Dangerous Levels of Paralytic Shellfish Poisoning (PSP) Toxins Have Been Detected in Mussels from Humboldt

Mussels [Photo from the California Department of Public Health (CDPH)]

Dangerous levels of paralytic shellfish poisoning (PSP) toxins have been detected in mussels from Humboldt and San Luis Obispo counties. The naturally occurring PSP toxins can cause illness or death in humans. Cooking does not destroy the toxin.

The California Department of Public Health (CDPH) is advising consumers not to eat sport-harvested mussels, clams, or scallops from Humboldt and San Luis Obispo counties.

This shellfish safety notification is in addition to the annual mussel quarantine. The annual quarantine applies to all species of mussels harvested for human consumption along the California coast, as well as all bays and estuaries, and will continue through at least October 31.

The warning against eating sport-harvested bivalve shellfish (including mussels, clams, and scallops) from San Mateo County remains in effect, due to elevated levels of PSP toxins detected in mussels from the Pacific coast of the county.

This warning does not apply to commercially sold clams, mussels, scallops, or oysters from approved sources. State law permits only state-certified commercial shellfish harvesters or dealers to sell these products. Shellfish sold by certified harvesters and dealers are subject to frequent mandatory testing to monitor for toxins.

PSP toxins affect the central nervous system, producing a tingling around the mouth and fingertips within a few minutes to a few hours after eating toxic shellfish. These symptoms are typically followed by loss of balance, lack of muscular coordination, slurred speech, and difficulty swallowing. In severe poisonings, complete muscular paralysis and death from asphyxiation can occur.

You can get the most current information on shellfish advisories and quarantines by calling CDPH’s toll-free Shellfish Information Line at (800) 553-4133 or viewing the recreational bivalve shellfish advisory interactive map. For additional information, please visit the CDPH Marine Biotoxin Monitoring Web page. ​

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