Domoic Acid Threat to Public Health from Razor Clams in Del Norte and Humbolt Counties

Recent test results indicate prompt action is needed to address an emergency situation involving a severe threat to public health and safety from the potential human cosumption of razor clams with high levels of domoic acid.

The Office of Environmental Health Hazard Assessment (OEHHA) has been provided test data from the California Department of Public Health (CDPH) laboratories measuring high levels of domoic acid in razor clams harvested along the coast of Del Norte and Humbolt counties (along Crescent and Clam beaches). Domoic acid poisoning in humans may occur within monutes to hours after consumption of affected seafood and can result in signs and symptoms ranging from vomiting and diarrhea to permanent loss of short-term memory (Amnesic Shellfish Poisoning), coma, or death.

The current federal action level for domoic acid in clams is 20 parts per million (ppm).  Data in razor clams collected this month from the coast of Del Norte and Humbolt counties show that all but one of the samples (17 out of 18) exceeded the action level of 20 ppm.  One-third of the samples were above 100 ppm.

In consultation with the Director of CDPH, OEHHA finds that consumption of razor clams is likely to pose a significant human health risk as a result of high levels of domoic acid.  As such, OEHHA recommends that the razor clam fishery be closed for Del Norte and Humbolt counties.

OEHHA anticipates making a recommendation to open the fishery of lift the closure based on further domoic acid testing conducted in clams at each of the sampling locations, to include two sets of samples, collected at least seven days apart that all test under the Food and Drug Administration (FDA) action level.

Please see the attachment for more information.

CDPH - CDPH Reminds of Warning on Razor Clams from Humboldt and Del Norte Counties