Flame retardants may up the risk of women, especially those in the postmenopausal stage, to develop thyroid disease, a new study has found.

The research is the first to suggest a connection between increased risk of thyroid disease in postmenopausal women and flame retardant chemicals known as polybrominated diphenyl ethers (PBDEs).

"These chemicals are just about everywhere, from the blood in polar bears to eagles to humans on every continent," says study lead author Joseph Allen from Harvard Chan School. The almost pervasive exposure means that all people are part of the global experiment on the effects of the endocrine system interfering bodily chemicals.

Looking At The Impact Of Flame Retardant Chemicals

To investigate, the research team analyzed a nationally representative group of women. They compared the four common PBDEs found in the blood samples of the participants from 2003 to 2004 and their record of thyroid problems.

Findings showed that all in all, women are approximately five times more prone than men to have a thyroid problem, with 13 to 16 percent occurrence rate in the former and 2 to 3 percent in the latter.

For women alone, those with the highest levels of flame retardant chemicals are more likely to have a thyroid problem than those with lower levels of the chemicals. For postmenopausal women, the size of affected individuals are doubled.

Flame Retardants

For decades, PBDEs have been used as flame retardants. Particularly, they are used in furniture, comprising about 20 percent of the products' weight.

As time passes, these chemicals are released from the furniture into the air and subsequently end up in homes, offices, outdoors and even in people's bodies.

In the past, studies have found that PBDEs settle in fat tissues and disrupt the actions of hormones, including thyroid hormones. Because the female hormone estrogen is known to control the amounts of thyroid hormones, the team speculates that postmenopausal women are more susceptible to the thyroid effects of PBDEs.

Allen explains that these chemicals act as if they are internal chemicals in the body. He does not think people should be shocked upon seeing women with high levels of PBDEs to have downstream health impacts as this is a given, yet it is preventable.

The study was published online in the journal Environmental Health on May 24.