Updated: Mar 15, 2021
Domoic acid (DA) is an excitatory amino acid produced by diatoms that called Pseudo-nitzschiae, of which at least 14 strains are toxic; 1 it accumulates in filter-feeding molluscs (as well as certain crustaceans and finfish).
Acute exposure to DA is associated with amnesic shellfish poisoning (ASP), a syndrome characterized by both gastrointestinal and neurological manifestations and which led to three deaths in a 1987 Canadian Atlantic Coast outbreak.
The U.S. Food and Drug Administration (FDA), the European Food Safety Authority (EFSA), and Health Canada promulgated regulatory limits for DA 34 based on assessment of that outbreak.
Saxitoxin (STX)-group toxins are a group of closely related tetrahydropurines and mainly produced by dinoflagellates belonging to the genus Alexandrium such as Alexandrium tamarensis. STX cause paralytic shellfish poisoning (PSP) in humans, characterised by a range of symptoms from a slight tingling sensation or numbness around the lips to fatal respiratory paralysis. In fatal cases, respiratory arrest occurs 2 to 12 hours following consumption of contaminated shellfish.
Okadaic acid (OA)-group toxins are usually produced by planktons in the sea, and can contaminate shellfish, notably bivalve molluscs such as oysters, mussels, scallops, and clams. Contaminated shellfish may cause diarrhetic shellfish poisoning (DSP). [Note: DSP can also be caused by other toxins, not only OAtoxins.