Findings worrisome because thyroid hormones play critical role in fetal development, researchers say
MONDAY, June 21 (HealthDay News) -- Exposure to flame-retardant chemicals may reduce a pregnant woman's levels of certain thyroid hormones that play a critical role in fetal brain development, a new study shows.
Polybrominated diphenyl ether (PBDE) flame retardants are used in a large number of consumer products, including cars, electronics and home furnishings. PBDEs are found in the blood of most Americans, according to data collected by the U.S. Centers for Disease Control and Prevention.
In the new study, published online June 21 and in an upcoming print issue of the journal Environmental Health Perspectives, researchers from the University of California, Berkeley, measured thyroid hormone levels in 270 women, most of them Mexican-American, and found that those with higher PBDE levels had lower levels of thyroid-stimulating hormone.
Women with the highest levels of the flame retardant in their blood were more likely to have subclinical hyperthyroidism, which is defined as below-normal levels of thyroid-stimulating hormone with normal levels of the thyroid hormone thyroxine (T4), the researchers found.
"Women with low [thyroid-stimulating hormone] may be above their natural set-point for the T4 thyroid hormone, which means that their thyroids may not be functioning normally," study author Jonathan Chevrier, of the Center for Children's Environmental Health Research at University of California, Berkeley, said in a news release from the journal's publisher.
"Elevated T4 in pregnancy has been associated with increased risks of miscarriage, premature birth and intrauterine growth retardation," study co-author Brenda Eskenazi added.
"A mother's thyroid hormones affect her developing baby throughout her pregnancy, and they are essential for fetal brain development," Eskenazi, director of the Center for Children's Environmental Health Research, stated in the news release.
The U.S. Agency for Toxic Substance and Disease Registry has more about PBDEs.
-- Robert Preidt
SOURCE: Environmental Health Perspectives, news release, June 21, 2010
All rights reserved