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Ecology & EnvironmentTop Pollutants in the San Francisco Bay
Cadmium: Clings to soils and organics in the Bay where it is taken up by flounder, crab and other life. Chronic exposure is associated with lung, kidney and heart disease, anemia and skeletal weakening. Sources are industry, fertilizers and mine wastes.
Copper: Biggest pollutant in treated sewage from business and domestic sources. Toxic to marine life, and accumulates in shellfish, interfering with reproduction. Probably not very toxic to mammals and birds.
Mercury: Dumped during old-time mining activities and as industrial waste. Accumulates in aquatic animals. Pregnant women told not to eat any fish or shellfish from the Bay in part because mercury can damage developing fetuses. Can cause disorders of nervous system, vision and speech.
Nickel: Not thought to be hazardous to humans when ingested in food or water, but since it can cause cancer when inhaled as a dust, it’s still under study as a problem in water. Discharged to Bay as industrial waste.
Selenium: Bay dwellers told not to eat more than 4 ounces duck meat per month taken near the North Bay because of refinery discharge contamination. Beneficial at minute amounts, can malform developing embryos in mammals and birds.
Silver: Causes reproductive damage to clams and shellfish. Probably not very toxic to mammals and birds.
Tributyl tin, or TBT: Once used in boat-bottom paints; still found on the Bay floor. Lethal to fish and shellfish.
Chlordane: Pesticides leaking into the Bay from Central Valley. Toxic to the nervous system and classes as a probable human carcinogen. Now banned, still persistent.
DDT: Once known as a miracle pesticide, banned 21 years ago because it runied bird reproduction by thinning eggshells. Manufacturing and crop spraying contaminated Bay. Toxic to the nervous system of mammals and insects. Probable human carcinogen.
PCBs, or polychlorinated biphenyls: Now banned insulator in transformers leaked to estuary. Responsible for chemical poisonings of humans as well as persistent global pollution of air, soil, water, fish and wildlife. Suspected for harming reproduction in harbor seals.
Polynuclear aromatic hydrocarbon: Petrochemical hydrocarbons in the Bay from refineries and spills include naphthenes, naphthalenes, benzopyrenes, fluorenes, and pyrenes. Found in animal lab tests to be toxic and probable human carcinogens.
“Top Pollutants in the Bay,” Bay in Peril (Examiner, October 1993), p. 7
Top Polluters in the Bay
- Farm field, mine and other runoff
- Urban storm-drain runoff
- Municipal sewage treatment plants
- Industrial waste discharges
- Air pollution on water
- Dredged material
- Spills
Bay in Peril (Examiner, October 1993), p. 6