Flame retardants may alter hormones of pregnant women

By Marla Cone and Environmental Health News, June 21, 2010

High levels of brominated flame retardants can alter pregnant women’s thyroid hormones, which are critical to a baby’s growth and brain development, according to a California study published Monday. The study is considered important because it is the first human research showing a link between the ubiquitous chemicals and altered levels of the hormones in pregnant women. The effects on babies are unknown, but some researchers say it may lead to smaller fetuses, and reduce childen’s intelligence and motor skills. “Normal maternal thyroid hormone levels are essential for normal fetal growth and brain development, so our findings could have significant public health implications,” said Jonathan Chevrier, a University of California, Berkeley epidemiologist and lead author of the study, which was published in the journal Environmental Health Perspectives. The flame-retarding chemicals, polybrominated diphenyl ethers, or PBDEs, are widely found in furniture cushions, carpet pads, electronics and other common household items. They have been detected in about 97 percent of people tested; in the United States, levels are at least 20 times higher than elsewhere. The Berkeley epidemiologists tested the blood of 270 pregnant women in California’s Salinas Valley. The study is part of a larger project monitoring the health of pregnant women and children in the valley, which is predominantly a low-income, Mexican-American farm community. The women’s thyroid-stimulating hormone, or TSH, declined 16.8 percent for every tenfold increase in PBDEs. Low TSH suggests that the thyroid is producing too much hormone on its own. The reductions were found for every type of PBDE. The high exposures did not lead to clinical hyperthyroidism – a condition involving overproduction of thyroid hormones known to damage fetuses. But their rate of subclinical hyperthyroidism did increase. For every ten-fold increase of PBDEs among the women studied, their risk of subclinical hyperthyroidism doubled. Scientists do not know whether the thyroid effects were significant enough to harm their fetuses. Chevier said pregnant women who are clinically hyperthyroid have an increased risk of miscarriage, premature birth and reduced fetal growth. Also, in animal tests, hyperthyroidism in the mothers results in damaged brain development of their offspring. But it is unclear whether subclinical hyperthyroidism – the effect linked to the flame retardants – can damage fetuses. …

Flame Retardants May Alter Hormones of Pregnant Women