Scientific Opinion on marine biotoxins in shellfish – Emerging toxins: Ciguatoxin group
The EFSA Panel on Contaminants in the Food Chain (CONTAM Panel) assessed the risks to human health related to the consumption of ciguatoxin (CTX)-group toxins in fish. CTX-group toxins occur in fish as a result of biotransformation of precursor gambiertoxins produced by the benthic dinoflagellate Gambierdiscus toxicus. CTX-group toxins cause ciguatera fish poisoning. They are mainly found in Pacific, Caribbean and Indian Ocean regions and are classified as Pacific (P), Caribbean (C) and Indian Ocean (I) CTX-group toxins. Recently CTX-group toxins were identified for the first time in fish in Europe. Currently there are no regulatory limits for CTX-group toxins in fish in Europe, but the regulation requires that no fish products containing CTX-group toxins are placed on the market. The toxicological database for CTX-group toxins is limited, comprising mostly acute toxicity studies. In view of the acute toxicity of CTX-group toxins the CONTAM Panel considered establishing an acute reference dose (ARfD). However, due to the very limited quantitative data both in experimental animals as well as related to human intoxications, the CONTAM Panel concluded that the establishment of an oral ARfD was not possible. Based on case reports on human intoxications it appears that a concentration of 0.01 μg P CTX-1 equivalents/kg fish is expected not to exert effects in sensitive individuals when consuming a single fish meal. The mouse bioassay (MBA) has been widely used to detect CTX-group toxins. However, due to insufficient detection capability and ethical concerns the MBA is not considered an appropriate method. In vitro (cytotoxicity and receptor binding) assays have been developed as alternative, but they need further development. Liquid chromatography-tandem mass spectrometry methods can be of value for the quantification of CTX-group toxins, but certified reference standards and reference materials need to be provided to allow method development and (inter-laboratory) validation.