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Critical Review of the Current Evidence for the Potential use of Indicator Shellfish Species to Classify UK Shellfish Production Areas


<p>The objective of this desk-based study is to critically review and evaluate the currently available UK and international literature and other evidence, both published and unpublished, on the potential to use indicator shellfish species for faecal contamination classification purposes. An evaluation of the strength and robustness of the identified evidence is presented and knowledge gaps that might be addressed through future research work, to support indicator species use, are identified.</p>

<p>This study is intended to support a review and possible simplification of the official classification of shellfish production areas across the UK. For any of the shellfish species harvested to be considered a suitable indicator, and in order to protect public health, that species must be shown to consistently accumulate E.coli to an equal or greater extent than any other. Previous FSA workshops, involving relevant scientific experts from across the UK, have considered evidence available in support of potential options for changes to the current classification system. These have identified a certain amount of information (based on routine monitoring data from England and Wales) that showed mussels accumulate E.coli to a greater extent than some bivalve species, but not necessarily all. This critical review considers the amount and strength of wider evidence to support the suitability of mussels as a reliable indicator of uptake of E.coli in other commercially harvested bivalve molluscs and assesses the implications of adopting other indicator species options, together with any associated public health impacts. Options with regard to sampling effort for classification monitoring and impacts on classification status awarded to production areas are also presented.</p>

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<p>Background: Shellfish waters can become contaminated by sewage effluent discharges and surface water run-off from agricultural land, which may contaminate shellfish with pathogenic organisms known to cause human illness. EU food law requires a range of official controls for live bivalve molluscs to ensure that shellfish placed on the market are safe to eat. Statutory hygiene classification and monitoring of shellfish production areas, based on Escherichia coli as an indicator of faecal contamination levels, determines the extent of post-harvest processing required. Shellfish from more heavily contaminated sites are required to be relayed or depurated (cleansed in clean seawater) to reduce contamination to acceptable levels, or thoroughly cooked, before consumption.</p>

<p>In the UK, commercially harvested species within a production area are currently monitored and each species bed is individually classified. This is a costly and resource intensive exercise. The FSA is committed to reviewing this system to ensure it remains fit for purpose, utilises available resources effectively and provides adequate protection for public health. </p>

Centre for Environment, Fisheries and Aquaculture Sciences (CEFAS)
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