Endocrine-disrupting Chemicals and Female Reproductive Disorders

August 26, 2016
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By Robert W. Rebar, MD
Professor and Chair, Department of Obstetrics and Gynecology, Western Michigan University Homer Stryker M.D. School of Medicine, Kalamazoo

SYNOPSIS: A European study finds that the endocrine-disrupting chemicals diphenyl-dichloroethene and phthalates significantly contribute to incidence of the common female reproductive disorders endometriosis and fibroids.

SOURCE: Hunt PA, Sathyanarayana S, Fowler PA, Trasande L. Female reproductive disorders, diseases, and costs of exposure to endocrine disrupting chemicals in the European Union. J Clin Endocrinol Metab 2016;101:1562-1570.

Chemicals that disrupt the body’s normal endocrine function can often precipitate seriously adverse developmental, neurological, immunological and reproductive defects. The Endocrine Society has reported that several endocrine disrupting chemicals (EDCs) have compellingly demonstrated their serious effects on ovaries and the reproductive tract. The EDCs in question are bisphenol A, phthalates, persistent organic pollutants (POPs) and even some pesticides. EDCs are often relatively common. Phthalates, for example, are found in small but measureable amounts in the human body. Pesticides are used around the world and, as such, their breakdown products are often prevalent in the environment.

Prior to conducting this study, the Endocrine Society handpicked a panel of experts to determine the combined healthcare and economic costs regarding adult exposure to diphenyl-dichloroethene (DDE, a chemical breakdown product of dichlorodiphenyltrichloroethane, a pesticide) and its association with fibroids, as well as the costs associated with adult phthalate exposures’ effects on incidence of endometriosis. The panel selected these two EDCs specifically because a wealth of information could be pulled from well-conducted studies examining the role of these chemicals in the development of female reproductive disorders, viewed through an exposure-outcome model. Peer-reviewed literature regarding EDC exposure provided information that allowed the authors to assess European exposure and approximate the overall impact of the disease for the year 2010. DDE exposure was also estimated with data gleaned from 12 European birth cohorts that measured cord and maternal blood levels. The cohorts allowed the assumption that women of reproductive age had similar blood levels of DDE. The panel estimated phthalate exposure in Europe by extrapolating from a study assessing phthalate metabolites in urine from a general population sample. Lastly, the panel estimated frequencies of endometriosis and fibroids among reproductive women with the aid of several other peer-reviewed studies.

In spite of utilizing the best data available from recent studies, the panel was only able to conclude that the epidemiological evidence was of low strength and the toxicological evidence available was of moderate strength. The panel continued by asserting that potentially 20% to 39% of women with fibroids and endometriosis contracted their disorders in a manner associated with EDCs. Based on the estimated incidence rates, the panel calculated that in the European Union in 2010, 56,700 women with fibroids causally related to DDE exposure accounted for 163 million euros in surgical costs. The panel also estimated that in 2010, 145,000 cases of phthalate-linked endometriosis among women aged 20-44 had associated healthcare costs of over 1.2 billion euros.

As the panel notes, these findings are prefaced by the concession that these estimations can approximate only direct costs that only extensively researched EDCs pose the European Union, meaning that it is likely that EDCs could be an even greater women’s health concern. Likewise, as the analysis only focused on adult exposure, it is possible that fetal exposure to EDCs can be detrimental. Indeed, there is an expanding evidence base for the claim that fetal EDC exposure can be linked to reproductive abnormalities in the adult. As there is a high likely there are many yet-unknown EDCs that can potentially affect the development of many reproductive diseases and disorders, the panel concluded its study by opining that its analysis and findings are potentially only the “tip of the iceberg.”