The state Department of Public Health is advising people not to eat recreationally harvested mussels, clams or whole scallops from Marin County coastal waters.

Dangerous levels of naturally occurring paralytic shellfish poisoning toxins have been detected in mussels in the county, while clams and scallops may also pose a health risk, said Anita Gore, a state health spokeswoman.

The toxins can cause illness or death in humans.

The warning does not apply to commercially sold clams, mussels, scallops or oysters. State law permits only certified commercial shellfish harvesters or dealers to sell the products. Shellfish sold by certified harvesters and dealers are subject to frequent mandatory testing.

But recreationally harvested shellfish can store the toxin for several weeks after being exposed to toxic algal blooms and cause illness if consumed.

“The toxin levels may be influenced by a variety of environmental factors, so it’s impossible to predict when or where they will occur,” said Corey Egel, spokesman for the public health department. “The length of this quarantine is unknown, as environmental conditions can change levels of toxins found in shellfish.”

The toxins affect the central nervous system, producing a tingling around the mouth and fingertips within a few minutes to a few hours after eating the 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. Cooking does not destroy the toxin.

To receive updated information about shellfish poisoning and quarantines, call the state’s toll-free Shellfish Information Line at 1-800-553-4133.

Contact Mark Prado via email at

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