At certain times of the year, naturally occurring algae in the sea can experience algal blooms, which are not always visibly noticeable but involve a significant and rapid increase in the population of algae. Some algae in these blooms produce potent biotoxins which, with increased mass, can accumulate in filter-feeding bivalve molluscs and sometimes other shellfish (e.g. grazing gastropods).
Eating shellfish contaminated with marine biotoxins can pose risks to those consuming the food, and thereby to the seafood industry.
Cefas offers testing services for the major shellfish biotoxin groups that are subject to statutory testing by EU directive to ensure contaminated shellfish are not put on the market (EC regulation 854/2004). These are:
Paralytic shellfish poisoning (PSP) toxins
Lipophilic toxins, including those responsible for diarrhetic shellfish poisoning (DSP)
Amnesic shellfish poisoning (ASP) toxins
All our tests follow internationally validated protocols that are operated to the highest standards. We have a long-standing reputation for the quality of our customer service and ability to consistently deliver high-quality test results to a range of customers.
Cefas carries out a sanitary survey for all new bivalve production areas. This is an essential first step towards establishing a microbiological monitoring programme and includes evaluating the sources and types of microbiological contamination to help in the classification of each bivalve production area.
The outcome of a sanitary survey is a sampling plan that details the point(s) at which samples must be taken for classification of the new site. A representative monitoring schedule is also identified, including appropriate production area/classification zone boundaries.
Classification and microbiological monitoring
Bivalve mollusc harvesting areas are classified according to the extent of contamination shown by monitoring of E.coli in shellfish flesh. Treatment processes are stipulated according to the classification status of the area. The classification categories are:
Class A (≤ 230 E. coli/100g) – can be harvested for direct human consumption
Class B (90% of samples must be ≤ 4600 E. coli/100g; all samples must be less than 46000 E. coli/100g.) – can be sold for human consumption after one of the following steps:
Purification in an approved plant
Re-laying in an approved Class A re-laying area
EU-approved heat treatment process
Class C (≤ 46000 E. coli/100g) – can be sold for human consumption only after re-laying for at least two months in an approved re-laying area followed, where necessary, by treatment in a purification centre or an EU-approved heat treatment process
In all cases, the health standards in Annex III of EC Regulations 853/2004 and the microbiological criteria adopted under EC Regulation 2073/2005 must be met. Molluscs must not be subject to production or collected in prohibited areas.