Samples of bivalves, snails and crabs were examined to see the presence of any undesirable chemical substances and microorganisms. NIFES revealed the results for 2009 which shows that the shellfish were of good microbiological quality throughout and that the level of undesirables was generally low and not exceeding current regulatory limits. Chemical analyses were also carried out to determine the concentrations of copper, zinc, arsenic , selenium, silver, tin, lead, mercury and cadmium in bivalves and crabs, as well as DDT, PCB, dioxins, brominated flame retardants and PAH in shellfish.
The report of the examination shows that bivalve molluscs can absorb intestinal bacteria such as E.coli, enterococci and Salmonella if such bacteria are present in the water where the bivalves grow. Examination of these microorganisms can therefore reveal exposure to faecal pollution which could be a potential health risk. Among a total of 400 samples analysed for E. coli, 82 percent had concentrations of E.coli which were below the limit for classification as an A-location, while there were no findings of Salmonella in any of the 58 samples which were examined.
The examinations were carried on the samples collected throughout 2009 and consisted of 369 pooled samples of blue mussels, 17 of great scallops, ten of European flat oysters, two of cockles and two of periwinkles. In order to determine the presence of undesirable substances in blue mussels, a total of 59 samples were collected in 2009. In general, the analyses showed low concentrations of all of the different substances and the level was the same as in previous years. Six samples of muscle and gonad of scallops also showed low concentrations of undesirables.
The presence of metals in the edible crab was determined in two samples of claw meat and two samples of brown meat. The results showed the same levels as in 2007, with the exception of cadmium where the concentration was slightly higher in brown meat in 2009.
The purpose of the NFSA’s annual surveillance programme for shellfish is to ensure that bivalve molluscs which are harvested for consumption do not come from areas which are polluted by microorganisms which can cause disease or contain undesirable substances at levels above the regulatory limits.
