New state guidelines advise consumers to avoid eating shiner perch and sharks caught in the San Francisco Bay because the fish contain high levels of contaminants.
An advisory released yesterday by the Office of Environmental Health Hazard Assessment said that shiner perch had high levels of PCBs, or polychlorinated biphenyls, and that sharks had high levels of mercury.
The office found medium to high levels of both contaminants in striped bass and white sturgeon. Fillets of brown rockfish, California halibut, Chinook (king) salmon, jacksmelt, red rock crab and white croaker contained lower levels of the contaminants.
In addition to specific serving suggestions for children, adults, and pregnant and breastfeeding women, the advisory says no one should eat fish from the Lauritzen Channel in the Richmond Inner Harbor. The channel was previously used to formulate, package and ship pesticides and is now part of a Superfund site for hazardous waste.
The findings come after 15 years of monitoring fish and shellfish in the bay, as well as migratory species from the Delta, and Sacramento and San Joaquin rivers. The recommendations build on and replace guidelines issued in 1994, which included fewer species and only one year of data.
Current levels of PCBs and mercury in fish do not appear to have changed much since then, said Sam Delson, a spokesman for the office.
"There are some variations from year to year, but that's a big part of the reason for this more comprehensive advisory," he said. The state will continue to monitor fish at three-year intervals.
The office, part of the California Environmental Protection Agency, monitored 14 species of fish and one of shellfish in several locations. They were analyzed for PCBs and flame retardants, as well as some pesticides and metals, that pose health concerns.
To avoid exposure to PCBs found in the fat and skin of fish, the office recommends eating only skinless filets. Consumers should also cook fish thoroughly and drain juices. When eating crab, the office says to avoid eating internal organs.
PCBs are a group of man-made industrial chemicals that enter the environment from spills, leaks and improper disposal. High levels of PCBs, which can build up in the skin and organs of fish, can be harmful to people's health.
Fish can also absorb high levels of mercury from industrial pollution, mining and the environment; the metal can permanently damage the brain, kidneys and developing fetuses.
Mercury in fish is of particular concern for women who are pregnant or breastfeeding, as well as children. For these consumers and women up to age 45, the state advises they never eat shiner perch or other surfperches, leopard or smoothhound shark, striped bass and white sturgeon from the bay.
For other fish and shellfish, safe serving sizes vary by sex and age. Consumers may safely eat two servings a week of fish with low contaminant levels or one serving of those with medium contaminant levels. A serving is generally about the size and thickness of your hand – about 1 ounce of fish per 20 pounds of your body weight.