Dangerous chemical found in women's breasts
Bay Area levels higher than Europe, Japan

Jane Kay, Chronicle Environment Writer

Bay Area women have three to 10 times greater amounts of a chemical flame retardant in their breasts than either European or Japanese women, says a study by California scientists published Tuesday.

PBDEs, or polybrominated diphenyl ethers, are persistent organic pollutants that have been increasing worldwide in humans and wildlife over the last 10 years. The levels found in San Francisco Bay harbor seals are among the highest in the world.

Breast tissue and blood from 82 women examined at Bay Area hospitals in two studies in the late 1990s showed that they had levels higher than those found in Europe and Japan. There were no PBDEs in 420 archived samples collected in the 1960s, according to the study, which was released online in the Environmental Health Perspectives journal published by the U.S. Department of Health and Human Services.

PBDEs are a family of flame retardants used in polyurethane foam, textiles and plastic electronic casings. Laboratory studies have shown that the flame retardants mimic hormones and disrupt the endocrine system. They interfere with the thyroid gland and delay neurological development in the lab animals.

The form used in foam seems to be the one appearing in the breast tissue. But scientists can't say how people are exposed, said Myrto Petreas, lead author and a section chief with the Hazardous Materials Lab in the state Department of Toxic Substances Control.

"With pesticides, dioxins and PCBs, we believe that more than 90 percent of the exposure is through the diet," Petreas said. "In this case, with PBDEs, we speculate that one of the main pathways is from inhalation in dust from consumer products treated with PBDEs."

Other study authors are associated with the Public Health Institute in Berkeley, the state Department of Health Services, UC Davis and the San Francisco Department of Public Health.

The new studies raise questions whether the chemicals are contributing to higher than expected breast cancer rates in the Bay Area, particularly Marin County.

"We don't know," said Dr. Gina Solomon, a physician and senior scientist at the Natural Resources Defense Council in San Francisco. "The furthest we can go is to say that these chemicals need to be looked at carefully to see if they cause cancer in humans. They haven't even been looked at."

The government's National Toxicology Program is expected to release the results of animal studies within the coming year on cancer effects from PBDEs.

The PBDEs, Solomon said, are "the new PCBs" -- the banned chemicals once used as insulators in transformers, capacitors and hydraulic equipment that persist years later in the environment.

"If we don't do something now," Solomon said, "these chemicals will become our grandchildren's nightmare."

Last week, Solomon and representatives of the WaterKeepers of Northern California asked the U.S. Environmental Protection Agency offices in San Francisco to designate the PBDEs as impairing the bay. Such a designation would trigger stricter regulatory measures.

Last year, the San Francisco Bay Regional Water Quality Control Board stopped short of the designation and instead placed PBDEs on a "watch list."

Karen Taberski, a senior environmental scientist at the regional board, said the agency was very concerned about the pollutants.

"This is a big deal because these compounds are similar in structure and, we believe, toxicity to PCBs and dioxins," Taberski said. "They're increasing at a very quick rate in the environment. We've also found some of the highest levels in the world of PBDEs in marine mammals in the San Francisco Bay."

From 1989 to 1999, the quantity of PBDEs found in samples from 11 dead harbor seals stranded along the bay's shoreline increased by nearly a hundredfold, implying a doubling of concentration every 1.8 years. The San Francisco regional monitoring program is also finding PBDEs in white croaker and other fatty fish.

"It's a mystery how they're getting into breast tissue and into marine mammals," said Taberski. "We're trying to look into the regional sources and the pathways of exposure."