Fertility Centers of Illinois physicians and staff continue to keep you up-to-date on advances in reproductive medicine and the availability of the newest technologies for your patients. This letter addresses the latest information on environmental exposures and fertility.

Patients are increasingly inquiring about ways to improve and optimize fertility. The question of the role of one’s environment is an increasing concern among many patients. Chemical and environmental toxins are ubiquitous in the environment. It is estimated women are exposed to at least 43 chemicals during pregnancy. During pregnancy, chemicals can cross the placental border and lead to prenatal exposure and subsequent disease. Prior to pregnancy, there are a group of chemicals: heavy metals, such as mercury, lead, and cadmium, pesticides, endocrine-disrupting chemicals (EDCs), that can lead to issues of infertility. Air pollution also remains a concern. We will review the implications of exposures to these agents and potential mechanisms to minimize risk. 

HEAVY METALS

Mercury leaches into the water as an industrial by-product. It can also be found in face lotions created outside the US and mercury thermometers. Mercury is a neurotoxin and has been linked to low IQ and poor language and motor development. There are fish that are known to have high mercury levels including king mackerel, shark, swordfish, marlin, orange roughy, and bigeye tuna, which should be avoided in pregnant and breastfeeding women and limited in women attempting to conceive. It is recommended to have 1-2 serving of fish lower in mercury weekly; such as salmon and shrimp. It is recommended to screen exposure risk for mercury and counsel regarding avoidance of high-mercury fish.

Lead is found in old homes and those renovating an old home. It can also be found in traditional remedies, jewelry, imported pottery, and pica. Elevated serum lead is a neurotoxin and linked to pregnancy-induced hypertension and miscarriage. Patients should be screened for lead exposure and then counseled accordingly.

Cadmium is found in rechargeable batteries, plastic production, organ meats, paint pigment, tobacco smoke and pesticides on produce. Elevated levels can lead to placental epigenetic modifications, emotional issues in boys, low birth weight, and smaller head circumference in children. Post pubertal men, cadmium is linked to decreased sperm quality, motility, and testosterone levels. In women, cadmium can mimic/inhibit endogenous estrogen levels leading to irregular cycles. It is recommended to screen patients for exposure and counsel to avoid tobacco exposure, organ meats and choosing organic grains and root vegetables when possible.

The Study of Metals in Assisted Reproductive Technologies (SMART), a prospective cohort study of infertile couples assessed whether preconception exposure to lead, mercury, and cadmium affects in vitro fertilization (IVF) outcomes. The researchers found that increased cadmium levels were associated with decreased oocyte fertilization and decreased implantation rates.  This research highlights the need to inform patients of environmental exposures and arguably to convince the government to increase the regulation of toxic substances.

PESTICIDES

Pesticides are ubiquitous in our environment with an estimated 90% of the population having detectable levels in serum and urine samples. Pesticides can persist in the environment slowly degrading and contaminating our food, water, air, dust, and soil. Preconception and pregnancy pesticide exposure has been linked to intrauterine growth reduction, decreased IQ, pregnancy loss and low birth weight. Pregnancy and preconception pesticide exposure has also been linked to higher levels of leukemia, testicular cancer in children. It is important to counsel patients to avoid pesticides and insecticides in the home and on pets. Those that work in agriculture need to wash hands after work, appropriate protective gear and remove shoes prior to coming into the home. It is important to try and consume organics produce in particular for the following items: grapes, plums, peaches, string beans, potatoes, kale, strawberries, apples, pears, spinach, celery, and peppers (www.ewg.org/foodnews/dirty-dozen.php)

ENDOCRINE DISRUPTORS

Endocrine-disrupting chemicals can mimic or block endogenous hormone production and lead to adverse reproductive outcomes. The three main ones are bisphenol A (BPA), phthalates, and

Polybrominated diethyl ethers (PBDEs). BPA is found in plastics, metal can liners, cash register receipts, computers, cell phones, and reusable food containers. BPA exposure can occur from inhalation, ingestion and skin absorption. BPA is linked to aberrations in oocyte quality, embryo development, euploidy rate, and placentation. Concerns around BPA have led to “BPA-free” plastics, which often use bisphenol S an equally harmful compound. It is advised to educate patient about limiting their use of plastic containers, especially reheating in microwaves and advise switching from plastic containers to glass and stainless steel,  avoid taking cash registers receipts printed on thermal paper, avoid canned foods and bottled water with the number 3 or 7 stamped on the bottom.

