Although large metropolitan areas such as Los Angeles and San Francisco come to mind when California, much of the state is agricultural—and pesticides are commonly used in these areas. A new study has found that exposure to two pesticides that are now banned can produce endometriosis. The findings were published online on November 5 in the journal Environmental Health Perspectives by researchers at the University of Washington (Seattle, Washington).
Endometriosis is a condition in which the tissue lining the uterus grows in other pelvic regions; it can cause pelvic pain, menstrual problems, and infertility. According to the American Congress of Obstetrics and Gynecology, it occurs in about 10% of women of reproductive age and is more commonly diagnosed in women in their thirties and forties. At present, it is unclear why some women develop endometriosis and others do not; however, it is known that the hormone estrogen stimulates its growth.
The researchers note that certain chemicals, including organochemical pesticides, have hormonal properties. They theorized that these properties might alter estrogen production in exposed women, resulting in an increased risk of endometriosis. They accessed data from the Women’s Risk of Endometriosis (WREN) study, which is a study of endometriosis conducted among 18-49 year old women who are enrolled in a large healthcare system in western Washington State. The study group comprised 248 women who had recently been diagnosed with endometriosis and 538 women without the disease.
Organochemical concentrations in the blood were measured in the two groups of women and compared. The investigators found that women who had high levels of exposure to two pesticides, beta-hexachlorocyclohexane and mirex, had a 30-70% increased risk of having endometriosis. Beta-hexachlorocyclohexane, was a chemical byproduct of an agricultural pesticide that was commonly used throughout the 1970s. The other chemical, mirex, was used in the 1960s and 1970s as part of an insect control program against fire ants; the chemical was aerially sprayed over millions of acres in the southeastern United States. Both chemicals were later banned because of concerns about their effect on the environment and human health; however, they are still present in the environment.
The investigators concluded that serum concentrations of beta-hexachlorocyclohexane and mirex were positively associated with endometriosis. They noted that extensive past use of environmentally persistent organochemical pesticides in the US or present use in other nations may impact the health of reproductive-age women.
Take home message:
This is yet another study that notes that pesticides not used for decades are still present in the environment and present a health hazard.