Clinical Review

2020 Update on fertility

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References

Environmental toxicants: The hidden danger

Segal TR, Giudice LC. Before the beginning: environmental exposures and reproductive and obstetrical outcomes. Fertil Steril. 2019;112:613-621.

We receive news daily about the existential risk to humans of climate change. However, a risk that is likely as serious goes almost unseen by the public and most health care providers. That risk is environmental toxicants.8

More than 80,000 chemicals are registered in the United States, most in the last 75 years. These chemicals are ubiquitous. All of us are continuously exposed to and suffused with these toxicants and their metabolites. Air pollution adds insult to injury. Since this exposure has especially significant implications for fertility, infertility, pregnancy, perinatal health, childhood development, adult diseases, and later generational reproduction, it is imperative that reproductive health professionals take responsibility for helping mitigate this environmental crisis.

The problem is exceptionally complicated

The risks posed by environmental toxicants are much less visible than those for climate change, so the public, policymakers, and providers are largely unaware or may even seem uncaring. Few health professionals have sufficient knowledge to deliver care in this area, know which questions to ask, or have adequate information/medical record tools to assist them in care—and what are the possible interventions?

Addressing risk posed by individual toxicants

Addressing the problem clinically requires asking patients questions about exposure and recommending interventions. Toxicant chemicals include the neurotoxin mercury, which can be addressed by limiting intake of fish, especially certain types.

Lead was used before 1978 in paint, it also was used in gas and in water pipes. People living in older homes may be exposed, as well as those in occupations exposed to lead. Others with lead exposure risk include immigrants from areas without lead regulations and people using pica- or lead-glazed pottery. Lead exposure has been associated with multiple pregnancy complications and permanently impaired intellectual development in children. If lead testing reveals high levels, chelation therapy can help.

Cadmium is a heavy metal used in rechargeable batteries, paint pigment, and plastic production. Exposure results from food intake, smoking, and second-hand smoke. Cadmium accumulates in the liver, kidneys, testes, ovaries, and placenta. Exposure causes itai-itai disease, which is characterized by osteomalacia and renal tubular dysfunction as well as epigenetic changes in placental DNA and damage to the reproductive system. Eating organic food and reducing industrial exposure to cadmium are preventive strategies.

Pesticides are ubiquitous, with 90% of the US population having detectable levels. Exposure during the preconception period can lead to intrauterine growth restriction, low birth weight, subsequent cancers, and other problems. Eating organic food can reduce risk, as can frequent hand washing when exposed to pesticides, using protective gear, and removing shoes in the home.

Endocrine-disrupting chemicals (EDCs) are chemicals that can mimic or block endogenous hormones, which leads to adverse health outcomes. In addition to heavy metals, 3 important EDCs are bisphenol A (BPA), phthalates, and polybrominated diethyl ethers (PBDEs). Exposure is ubiquitous from industrial food processing, personal care products, cosmetics, and dust. Phthalates and BPA have short half-lives of hours to days, while PBDEs can persist in adipose tissue for months. Abnormal urogenital and neurologic development and thyroid disruption can result. Eating organic food, eating at home, and decreasing processed food intake can reduce exposure.

BPA is used in plastics, canned food liners, cash register receipts, and epoxy resins. Exposure is through inhalation, ingestion, and dermal absorption and affects semen quality, fertilization, placentation, and early reproduction. Limiting the use of plastic containers, not microwaving food in plastic, and avoiding thermal paper cash register receipts can reduce exposure.

Phthalates are synthetically derived and used as plasticizers in personal and medical products. The major source of phthalate exposure is food; exposure causes sperm, egg, and DNA damage. Phthalate avoidance involves replacing plastic bottles with glass or stainless steel, avoiding reheating food in plastic containers, and choosing "fragrance free" products.

PBDEs are used in flame retardants on upholstery, textiles, carpeting, and some electronics. Most PBDEs have been replaced by alternatives; however, their half-life is up to 12 years. Complications caused by PBDEs include thyroid disruption, resulting in abnormal fetal brain development. Avoiding dust and furniture that contain PBDEs, as well as hand washing, reduces exposure risk.

Air pollutants are associated with adverse obstetric outcomes and lower cognitive function in children. Avoiding areas with heavy traffic, staying indoors when air is heavily polluted, and using a HEPA filter in the home can reduce chemicals from air pollution.

Recommendations

The magnitude of the problem that environmental toxicant exposure creates requires health care providers to take action. The table in the publication by Segal and Giudice can be used as a tool that patients can answer first themselves before review by their provider.2 It can be added to your electronic health record and/or patient portal. Even making general comments to raise awareness, asking questions regarding exposure, and making recommendations can be helpful (TABLES 1 and 2). When possible, we also should advocate for public awareness and policy changes that address this significant health issue.

WHAT THIS EVIDENCE MEANS FOR PRACTICE
Environmental toxicants are a significant health problem that can be effectively mitigated through patient questions and recommended interventions.

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