Are chemical levels in San Francisco Bay going down?
The California Mussel Watch program has been measuring levels of contaminants in mussels throughout the state for over 15 years. Mercury levels in mussels have remained at essentially the same level during this time. Long term trends for DDTs, chlordanes and PCBs indicate that levels of these chemicals have steadily been going down since the beginning of the program. We expect these trends to continue because DDT was banned in 1972, chlordanes were phased out beginning in 1975, and PCBs were banned in 1979. Dieldrin and dioxins have not been measured through the California Mussel Watch program. Are some sites “safer” to fish from than others? Since this study was designed as a pilot study and not a comprehensive study, samples could only be collected at a limited number of locations. In addition, since different species were caught at different stations, a comparison of stations is difficult. However, some generalizations can be made: Vallejo-Mare Island was the sampling location from
