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Review of Approaches for Establishing Exclusion Zones for Shellfish Harvesting around Sewage Discharge Points


<p>The study will review published and unpublished scientific literature relating to the setting and management of exclusion zones (preventing oyster harvesting) to mitigate viral risks from point source sewage discharges. The review will include a comparison between norovirus and other viral models with respect to environmental degradation and bioaccumulation factors, and also consider the significance of wastewater discharges from diffuse sources (eg boats and canoes) and their capacity to be controlled by norovirus exclusion zones. Review activities will incorporate the essential elements of a systematic review supported by direct contact with known working groups.</p>

<p>Overseas experience with respect to exclusion and buffer zones from European settings and United States National Shellfish Sanitation Program (US/NSSP) based suppliers will also be reviewed. Remote contact will be undertaken using a questionnaire to construct a database. Where positive examples are identified information will be sought to generate case study illustrations where possible.</p>

<p>An assessment of the level of the potential impact exclusion zones may have upon the UK oyster industry will be carried out. This will include construction of a UK-wide database of oyster harvest bed status using available information (e.g. shellfish hygiene classification, sanitary survey and pollution reduction plan data) and gathering of shellfish industry opinion on management options/business stability.</p>

<p>The study will also aim to assess whether existing computer modelling tools previously developed to meet E.coli environmental regulatory requirements in the Shellfish Water Directive can be utilised for norovirus ‘exclusion zones’. This part of the project will include a sensitivity analysis for the potential extent of prospective exclusion zones to meet a range of potential shellfish flesh norovirus standards using outputs from the literature review. Additional data requirements and future model developments that may be required to adapt models for this purpose will be identified.</p>

<p>The potential for developing a generic viral risk management matrix for use by harvesters that incorporates an exclusion/proximity component will also be evaluated.</p>

More information

<p>Background: Raw bivalve shellfish are widely recognised to be a high risk commodity with regard to viral contamination and norovirus in particular, although the relative contribution of different sources and transmission routes (including foodborne transmission) to the overall burden of norovirus in the community is not yet established.</p>

<p>The European Food Safety Authority (EFSA) has recommended that control options to reduce the risk from norovirus contaminated oysters should focus on preventative approaches that avoid viral contamination. EFSA suggested several potential preventative control options. These included the introduction of prohibition zones (‘exclusion’ or ‘buffer’ zones) around sewage discharges where shellfish may not be harvested. Exclusion zones are likely to be a key risk management option for further consideration at European Union (EU) level.</p>

<p>The study will provide an evidence base to inform development of UK policy in respect of possible establishment of exclusion zones and contribute to risk management discussions within the EU. </p>

Aquatic Water Service
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