A recent study by U. California-Berkeley researchers links certain flame retardant chemicals found in clothing, cars, furniture, electronics and a host of other products to disrupted thyroid hormones in pregnant women, suggesting implications for maternal and fetal health.
The study, published Monday in the Environmental Health Perspectives journal and led by professor Brenda Eskenazi, is part of a larger study by the Center for the Health Assessment of Mothers and Children of Salinas.
Lead author Jonathan Chevrier, a UC Berkeley researcher in epidemiology and in environmental health sciences, said the study is the “first of a sufficient size” that looks into the health implications of exposure to the chemical polybrominated diphenyl ethers (PBDEs).
Researchers in the study analyzed blood samples of 270 women in their second trimester of pregnancy, measuring the concentration of 10 PBDE congeners, free thyroxine (T4), total T4 and thyroid-stimulating hormone (TSH).
Results showed that women with higher concentrations of PBDEs had a greater chance of having low TSH while having normal levels of T4, a state known as subclinical hyperthyroidism. Chevrier said that although the specific consequences of increased PBDE exposure are largely unknown, thyroid hormones play a key role in fetal development and brain development, and women suffering from hyperthyroidism could have potential miscarriage issues.
PentaBDE and octaBDE, two commercial mixtures of PBDEs mentioned by Chevrier, have both been banned by the state of California, but they can still be found in products made before 2004. Another mixture found primarily in electronics, decaBDE, is scheduled to be phased out entirely by 2013.
“One of the concerns, even before (the PBDEs) were analyzed, is that they have chemical structuring similar to thyroxine (T4), TCDs and DDTs,” Chevrier said. “Californians have the highest levels in the U.S. of these chemicals.”
The study itself noted a “paucity of human data regarding associations between exposure to PBDEs and maternal thyroid hormone levels during pregnancy.”
“The reason for that, we think, is because California has unique flammability standards that result in a higher likelihood that PBDEs will be used in products,” Chevrier said. “The chemicals tend to be found in articles that people buy and keep for a long time, such as couches, car seats, carpets … anything that contains foam.”
Ami Zota, a postdoctoral fellow in the UC San Francisco Program on Reproductive Health and the Environment, said fire-related deaths have decreased systematically due to an increase in non-chemical preventative measures such as smoke detectors and fire sprinklers.
“There’s not scientific evidence showing that the use of these chemicals have prevented fire-related death and injuries,” she said. “Thyroid hormone regulation during pregnancy is really critical to fetal development and growth. There are a range of options available to address fire-related injuries and deaths that don’t have these risks associated with them.”