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Chemicals threaten wildlife in San Francisco Bay, scientists say

Jane Kay, Chronicle Environment Writer
October 2007

Scientists are closely monitoring flame retardants and commonly used pesticides in San Francisco Bay, as rising levels of toxic chemicals threaten birds, fish and marine mammals, according to an annual regional monitoring report set for release today.

Mercury, PCBs, dioxin and invasive species remain at the top of the most-wanted list of nasty threats to the bay, says the “Pulse of the Estuary 2007” report prepared by the San Francisco Estuary Institute, a nonprofit science group in Oakland. Scientists have long recognized that these problems in the bay impair the quality of its fish and wildlife and affect the working of the food chain. Yet, over the last several years, the concentrations of bromine-containing chemical flame retardants known as PBDEs have risen in both water and soil on the bay bottom, the report said.

The state Legislature banned two forms of flame retardants, “octa” and “penta,” effective in 2008. A third form, “deca,” which is widely used in electronic products, hasn’t been banned.

State health officials have found the chemicals in the bodies of marine mammals and in bird eggs and dead embryos and are concerned that the chemicals will interfere with reproduction, a danger observed in laboratory animals.

The synthetic insecticides, pyrethroids, are used in lawn products, outdoor sprays and on crops, including one called bifenthrin, which has been shown to kill the small crustaceans eaten by fish and amphibians. The state Department of Pesticide Regulation is reviewing documents on hundreds of pyrethrin products to assess their safety.

The report names pyrethroids, toxins from blue-green algae, invasive species and effects of the water projects as possible factors leading to the decline of four bay fish species – striped bass, longfin smelt, threadfin shad and delta smelt. The Bay Area faces significant costs in repairing and improving infrastructure that delivers drinking water and treats wastewater, the report said.

Cleaning up contaminants and trash, protecting wetlands and adjusting to climate change are other problems facing the Bay Area, it said.

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To view the San Francisco Estuary Institute’s
“Pulse of the Estuary 2007” report, go to: