Food toxicological importance of marine and freshwater biotoxins Part I: Live bivalves

Summary Biotoxins produced by marine algae are taken up by shellfish during the filterfeeding activity which remain and concentrate in their different organs, thus these toxins can become the part of the human food-chain presenting potential risk to consumers. Generally, the toxin-producing algae habitat in the sea at tropical and temperate climate all over the world, however, the presence of a certain toxin may be characteristic to a given region. The authors summarise the physical-chemical characteristics of different biotoxins (saxitoxin, gonyautoxins, okadaic acid, dynophysistoxins, azaspiracids, yessotoxins, pectenotoxins, domoic acid, brevetoxin, palytoxins, cyclic imines) as food contaminants detected in marine organisms, particularly in shellfish, and their toxicokinetic profile, mechanism of action and potential harmful effects. They are called phycotoxins and most of them are lipid-soluble, heat-stable, thus the cooking and other heat-treatment or freezing does not inactivate them. Some of them - e.g. saxitoxin - are highly potent poisons. From food-toxicological aspects the paralytic shellfish poison (PSP), the diarrhoeic shellfish poison (DSP), the amnesic shellfish poison (ASP) and the neurotoxic shellfish poisoning (NSP) are the most meaningful. Furthermore, the legal regulation of toxins aiming to the health protection of consumers is also discussed. Essentially, the presence of the phycotoxins in edible marine molluscs and fish species does not induce any alterations or abnormality detectable by organoleptic examination. The base of protection against them is based on the prevention and regulation of farming and harvesting of live bivalves. According to the legal limit values and assessment performed by European Food Safety Agency, the consumption of flesh of shellfish containing okadaic acid, azaspiracid, saxitoxin and domoic acid can cause diseases in human consumers