Exposure to common flame retardant may lead to thyroid disorder in pregnant women
Women who have been exposed to high levels of polybrominated diphenyl ethers (PBDE), a common flame retardant, may experience altered thyroid levels during pregnancy, according to a new study published in the journal Environmental Health Perspectives
. This compound - which is used in carpets, textiles, foam furnishings, electronics and plastics - can be found in the blood of more than 97 percent of U.S. residents, although few studies have examined their impact on human health.
Researchers from the University of California (UC), Berkeley analyzed blood samples from 270 women taken around the end of their second trimester of pregnancy. They measured concentrations of 10 PBDE chemicals, two types of thyroxine (T4) and thyroid-stimulating hormone (TSH). They controlled for factors such as maternal smoking, alcohol and drug use, and exposure to lead and pesticides.
Results showed that a 10-fold increase in each of the PBDE chemicals was associated with decreases in TSH ranging from 10.9 percent to 18.7 percent. All the women in the study with low TSH levels had normal free T4 levels, which corresponds to subclinical hyperthyroidism. The study found that the odds of subclinical hyperthyroidism were increased 1.9 times for each tenfold increase in PBDE concentrations.
"Though the health effect of subclinical hyperthyroidism during pregnancy is not well understood, maternal clinical hyperthyroidism is linked to altered fetal neurodevelopment, increased risk of miscarriage, premature birth and intrauterine growth retardation," said the study's lead author, Jonathan Chevrier, a UC Berkeley researcher in epidemiology and environmental health sciences.