Exposure to Flame Retardant Chemicals May Increase Thyroid Problems in Women

Women with elevated levels of common types of flame retardant chemicals in their blood may be at a higher risk for thyroid disease; and the risk may be significantly higher among post-menopausal women, according to a new study published online May 23, 2016, in the journal Environmental Health from researchers at Harvard T.H. Chan School of Public Health. The new paper is the first to suggest a link between polybrominated diphenyl ethers (PBDE) and increased risk of thyroid problems in that population in a nationally representative sample of women in the U.S.

Thyroid problems include hyperthyroidism, hypothyroidism, goiter and Hashimoto’s disease. “These chemicals are just about everywhere, from the blood in polar bears to eagles to humans on every continent,” says Joseph Allen, assistant professor of exposure assessment science at the school and the study’s lead author. “This near ubiquitous exposure means we are all part of a global experiment on the impact of endocrine disrupting chemicals on our bodies.”

PBDEs have been used as flame retardants for decades, largely in furniture, bedding and curtains, in quantities of up to 20 percent of the weight of the product. Over time, they migrate out of the furniture into the air, settle into dust in homes, schools, offices and outdoors, and accumulate in people’s bodies. Previous research has shown that these chemicals accumulate in fatty tissue and interfere with hormonal functions, including thyroid hormones. Because it’s known that estrogen levels regulate thyroid hormones, researchers theorized that post-menopausal women may be particularly vulnerable to PBDE-induced thyroid effects.

The researchers found that overall, women were about five times more likely than men to have a thyroid problem. The percentage ranged from 13 to 16 percent among women, compared with 2 to 3 percent among men. Women with the highest flame retardant concentrations in their blood were significantly more likely than those with lower concentrations to have a thyroid problem. The effect was doubled in post-menopausal women.

“To our bodies, these flame retardant chemicals look and function exactly like endogenous hormones our bodies produce. Should we be surprised that we see downstream health effects for women with higher body burdens of these chemicals? I think not. This is all too predictable and preventable,” says Allen.

Todd Datz is the senior director of news and communications at Harvard School of Public Health. This article was reprinted from hsph.harvard.edu.