California health officials are urging people to avoid eating shellfish gathered along parts of the Bay Area coast after dangerous toxins were found in local waters.
The California Department of Public Health said in a recent advisory shared by local officials Friday that consumers should not eat sport-harvested mussels, clams, scallops or oysters from Marin, Sonoma and San Mateo counties after testing detected high levels of paralytic shellfish poisoning, or PSP, toxins in mussels.
The toxins occur naturally in marine environments and cannot be removed by cooking, according to the department.
PSP toxins affect the nervous system and can cause symptoms within minutes to hours after eating contaminated shellfish. Early signs include tingling around the mouth and fingertips, followed by loss of balance, poor coordination, slurred speech and difficulty swallowing.
In severe cases, the poisoning can lead to paralysis and death from asphyxiation, the department said.
The warning applies only to shellfish collected recreationally, such as by people harvesting along beaches.
“This warning does not apply to commercially sold mussels, clams, scallops, and oysters from approved sources,” the department said, noting that licensed harvesters and dealers are required to test shellfish regularly for toxins.
Paralytic shellfish poisoning is often linked to naturally occurring algal blooms that produce toxins that build up in filter-feeding shellfish. State health officials monitor those toxins year-round and issue advisories when levels rise.
Anyone who develops symptoms after eating shellfish should seek medical care immediately, health officials said.