Exposure to Pesticides Increases Risk of Endometriosis

Two organochlorine pesticides are associated with an increased risk of endometriosis among reproductive-age women, according to a study published in Environmental Health Perspectives, a journal of the National Institutes of Health.

The Fred Hutchinson Cancer Research Center-led study found that women with higher exposures to the pesticides beta-hexachlorocyclohexane and mirex had a 30% to 70% increase in endometriosis risk.

The study involved 248 women between 18 and 49 years of age in whom endometriosis was newly diagnosed. These women with endometriosis were compared with 538 women without the disease. The women were all enrolled in Group Health Cooperative, a Seattle-based nonprofit health care system.

The data showed increased endometriosis risk associated with serum concentrations of beta-hexachlorocyclohexane (third vs lowest quartile: OR, 1.7; 95% CI: 1.0, 2.8; highest vs lowest quartile, OR 1.3; 95% CI: 0.8, 2.4) and mirex (highest vs lowest category: OR, 1.5; 95% CI: 1.0, 2.2). In addition, the association between serum concentrations of beta-hexachlorocyclohexane and endometriosis was stronger when restricting cases to those women with ovarian endometriosis (third vs lowest quartile: OR, 2.5; 95% CI: 1.5, 5.2; highest vs lowest quartile: OR, 2.5; 95% CI: 1.1, 5.3).

"We found it interesting that despite organochlorine pesticides being restricted in use or banned in the US for the past several decades, these chemicals were detectable in the blood samples of women in our study and were associated with increased endometriosis risk," said the lead and corresponding author Kristen Upson, PhD, in a news release. "The take-home message from our study is that persistent environmental chemicals, even those used in the past, may affect the health of the current generation of reproductive-age women with regard to a hormonally driven disease."

Previous laboratory studies have shown that organochlorine pesticides have generally demonstrated estrogenic properties and can alter the function of the uterus and ovaries, as well as hormone production, according to the authors.

The authors attributed the exposure to either extensive past use of environmentally persistent organochlorine pesticides in the United States or current use in other countries.

"Given these actions, it's plausible that organochlorine pesticides could increase the risk of an estrogen-driven disease such as endometriosis," Upson said. "We hope our findings will help inform current global policymaking to reduce or eliminate their use."

The authors said their research provides an additional piece to the puzzle of why endometriosis develops in some women but not in others.

Pertinent Points:
- Two organochlorine pesticides, beta-hexachlorocyclohexane and mirex, are associated with an increased risk of endometriosis.
- The pesticides were detected in the blood samples of reproductive-age women in whom endometriosis was newly diagnosed.