Concentrating on PBDEs: chemical levels rise in women.

On the heels of a European Union announcement of a forthcoming ban on polybrominated diphenyl ethers (PBDEs) comes a report by researchers led by Myrto Petreas of the California Department of Toxic Substances Control that women in the San Francisco Bay Area have 3-10 times higher concentrations of the suspected neurotoxicants than women in other parts of the world [EHP 111:1175-1179]. Although the study involved relatively few subjects, it's among several reports suggesting that exposure to these chemicals is high among Americans of all ages, including women of childbearing age.

Little is known about the human health effects of PBDEs--which are used as flame retardants in household goods--because they've been widely used for only a couple of decades. Concern over human exposure stems from PBDEs' structural similarity to polychlorinated biphenyls (PCBs), banned industrial compounds that disrupt memory and learning. PBDEs are known to disturb the balance of thyroid hormone in rodents exposed in utero or posmatally, leading to learning deficits. Scientists speculate that the impact of PBDEs on humans might be similar.

Scientists have known for some time that PBDEs, like PCBs and other persistent organic pollutants, accumulate in fat. People are exposed to such chemicals mainly through consumption of meat, poultry, fish, and dairy products.

As part of their study, Petreas and her colleagues analyzed stored tissue samples collected during three separate epidemiologic studies of women living in the San Francisco Bay Area. The first group consisted of 420 mothers sampled between 1959 and 1966 in a study of in utero exposure to organophosphate pesticides. The second group consisted of 32 women aged 25-54 who were participating in a breast cancer study in the late 1990s. The third group consisted of 50 Laotian immigrants aged 19-40 who were participating in a study of organochlorine effects on menstrual function, also in the late 1990s.

The researchers measured BDE-47, a prevalent constituent of PBDEs, in samples from the three groups. They found no detectable PBDEs in serum samples from the early 1960s group. In samples of breast adipose tissue from the second group, they found BDE-47 concentrations ranging from 5.2 nanograms per gram (ng/g) lipid to 196 ng/g lipid, with a mean of 28.9 ng/g lipid. And in serum samples from the third group, they found concentrations ranging from less than 10 ng/g lipid to 511 ng/g lipid, with a mean of 50.6 ng/g lipid. The 10-ng/g level is the lowest concentration at which a laboratory can report results with confidence.

Concentrations in the 1990s groups were 3-10 times higher than those in similar populations in Japan, Sweden, Germany, and Norway. Petreas and her colleagues speculate that this may be due to California flammability regulations for polyurethane foam and textiles used in furnishings"(although these regulations do not require the use of PBDEs in particular).

At first the researchers predicted that the Laotian women's exposure came through the fish that was a regular part of their diet. But these women's concentrations of PCBs--which should also have been high if fish consumption were the route of exposure--were low relative to those of the U.S.-born women sampled during the same time period. The researchers therefore suggest inhalation or ingestion of household and office dust from goods treated with PBDEs as an alternative route of exposure.

The researchers conclude by calling for more studies on the effects of PBDEs, writing that "increasing body burdens, particularly in young women of reproductive age, pose a potential public health threat to future generations."