How are shellfish beds classified?

Shellfish beds are classified according to the levels of bacterial contamination in shellfish flesh. An indicator of faecal contamination, E. coli, is used to measure contamination levels.  Harvesting areas are classified as follows:

Class A – an area in which molluscs contain consistently less than 230 E coli per 100g of flesh.

Class B – an area where 90% of samples have less than 4,600 E coli per 100g of flesh; the remaining 10% of samples must not exceed 46,000 E coli per 100g of flesh.

Class C – an area where molluscs must contain less than 46,000 E coli per 100g of flesh.

Prohibited area – an area where levels are higher than 46,000 E coli per 100g of flesh.