Monitoring of Urban Coastal Areas Shows Widespread Moderate Methylmercury and PCB Contamination in Sport Fish
Press Release
Contact: Dave Clegern, Office of Public Information, 916-327-8239
State Water Board
05/26/2011
The State Water Resources Control Board's Surface Water Ambient Monitoring Program (SWAMP) has released findings from California’s largest-ever statewide survey of contaminants in sport fish from coastal locations. The survey found that methylmercury and polychlorinated biphenyls (PCBs) are the two greatest concerns.
This report presents findings from 2009 - the first year of a two-year survey - including new data for 42 locations. The survey focuses on sport fish because they provide information on human exposure and also the condition of the aquatic food web. Monitoring in 2009 centered on areas near Los Angeles and San Francisco, including San Francisco Bay.
Methylmercury accumulation in fish is a persistent problem throughout much of the state. Eight of 42 locations sampled had at least one fish species with an average methylmercury concentration that exceeded the Office of Environmental Health Hazard Assessment (OEHHA) threshold for considering a recommendation of no consumption for women of childbearing age and children. At all but one of the locations the highest concentrations were observed in sharks, which have a tendency to accumulate high levels of methylmercury worldwide.
Most of the locations sampled (33 of 42) had a moderate degree of methylmercury contamination. Methylmercury can affect the developing nervous system in children and adolescents, potentially leading to learning disabilities. Methylmercury contamination of California coastal waters likely originates from multiple sources, including, historic mercury, gold, and silver mining, regional and global emissions to the atmosphere, and urban and industrial wastewater and stormwater.
PCBs were comparable to methylmercury as a potential health concern to consumers of fish caught from California’s urban coastlines. Six of 42 locations sampled had at least one fish species with an average PCB concentration that exceeded the OEHHA threshold for considering a recommendation of no consumption.
San Francisco Bay and San Diego Bay stood out as having elevated concentrations. Most of the locations sampled (31 of 42) had a moderate degree of PCB contamination. Only five locations from more remote areas had concentrations lower than the lowest threshold. PCBs may cause cancer, damage the liver, digestive tract, and nerves; and affect development, reproduction, and the immune system. PCBs are persistent chemicals that are now banned, but were commonly used in electrical, industrial and other applications.
Other pollutants, including dieldrin, DDT, chlordanes, and selenium, were also found, but generally at low levels. This initial screening study is the first step in an effort to identify and quantify contaminants in California’s coastal waters to provide a detailed evaluation of human and wildlife exposure and to establish priorities for cleanup actions. OEHHA will not be able to develop new consumption recommendations based solely on data from this screening study – more thorough sampling will be required.
The Coast Survey was funded by the State Water Resources Control Board’s Surface Water Ambient Monitoring Program (SWAMP and the United States Environmental Protection Agency (USEPA). This survey was performed in close collaboration with the Southern California Bight Regional Monitoring Program and the Regional Monitoring Program for Water Quality in the San Francisco Estuary.
The Coast Survey is one component of a new program that is tracking sport fish contamination in all California water bodies. Results for another 27 coastal locations will be available in May 2012. Results from a statewide assessment of contaminants in sport fish from California rivers and streams will be available in May 2013.
