Severe pain such as cramping during your menstrual cycle, pain during or after sex, and infertility are all symptoms associated with the gynecological disorder endometriosis. To date, physicians and researchers have yet to determine the exact cause of the condition, but have speculated that it may be linked to two banned organochlorine pesticides in the U.S. — beta-hexachlorocyclohexane (beta-HCH) and mirex. According to a recent study, women exposed to these two pesticides have a 30 to 70 percent increased risk of being diagnosed with endometriosis in their lifetime.

Organochlorine pesticides are effective against a variety of insects, but have been restricted by the U.S. because of their potential adverse effects on not just wildlife, but also human health. The Centers For Disease Control and Prevention says that these chemicals are fat soluble and found at higher concentrations in fatty food, particularly dairy products and fish.

Humans are likely to be exposed to mirex from eating fish from contaminated water or living in areas with soil contaminated by historic mirex manufacturing, disposal, or pesticide application. Since the chemical is not metabolized in the body, it can cross the placenta and be oozed out of breast milk, which could increase the risk of exposure to newborns.

Similar to mirex which has estrogenic properties, beta-HCH can accumulate in human adipose and breast tissues. The chemical poses as an environmental risk factor for the development of human breast cancers.

These organochlorine pesticides with estrogenic properties may act as hormone disruptors, altering uterine and ovarian function and thus increasing the risk of endometriosis.

Publishing in the journal Environmental Health Perspectives, researchers sought to observe the role of environmental chemicals — such as organochlorine pesticides — that have estrogenic properties and their effect on the risk of endometriosis. In the study, traces for 11 organochlorine pesticides and byproducts were examined by drawing and testing the blood of 248 women with endometriosis and then compared to 538 healthy women. The female participants ranged in age from 17 to 49, and the majority were white.

The women were divided into four groups based on the level of pesticide in each woman’s blood. Those who were in the second-highest exposure group for beta-HCH were found to have a 70 percent greater risk of the gynecological disorder than women with the lowest levels of the pesticide. The participants who had the highest levels of mirex had a 50 percent greater risk of endometriosis than women with the lowest levels.

When the researchers observed women with ovarian-specific endometriosis — uterine tissue growing in the ovaries — they found a 2.5 times greater risk for those with the highest blood levels of beta-HCH than those with the lowest levels of the pesticide in their blood, according to the report.

Speculation rises as to whether the levels of these pesticides found in the participants’ blood accurately reflect the concentrations that existed prior to the study. The researchers collected the blood samples of the women at an average of 1.2 years after endometriosis diagnosis.

"This research is important, as endometriosis is a serious condition that can adversely affect the quality of a woman's life, yet we still do not have a clear understanding of why endometriosis develops in some women but not in others," said Victoria Holt, Ph.D, principal investigator of the study and a member of the Epidemiology Research Unit in the Public Health Sciences Division at Fred Hutch, Medical Xpress reports. "Our study provides another piece of the puzzle."

Despite the restricted use or ban of organochlorine pesticides in the U.S., the researchers were surprised to find the chemicals were still detectable in the blood samples of the participants in the study.

"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,” said Kristen Upson, Ph.D., lead author of the study and a predoctoral research fellow in epidemiology at Fred Hutch.

In a similar study published in the journal Environmental Science & Technology, researchers found a possible link between the use of sunscreen containing benzophenone (BP)-type ingredients and the increased risk of being diagnosed with endometriosis. The sunscreen ingredient is said to mimic the effects of estrogen as small amounts of BPs can go through the skin and be absorbed into the blood.

Endometriosis affects up to 10 percent of American women who are of childbearing age, according to John Hopkins Medicine. The gynecological condition is most common in women in their 30s and 40s, but can occur in any teen or woman who has menstrual periods.

To learn more about endometriosis and its risk factors, click here.