Endometriosis affects 10 percent of reproductive-age women and can seriously affect a woman’s quality of life and cause infertility, according to University of Washington professor of epidemiology Victoria Holt. A new study of women in the Northwest shows that endometriosis is linked to organochlorine pesticides. While these pesticides are for the most part no longer used in the U.S. — with the exception of some doctor-prescribed lice treatments — their effects linger in the environment and wind up in the bodies of women. Other recent studies show that climate change may be increasing the effects of these legacy chemicals.

Organocholorine contamination has historically been found in the Willamette and other rivers in the Northwest. In the study in the journal Environmental Health Perspectives, 248 women newly diagnosed with endometriosis in the Seattle area showed “that despite organochlorine pesticides being restricted in use or banned in the U.S. 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,” according to researcher Kristen Upson. She adds that the take-home message from the study is that “persistent environmental chemicals, even those used in the past, may affect the health of the current generation of reproductive-age women.”

Endometriosis is when the tissue lining of the uterus grows outside of the organ and attaches to other structures such as the ovaries, fallopian tubes and pelvic cavity. The study says that organochlorine pesticides have been shown to have “estrogenic properties” in human tissue and non-human studies have shown they alter the function of the uterus and ovaries, as well as hormone production. Endometriosis is an estrogen-driven disease, Upson says. “We hope our findings will help inform current global policymaking to reduce or eliminate their use.”

Other recent studies show that global warming could be affecting the movement and levels of chemicals such as organochlorine pesticides in the environment. The series of studies in Environmental Toxicology and Chemistry, which missed the deadline for inclusion in the latest International Panel on Climate Change report, shows that climate change affects the release of chemical contaminants, how organisms acclimate and vulnerable communities.