: </strong>Subcommittee on Agent Orange Review, Committee on Epidemiology and Veterans Follow-Up Studies Date A point or period of time associated with an event in the lifecycle of the resource 1982-10-01 Title A name given to the resource The Effects of Exposure to Agent Orange on Ground Troops in Vietnam: A Report of a Subcommittee Appointed to Review a Protocol (dated January 22, 1982) Prepared by the University of California, Los Angeles, at the Request of the Veterans Administration Subject The topic of the resource study protocol ao_seriesIII Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Alvin L. Young Collection on Agent Orange Description An account of the resource <p style="margin-top: -1em; line-height: 1.2em;">The Alvin L. Young Collection on Agent Orange comprises 120 linear feet and spans the late 1800s to 2005; however, the bulk of the coverage is from the 1960s to the 1980s and there are many undated items. The collection was donated to Special Collections of the National Agricultural Library in 1985 by Dr. Alvin L. Young (1942- ). Dr. Young developed the collection as he conducted extensive research on the military defoliant Agent Orange. The collection is in good condition and includes letters, memoranda, books, reports, press releases, journal and newspaper clippings, field logs and notebooks, newsletters, maps, booklets and pamphlets, photographs, memorabilia, and audiotapes of an interview with Dr. Young.</p> <p>For more about this collection, <a href="/exhibits/speccoll/exhibits/show/alvin-l--young-collection-on-a">view the Agent Orange Exhibit.</a></p> Text A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text. Box The box containing the original item. 028 Folder The folder containing the original item. 0449 Series The series number of the original item. Series III Subseries I Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Creator An entity primarily responsible for making the resource Aliverdiyeva, Sh. S. et. al. Source A related resource from which the described resource is derived Azerbaidzhanskii Meditsinskii Zhurnal (Azerbaidzhan Medical Journal) Date A point or period of time associated with an event in the lifecycle of the resource 1983 Title A name given to the resource Work Conditions and Health State of Workers in the Production of Monochloroacetic ad 2,4-Dichlorophenoxyacetic Acids Subject The topic of the resource human exposure health effects ao_seriesIII