The objective of this study was to characterize the ability of a virgin layer of PETE to serve as a functional barrier to the migration of organic contaminants. Absorption concerns have caused the FDA to question the safety of recycled plastics. They fear contaminants acquired through post-consumer recycling abuses might result in dangerous levels of household chemicals absorbing into plastics and ultimately leaching into foods held in second generation containers.
The FDA has issued guidelines to help resin recyclers determine if their resins are suitable for food use. FDA extractables testing can be used to empirically evaluate the migration rate of contaminants from plastics.The FDA has also described a mathematical approach for evaluating contaminant migration from plastics into food. The purpose of this research was to determine whether migration of contaminants from recycled PET would exceed the threshold of regulation and, if so, what thickness of virgin polymer would restrict migration to an acceptable level (a functional barrier). The surrogates officially selected for analysis were tetracosane, malathion,and butyric acid. Copper (11) 2-ethylhexanoate was used as a heavy metal surrogate. Benzene had the fastest permeation rate of all the surrogates. If benzene were allowed to absorb into a PET container for 2 weeks at 40 C and the container was cleaned, dried and remade into a 100% recycle content container, there would be 120 ppb contamination of the food supply. All other compounds would be present below the limit of detection. The approach appeared useful for estimating worst-case diffusion of model compounds into foods contained in PET containers.