A Brief Review of Environmental Contaminant Effects on Female Fertility

By: Ryan Powley

Director’s Note: In this review of endocrine disruptors, former FACTS elective student Ryan Powley notes the fertility-related outcomes of common contaminants such as BPA, phthalates, and pesticides. Focusing specifically on the implications for female reproduction, Powley summarizes the article titled, “Environmental Contaminants Affecting Fertility and Somatic Health,” published by Chiang et al in 2017. [1] As a future physician, Powley plans to educate her patients on the implications for both male and female fertility and the need to limit exposure to specific contaminants.  To help us educate even more medical students about the  factors affecting fertility, please make a gift to FACTS today.

Introduction

In the article [1] titled, “Environmental Contaminants Affecting Fertility and Somatic Health,” Chiang et al describe findings published between 2011 and 2016 concerning various potential environmental contaminants that may affect male and female fertility, pregnancy outcomes, and reproductive health. Better known as endocrine disruptors, the contaminants studied include BPA (bisphenol A), phthalates, dioxins, pesticides, air pollutants, fracking chemicals, triclosan, and parabens. With the exception of triclosan and parabens, all the other endocrine disruptors had definitive associations with male or female infertility. Notably, in couples, parabens did reveal inferior fertility treatment outcomes; more research is needed with both triclosan and parabens to attain more decisive data. This brief summary focuses only on BPA, phthalates, and pesticides, and their effect on reproductive outcomes in women. These three contaminants were associated with cycle or follicle changes, poor fertility treatment outcomes, and conditions that affect female fertility such as polycystic ovary syndrome (PCOS), endometriosis, and uterine fibroids.

“BPA, phthalates, and pesticides … were associated with cycle or follicle changes, poor fertility treatment outcomes, and conditions that affect female fertility such as polycystic ovary syndrome (PCOS), endometriosis, and uterine fibroids.”

Contaminant Impact on Reproductive Outcomes

Bisphenol A (BPA)

BPA is used frequently in medical equipment, epoxy resins lining aluminum cans, polycarbonate plastics, and dental sealants. Thus, the most common route of exposure to this endocrine disruptor is via ingestion of food or beverages contaminated with BPA. Higher BPA levels were associated with anovulation and lower follicle counts. This has major implications for women who desire to achieve pregnancy, as ovulation is a pre-requisite to conception. Furthermore, it is more difficult, though not impossible, to achieve pregnancy in the setting of lower follicle counts or diminished ovarian reserve. BPA is also associated with worse outcomes in women undergoing assisted reproductive technologies (ART), specifically showing negative associations with number of oocytes retrieved, oocyte maturation, fertilization rates, and embryo quality.

“Higher BPA levels were associated with anovulation and lower follicle counts … [which] has major implications for women who desire to achieve pregnancy, as ovulation is a pre-requisite to conception.”

Phthalates

Phthalates are synthetic chemicals commonly used in cosmetics, medications, and plastic toys. Exposure can occur via ingestion, inhalation or dermal contact. Interestingly, phthalate metabolites are detected in more than 99% of urine samples, so exposure to these toxins is extremely prevalent. The phthalates included in this review are di-(2-ethylhexyl) phthalate (DEHP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and benzyl butyl phthalate (BBP). Of the phthalates, the reproductive effects of DEHP have been studied most extensively. As with BPA, phthalates were associated with fewer antral follicles and inferior outcomes with ART.

Pesticides

As a class, pesticides include herbicides, insecticides, and fungicides. Exposure occurs through inhalation, dermal or ocular contact, and ingestion of contaminated food, water or soil. Organochlorines are a type of pesticide that persists in the environment long after initial use and has been shown to bioaccumulate in the food web. Exposure to organochlorine pesticides was associated with shorter menstrual cycles, whereas exposure to non-organochlorine pesticides was associated with longer or absent cycles.

Ideally, the female cycle should be between 24 and 30 days; shorter or longer cycles outside these parameters may make it more difficult for a woman to achieve pregnancy. The herbicide atrazine has been associated with cycle irregularity and long follicular phases. Pyrethroids are a pesticide associated with lower levels of anti-müllerian hormone (AMH). AMH is produced by growing follicles and is thus a marker of ovarian reserve.

Discussion

Since BPA, phthalates, and pesticides are so prevalent in the environment, it is nearly impossible to eliminate exposure, which makes this an essential topic to address in the field of women’s health and fertility awareness. Given the ample evidence that these contaminants do affect reproductive health, it is surprising this isn’t discussed more widely. In the seven years since Chieng et al published their article, one would hope strides have been made to reduce the manufacture of these contaminants.

“Since BPA, phthalates, and pesticides are so prevalent in the environment, it is nearly impossible to eliminate exposure, which makes this an essential topic to address in the field of women’s health and fertility awareness.”

Even if people limit their exposure to these contaminants by changing their household or personal care products or eating organic foods, some baseline environmental exposure will remain (e.g., organochlorine pesticides persist in the environment). It would be useful to know if other endocrine disruptors bioaccumulate as well. If these contaminants persist and there isn’t a way to properly eliminate them, that could have drastic reproductive health implications. A retrospective analysis could help determine whether introduction of these contaminants correlates with the declining fertility rates. It would also be interesting to study how much exposure is strictly from the ambient environment versus household/personal care/food products, since environmental exposure is hardest to control. Further research on this topic is certainly necessary, and more drastic action is needed to ban these contaminants from use.

The impact of environmental contaminant exposures on fertility should be a global concern. All consumers should be aware of the harmful nature of these contaminants found in everyday products. As a future physician, I plan to educate my patients on the need to limit their exposure to these endocrine disruptors.

References

[1] Chiang, C., Mahalingam, S., & Flaws, J. A. (2017). Environmental Contaminants Affecting Fertility and Somatic Health. Seminars in Reproductive Medicine, 35(3), 241–249. doi: 10.1055/s-0037-1603569.

ABOUT THE AUTHOR

Ryan Powley

Ryan Powley is a fourth-year medical student at Liberty University College of Osteopathic Medicine in Lynchburg, VA. She completed her undergraduate education at Grove City College in Grove City, PA and plans to pursue residency in family medicine. She is interested in women’s health and behavioral health. Powley enrolled in the FACTS elective to gain a better understanding of natural family planning options so she could counsel her patients on all the methods available to them. She hopes to empower her female patients to take control of their reproductive health.