The California Department of Public Health (CDPH) is adding sport-harvested clams and whole scallops to the list of Del Norte County bivalve shellfish that consumers should avoid. The advisory is in addition to the annual mussel quarantine that was extended Oct. 31 for both Del Norte and Humboldt counties, according to CDPH.

“Dangerous levels of paralytic shellfish poisoning (PSP) toxins have been detected in mussels from this region; clams and scallops may also pose a health risk,” said the agency in a release. “The naturally occurring PSP toxins can cause illness or death in humans.”

CDPH noted that their warning does not apply to commercially sold clams, mussels, scallops or oysters from approved sources.

“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,” explained CDPH. “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. Cooking does not destroy the toxin.”

To receive updated information about shellfish poisoning and quarantines, call CDPH’s toll-free “Shellfish Information Line” at (800) 553-4133.

For additional information, please visit the CDPH Marine Biotoxins Frequently Asked Questions (FAQ) Web page.