Marine Toxi

nsNatural Marine Toxins: PSP and Domoic Acid
Paralytic shellfish poisoning (PSP) toxins and domoic acid are naturally occurring marine toxins. Single-celled marine plants (phytoplankton) produce these toxins. Marine animals that filter their food from seawater may accumulate these toxins. The toxins do not appear to directly harm the animals, but people or some predatory animals eating toxic seafoods may become poisoned. PSP toxins and domoic acid are powerful nerve poisons. PSP toxins and domoic acid have no taste or odor. There is no visible difference between toxic and safe seafoods. Cleaning seafoods in many cases will not remove the toxins. Cooking does not destroy the toxins.

Paralytic Shellfish Poisoning Toxins
Certain one-celled organisms called dinoflagellates produce PSP toxins. Bivalve shellfish (2 shells) filter these organisms from the water. PSP toxins accumulate in the dark digestive organs or viscera of most shellfish. In Washington clams, PSP toxins also accumulate in the siphons (necks). Mussels, oysters, clams, and scallops have caused PSP outbreaks in California, but abalone, crab, shrimp and fish have never been implicated as a source of PSP. PSP symptoms begin within a few minutes to a few hours after eating toxic shellfish. Symptoms begin with tingling and numbness of the lips, tongue and fingertips. Later symptoms are lack of balance, lack of muscle coordination, slurred speech and problems in swallowing. Complete paralysis and death can occur in severe cases.

Domoic Acid
Domoic acid was only recently discovered (1991) in California. Certain one-celled plants called diatoms produce domoic acid. Bivalve shellfish and some finfish filter these diatoms from the water. In most cases, domoic acid accumulates in the viscera of these animals. In razor clams, domoic acid also accumulates in the meat. Unsafe levels of domoic acid have been found in mussels, oysters, razor clams and the viscera (but not in the muscle tissue) of sardines,...