Phthalates are synthetic compounds found in toys, food processing, IV tubing, body lotions, and floor processors. They have been linked to an early gestational age of delivery. A study exploring environmental exposures on IVF outcomes suggested that phthalates lower the number of oocytes retrieved, pregnancy rates and increased risk of loss of fewer than 20 weeks. Paternal exposure has been linked to higher levels of sperm DNA damage. Couples should be advised to replace plastic with glass or steel for cooking and drinking, minimize heating foods in plastic and minimize fast/processed foods.

PBDEs are flame retardants used on upholstered furniture, textiles, carpeting, and electronics, in the US mostly now replaced with replacement flame retardant alternatives. Due to their lipophilic nature, they have a half-life of up to 12 years. In California where flame retardants are more often used, exposure in pregnancy has been linked to maternal thyroid abnormalities. Other studies have suggested an increased incidence of pregnancy loss of 28% in patients with higher levels of PBDEs in the preconception period. Similarly, higher levels in children during neurodevelopment period have been linked to lower IQ/decreased attention in children. It is important to inquire about occupational exposure to these chemicals, advice those trying to conceive to avoid exposure and purchase furniture not using PBDEs, minimize children exposure to newly upholstered furniture with PBDEs, and lastly advise taking off shoes and washing hands for those that may have exposure outside of the home.

AIR POLLUTION

Epidemiologic studies have suggested a relationship between air pollution and adverse pregnancy outcomes: early pregnancy loss, stillbirth, preterm delivery, and low birth weight.  A longitudinal study of environmental exposures and fertility also demonstrated a relationship of air pollution to pregnancy loss. In addition to obstetrical outcomes, there has been a relationship between poor air quality to lower IQ in children. A study exploring the impact of living near a highway showed higher rates of infertility. Although difficult to control the environment, it is advised to avoid outdoors during the time of poor air quality and to use a HEPA filter in the home.

Downloadable Information for patients can be found at the Program on Reproductive Health and the Environment and the Centers for Disease Control and Prevention.

The physicians of Fertility Centers of Illinois are happy to answer any questions regarding this topic and others in our series from you, your staff or your patients. 

REFERENCES

  1. Bloom MS, Parsons PJ, Steuerwald AJ, Schisterman EF, Browne RW, Kim K, et al. Toxic trace metals and human oocytes during in vitro fertilization (IVF). Exposure to environmental agents. ACOG Committee Opinion No 575. Obstet Gynecol 201 Reprod Toxicol 2010; 29:298–305.
  2. Bloom MS, Fujimoto VY, Steuerwald AJ, Cheng G, Browne RW, Parsons PJ. Background exposure to toxic metals in women adversely influences pregnancy during in vitro fertilization (IVF). Reprod Toxicol 2012; 34:471–81.
  3. Thalia R. Segal, M.D. and Linda C. Giudice, M.D., Ph.D. Before the beginning: environmental exposures and reproductive and obstetrical outcomes  Fertil Steril_ 2019;112:613–21
  4. Rochester JR, Bolden AL. Bisphenol S and F: a systematic review and comparison of the hormonal activity of bisphenol-a substitutes. Environ Health Perspect 2015; 123:643–50.
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  6. Yang S, Tan Y, Mei H, Wang F, Li N, Zhao J, et al. Ambient air pollution the risk of stillbirth: a prospective birth cohort study in Wuhan, China. Int J Hyg Environ Health 2018; 221:502–9.
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