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San Francisco Estuary Institute, EPA Release Report on Contamination of San Francisco Bay Fish

Release Date: 7/23/2003
Contact Information: Leo Kay, EPA Press Office, 415/947-4306, Mike Connor, SFEI, 510-746-7359, Jay Davis, SFEI, 510/746-7368

     SAN FRANCISCO   The San Francisco Estuary Institute and the U.S. Environmental Protection Agency released the results of long-term monitoring today revealing that contaminant levels in several Bay sport fish continue to exceed health guidelines.

     The most extensive analysis to date on contamination trends in Bay fish, the report shows that some pollutants in sport fish such as DDT and chlordane are on the decline, while others such as flame retardants (PBDEs) may be increasing based on preliminary data, and other persistent contaminants, such as dioxins, PCBs, mercury and selenium show no clear signs of change. The work was performed under the institute's regional monitoring program, with additional funds contributed by the EPA as part of a larger agency effort to better understand dioxins contamination in the Bay.

     Scientists sampled white croaker, shiner surfperch, leopard shark, California halibut, white sturgeon, striped bass and jacksmelt from the South Bay, Oakland Harbor, San Leandro Bay, San Francisco waterfront, Berkeley and San Pablo Bay.  Fish routinely exceeded health screening guidelines for PCBs, mercury, dioxin, dieldrin, selenium. Residues of a contaminant of emerging concern   the flame retardant compounds, PBDEs   were also detected in all samples. The results showed white croaker, surfperch and striped bass all routinely containing low levels of dioxins, including dioxin-like PCBs.

     Based on the sampling results, EPA and state officials are recommending that people who eat fish from the Bay continue to adhere to the fish advisory issued by the California Office of Environmental Health Hazard Assessment in 1994.  Adults should eat no more than two meals per month and no striped bass over 35 inches.  Children under six and women who are pregnant, breastfeeding or may become pregnant should eat no more than one meal per month, and should not eat any striped bass over 27 inches or any shark over 24 inches.  

     "We want to keep the public well-informed of the continuing levels of fish contamination in the Bay, and urge those who consume fish from the Bay to be aware of the state's health advisory," said Alexis Strauss, director of the Water Division in the EPA's Pacific Southwest Region in San Francisco.  "The EPA will continue to work with its federal, state and local partners to better understand how many of these contaminants, including dioxins, enter the environment and food chain, and continue to develop ways to address contamination at the source."

     "Once highly persistent contaminants such as mercury and PCBs enter the Bay they are very slow to leave," said Dr. Jay Davis, manager of the Institute's Regional Monitoring Program. "Chlordane and DDT seem to be less persistent and are gradually dissipating below levels of concern.  If PBDEs turn out to be persistent and their concentrations are rising in the Bay food web, then this may signal the beginning of a long term problem."
     The study found that both fish length and fat content were important factors in contaminant accumulation. Fattier fish species such as shiner surfperch and white croaker showed higher levels of PCBs and other organic contaminants, and larger fish species, especially leopard shark, showed higher levels of mercury contamination.

     Anglers can reduce exposure to some contaminants by avoiding fatty tissues such as skin and organs.  Anglers can also reduce exposure by consuming species such as Pacific salmon that accumulate generally lower concentrations of contaminants.  Guidance for preparing fish in ways that reduce exposure to contaminants, as well as the complete text of the consumption advisory,is available at the OEHHA website:

     To better understand contaminants in Bay fish, SFEI will perform another round of sampling this summer.

     "Additional sport fish species, such as anchovies, salmon, brown smooth-hound shark, and several species of surfperch will be included in this sampling," said Ben Greenfield, lead author of the report.

     The full report "Contaminant Concentrations in Fish from San Francisco Bay, 2000" can be accessed at

                    EPA's Efforts on Dioxins

     The EPA is focused on further characterizing dioxins in the Bay Area through emissions studies from fireplaces and wood stoves, and monitoring dioxins levels at numerous air sampling stations throughout the Bay Area with local and state air agencies.  The EPA also worked with Bay Area hospitals to implement an innovative pollution prevention program to lessen dioxins from local hospital waste.

     As a result of the state health advisory, the EPA listed the Bay in 1999 as a water body that fails to meet water quality standards for dioxins under the federal Clean Water Act. This listing requires the EPA and the California Water Quality Control Board to establish and implement pollution control measures to maintain water quality.

     The known major dioxins emitters in the country are hazardous waste and garbage incinerators, clusters of medical incinerators and garbage burning in barrels. In the Bay Area, there are a variety of smaller sources, such as diesel truck emissions and wood burning.

     For more information on the EPA's national and regional efforts to address dioxins
contamination, go to: