Women with high levels of pesticides in their blood are more likely to have endometriosis, according to a new study published in the journal Environmental Health Perspectives and reported by CNN.

Endometriosis is a chronic condition that affects more than 5 million, or 10 percent, of American women. The condition occurs when tissue lining the interior uterus walls grows outside the organ. Most commonly the extra tissue affects the ovaries, fallopian tubes or pelvis and can lead to infertility.

For the study, researchers took blood samples from 248 women with surgically-confirmed endometriosis and 538 women without diagnosed endometriosis and measured them for several organochlorine pesticides, or OCPs. Overall, 90 percent of women had detectable levels of one such pesticide, beta-HCH, in their blood.

What’s more, women with higher levels of beta-HCH in their blood were nearly 2.5 times more likely to have ovarian endometriosis. In addition, scientists found that another pesticide, Mirex, also increased a woman’s risk of endometriosis by 50 percent.

According to researchers, some OCPs seem to mimic estrogen in the body and may possibly contribute to the development of endometriosis.

OCPs were widely used in the United States from the 1940s through the 1960s until the Environmental Protection Agency (EPA) and the United Nations’ Stockholm Convention limited their use. But these pesticides are still present in the environment today and have accumulated in the food chain.

“We detected these chemicals in the blood of women despite their being banned or severely restricted in the United States for the past several decades,” said Kristen Upson, a post-doc fellow at the National Institute of Environmental Health Sciences and a study author.

Currently, beta-HCH can still be found in some dairy products, fatty foods and fish. In addition, this OCP is produced as a by-product of several lice shampoos and lotions.

Pesticide exposure may also cause attention problems in children. Click here  to read more.