Food toxicological impor tance of marine and fresh water biotoxins. Part II: Fish and fishery products Literature review

SUMMARY The authors summarise the chemical, toxicokinetic, toxicological and clinical properties and characteristics of biotoxins (ciguatoxins, tetrodotoxin) and bio genic amines (histamine) found in marine and freshwater fish. Biotoxins pro duced by different dinoflagellates can also be found in the body of fish and can be taken up by nutrition. However, certain fish species produce toxins that are stored in their organs and tissues. Generally, these toxins are heat-stable and resistant to gastric juice. Ciguatoxins are lipid soluble and distributed in the whole body of fish. Basically, they bind to the voltage-dependent sodium channel causing depolarisation of the membrane due to sodium influx. Consequently, they increase the influx of calcium and water into the cell leading to muscle contraction, release of neu rotransmitters, decrease of nerve stimulation and paralysis. Characteristic signs of the toxicosis are paraesthesia, nervous system signs, gastro-intestinal prob lems, and rarely cardiovascular alterations. Tetrodotoxins are particularly concentrated in the offal of fish (liver, ovary, intes tines) and the skin with lesser extent. They are potent neurotoxins and block the voltage-gated sodium channel and therefore the influx of sodium, however, having no effect on potassium ions. The symptoms of intoxication include numbness at orofacial area, paraesthesia, gastro-intestinal signs, incoordination, unable to move and general paralysis. The freshwater biotoxins produced by blue algae do not accumulate in different vectors. They act rather by direct contact with the human body and have differ ent biological effects (e.g. hepatotoxic, neurotoxic). Scombrotoxin (histamine) is a biogenic amine with potent biological action that is produced during the normal metabolism of fish or due to microbial decarbox ylation. It may be present in large quantities in fishery products which may be harmful but not fatal to the consumers. The legal official regulations which are important from the aspect of consumer’s health care are also reviewed