Toxicity of Sea Algal Toxins to Humans and Animals

Marine algal toxins are responsible of more than 60000 intoxication/year, with an overall mortality of about 1.5%. Human intoxications are due to consumption of seafood and respiratory exposure to aerosolized toxins. Algal toxins are also responsible for extensive die-offs of fish and shellfish, as well as mortality in seabirds, marine mammals and other animals depending on marine food web. Lots of information are available concerning acute intoxications, while little is known about environmental health effects of chronic exposure to low levels of algal toxins. Toxins are produced by two algal groups, dinoflagellates and diatoms, representing about 2% of known phytoplankton species (60-80 species out of 3400-4000) and can reach humans directly (via consumption of shellfish) or through food web transfer to higher trophic levels (zooplankton and herbivorous fish). Most toxins are neurotoxins and all are temperature stable, so cooking does not ameliorate toxicity in contaminated seafoods; five seafood poisoning syndromes exists: paralytic shellfish poisoning, neurotoxic shellfish poisoning, ciguatera fish poisoning, diarrhetic shellfish poisoning, and amnesic shellfish poisoning.