ABSTRACT
Intake of seafood inherently contaminated with saxitoxin and its homologues, the paralytic shellfish toxic metabolites, causes paralytic shellfish poisoning (PSPs). Toxicological levels are controlled worldwide, and in many countries, maximum permissible amounts in seafood have been determined. The PSPs are a group of naturally occurring guanidine-containing compounds produced by prokaryotes and eukaryotes in the ocean. These chemicals bind to and inhibit isoforms of the voltage-gated Na+ ion channel in mammals. Mouse based bioassay is an authorised procedure for measuring PSP levels in seafood, although instrumental methods of analysis are currently being used in many countries to replace it. Such studies give information on the amounts of numerous PSPs in seafood, but risk evaluation requires familiarity of the congeners’ relative toxicities. Toxicity Equivalence Factors (TEFs) are a way of expressing this (TEFs). Rather than acute toxicity assessments, TEFs are currently determined using relative specific activity in a mouse bioassay after intraperitoneal administration.
