Dar seafood ppp standard

Neurotoxic shellfish poisons

Neurotoxic shellfish poisoning is the result of exposure to a group of polyethers called brevetoxins from the unarmoured dinoflagellate Gymnodinium breve. Similar dinoflagellates have also been identified in low concentrations in Victorian, South Australian and West Australian waters with recent evidence suggesting that raphidophyte blooms of Chattonella marina, and possibly the related genera Fibrocapsa and Heterosigma, can also produce brevetoxin-like compounds (Hallegraeff 1998).

Hazard identification and characterisation: Brevetoxins and their derivatives exert their toxic effect by specific binding to site-5 of voltage-sensitive sodium channels (ANZFA 1999a). The toxins implicated in neurological shellfish poisoning are considered to be primarily ichthyotoxins (fish killing toxins) (Hallegraeff 2003). In humans, the symptoms of a mild case of neurotoxic shellfish poison intoxication include chills, headache, diarrhoea; muscle weakness, muscle and joint pain; nausea and vomiting after a few minutes to 3–6 hours after ingestion (Hallegraeff 2003). Symptoms can last as long as 2–3 days (FDA 2003). An extreme case can cause paraesthesia; altered perception of hot and cold; difficulty in breathing, double vision, trouble in talking and swallowing. No human fatalities from brevetoxin poisoning have ever been reported (Hallegraeff 2003).

Recovery is complete with no after effects and is generally not life threatening.

Respiratory problems in humans occur at about 10⁵–10⁶ cells/litre, while fish mortality occurs at >10⁶ cells/litre (Hallegraeff 2003). Toxin concentrations in shellfish during the 1993 New Zealand shellfish poisoning outbreak reached 592 MU/100 g (Hallegraeff 2003).
Incidence of human illness: Neurotoxic shellfish poisoning is usually associated with the consumption of contaminated shellfish (FDA 2003). Until recently all reports were endemic to the Gulf of Mexico and the east coast of Florida (Hallegraeff 2003). In 1993 a neurotoxic shellfish poisoning incident involving 180 people was reported in New Zealand. Concentrations of neurotoxic shellfish poisons reached 592 MU/100g (Trusewich et al. 1996).
Concentrations in seafood: In January 1994, mussels from Tamboon Inlet on the Gippsland coast of Victoria were found to contain 27.5 MU/100g in association with a G. breve type bloom (Arnott 1998). There is no other record of detection of neurotoxic shellfish poisons in Australia (ANZFA 1999a).
Current regulations: A maximum level of 200 MU/kg for neurotoxic shellfish poisons has been established in Standard 1.4.1 – Contaminants and Natural Toxicants – of the Code.
Ranking of hazard: Neurotoxic shellfish poison is ranked as ‘serious’ in terms of adverse health effects (Section 3, Table 3) because of its potential to cause incapacitating but not life-threatening illness following acute exposure.