2013-10-28 by Stephanie M. Lee from "San Francisco Chronicle" [http://www.sfgate.com/science/article/Report-Some-chemicals-in-S-F-Bay-near-levels-of-4933885.php]:
Pesticides, flame retardants and other chemicals used in homes and businesses have been found in San Francisco Bay at levels that could pose hazards to aquatic life if they go unchecked, according to a new report.
For now, none of the chemicals is present in concentrations alarming enough to be of "high concern," meaning they are unlikely to cause significant harm to water quality and the bay's inhabitants, according to the annual report from the Regional Monitoring Program, an environmental group that tracks contaminants in the bay.
"However, there are a number of chemicals that are showing up not too far from levels of concern, and that's the bad news," said Tom Mumley, assistant executive officer of the San Francisco Bay Regional Water Quality Control Board.
Those chemicals warrant further monitoring and stricter regulation, he said.
The Water Quality Control Board and other bay monitors, including the San Francisco Estuary Institute and companies and municipalities that discharge wastewater into the bay, published the report in advance of the biennial State of the San Francisco Estuary Conference. On Tuesday and Wednesday, scientists, policymakers and experts will meet in Oakland to discuss the findings and other issues affecting the bay.
A variety of sources -
Chemicals enter the bay from all kinds of sources. Pesticides used indoors to combat lice, pet parasites and other pests, for instance, travel through drains, into wastewater treatment plants and into bay waters. Outdoor pesticides used in agriculture and landscaping end up in urban storm-water drains that lead to creeks, rivers and then the bay.
The monitors identified many toxic substances, including mercury, which has long been known to exist in the bay and is a potential health threat to humans who eat fish contaminated with the chemical element. But they have not yet identified many compounds they found in the bay. The effects others have on the mollusks, fish, birds and other bay wildlife that are directly exposed or eat organisms that have absorbed them are unknown.
"There's a really big, long list of chemicals that we haven't measured yet, or we don't have good thresholds to interpret whether the concentrations out there are something to be alarmed about or not," said Jay Davis, a senior scientist at the San Francisco Estuary Institute. More than 100,000 chemicals are registered or approved for commercial use in the United States.
Insecticides, detergents -
One chemical the monitors are concerned about is fipronil, an insecticide that's increasingly being used to control pests around buildings and fleas on pets. Found in higher-than-usual concentrations in bay sediment, it could affect the delicate bay wildlife if allowed to build up, according to the report.
Pyrethroids, another family of insecticides used to combat fleas and bedbugs, aren't a big danger in the bay now, but they're widespread in the urban creeks that feed into the bay.
"It's theoretically just a matter of time," Mumley said. "The more they continue to be used, the more we'd expect them to be at high levels in the bay."
Also under scrutiny are alkylphenols, which are breakdown products of chemicals in household detergents and other cleaning products. Chemicals in this family - which are known endocrine disruptors that can interrupt the hormone system in mammals - were found in varying levels in mussels and the eggs of cormorants, and experts say they may contribute to the decline of fish populations in the bay. Perfluoro-octane sulfonate - which is used as a stain repellent on textiles, furniture and carpets - was detected in bay birds, seals, fish and mollusks. In mammals, exposure to this chemical has been associated with compromised immune systems, reproductive defects, neurotoxicity and cancer.
The report's authors say that stricter chemical regulations at the state or federal level can work, as evidenced by the flame retardants known as polybrominated diphenyl ethers. Once common in furniture and electronics, PBDEs are not chemically bound to the products that contain them, so they can break off into dust or air. Linked to neurodevelopmental problems in children, these chemicals were once detected in high amounts in some fish, mussels and birds' eggs in the bay.
'Success story' -
But national manufacturers voluntarily phased out certain mixtures of PBDEs in 2004, and California banned those compounds in 2008. Since then, local water regulators have watched levels drop.
"All these indicators are pointing toward a decline," Davis said, who called it a success story. "It's happened pretty quickly in response to the bans."
State of the bay -
Report: Every year, the groups that put together the "Pulse of the Bay" report focus on different aspects of monitoring data. Read this year's report at [www.sfei.org/content/pulse-of-the-bay-2013].
Conference: Attend the biennial State of the San Francisco Estuary Conference on Tuesday and Wednesday in Oakland. Details are at [www.sfestuary.org/SOE].