(Beyond Pesticides, November 7, 2013) A study released this week established a strong connection between endometriosis and exposure to two dangerous pesticides: lindane and mirex. While the results are not surprising given past connections between these pesticides and their endocrine-disrupting effects, this new study, Organochlorine Pesticides and Risk of Endometriosis: Findings from a Population-Based Case-Control Study, is one of the first to examine the association between organochlorine pesticides (OCPs) and endometriosis, one of the most common gynecological diseases, in women in the general population.
The studyâ€™s authors, Kristen Upson, Ph.D. et al, Â explained to Environmental Health Perspectives, â€śOur study suggests that exposure from extensive past use of environmentally persistent OCPs in the United States, or present use in other countries may impact the health of the current generation of reproductive-age women with regard to a hormonally-mediated disease.â€ť
In conducting the study, researchers selected a group of women with surgically-confirmed cases of endometriosis from the greater Pacific Northwest area. This group of women was then divided into four groups, based on the level of pesticide in each womanâ€™s blood. Women in the second-highest exposure group for beta-hexacyclochlorohexane (beta-HCH), a byproduct of lindane, had a 70 percent greater risk of endometriosis than women with the lowest levels. Women with the highest levels of mirex had a 50 percent greater risk of endometriosis than women with the lowest levels.
Endometriosis is a disease in which tissue that normally grows inside the uterus grows outside the uterus. Patches of endometriosis, or the uterine tissue, respond to hormones in a similar way as the lining of the uterus. These tissues may bleed or have evidence of inflammation every month, similar to a regular menstrual period. However, the blood and tissue shed from endometriosis patches stay in the body and are irritants, which can cause pain. In some cases, inflammation and chemicals produced by the endometriosis areas can cause the pelvic organs to adhere, or stick together, causing scar tissue. Over time, some endometriosis areas may form nodules or bumps as they create lesions on the surface of pelvic organs or can become cysts (fluid-filled sacs) on the ovaries.Â These potential physical effects and symptoms generally result in pain and often infertility.
Current estimates from the Center for Disease Control (CDC) suggest that six to ten percent of women of reproductive age have endometriosis. This amounts to approximately 5 million women in the U.S. The CDC also notes that a 2011 National Institute of Child Health and Human Development (NIHCD) study indicates that these estimates are most likely low and that numbers may well exceed 5 million.
Endometriosis is only one of a potential range of endocrine-disrupting effects and diseases known to both national and world health organizations. Earlier this year, Beyond Pesticides reported on the State of the Science of Endocrine Disrupting Chemicals,Â a joint study by the United Nations Environment Programme (UNEP) and the World Health Organization (WHO), which emphasized that endocrine disrupting chemicals (EDCs) are important environmental risk factors for endocrine diseases. Exposures during critical phases of development play an important role in the onset of many diseases, such as endometriosis, affecting future generations. The UN study, one of the most comprehensive reports on EDCs to date, highlights some association between exposure to the full-range of EDCs and health problems.
While this latest study from Washington State adds to the pile of mounting evidence of endocrine-disrupting effects and risks associated with pesticides, it also adds to the pile of known health and environmental threats surrounding these two dangerous pesticides. Both lindane and mirex have been identified as persistent organic pollutants (POPs) by the U.S. Environmental Protection Agency (EPA) and by the parties of the Stockholm Convention, an international treaty established in 2001 to eliminate or reduce the release of POPs into the environment, with lindane being added to the list in 2009. EPA banned all uses of mirex in 1978 and canceled all pesticide registrations of lindane in 2006.
As demonstrated by the presence of mirex in the womenâ€™s bodies in this latest study (over two decades after the EPAâ€™s ban) and other recent environmental assessments, banning all uses and production of a POP or â€śbioaccumulativeâ€ť chemical will not prevent its presence in the environment or harmful effects for decades to come. This troubling fact means that every effort to stop all additional introductions of these dangerous chemicals into the environment should be made.
Unfortunately, women, children, and the U.S. population in general cannot take comfort in the fact that while much of the world has made these efforts, all sectors of the U.S. government charged with regulating these chemicals have not. The U.S. Food and Drug Administration (FDA) still permits lindane to be used in prescribed shampoos and lotions for head-lice and scabies treatment.
Pleas through an official petition from the environmental health community and advocacy organizations (initiated by the Natural Resources Defense Council (NRDC) and supported by Beyond Pesticides) and requests concerning this issue fromÂ Congressmen have fallen on deaf ears. Arguing that lindane is needed as a third-line stop gap for head-lice and scabies treatment, FDA chose to continue its approval of lindane as a pharmaceutical.Â In doing so, FDA continues to support the additional introduction of a pesticide that will impact future generations and the environment for decades to come.
To prevent the environmental and health impacts of pesticides like lindane and other EDCs, Beyond Pesticides advocates for the use of non- and least-toxic methods to control diseases like head lice and scabies. One of the safest methods to combat lice is to coat oneâ€™s hair with coconut oil and carefully pick through the hair with a nit comb, remembering to place the lice in hot soapy water after they have been removed from the hair. Another method is to use hot air, which desiccates the insects and eggs, ultimately killing them. A study from the University of Utah found this method outperformed insecticidal shampoos at killing adult lice and their eggs.Â These methods prove to be both safer and more effective.
For more information on controlling head lice without toxic chemicals, see Beyond Pesticidesâ€™ alternatives webpage and our fact sheets on Head Lice and Scabies and Getting Nit Picky about Head Lice.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.