Conceiving of a Healthier Future: Toxics, Pregnancy and Male Fertility Outcomes
February 26, 2014
The misconception remains that infertility is primarily a woman’s problem. In fact, the Center for Disease Control and Prevention’s statistics on infertility rates only reference married women. Perhaps this bias lingers because biologically, males cannot become pregnant, or because of the normative gender roles our culture [i] attaches to the function and capabilities of eggs and sperm.
Whatever the reason, our focus on female infertility is masking the reality of the issue. More than half of cases of infertility result[ii] from a male partner's condition. Based on semen quality analysis – a common marker of male fertility – the percentage of men whose sperm count has fallen below the level associated with optimal fertility has increased[iii] in recent years. A 2012 study[iv] of more than 26,000 French men found that the sperm count of the average French man fell by 32.2 percent between 1989 and 2005. At the same time, the proportion of properly formed sperm also fell from 60.9 percent to 52.8 percent.
While the causes of male infertility are complex and multi-faceted, a growing body of research indicates chemicals commonly found in our everyday environment – at home, at work, and in the very air we breathe – are taking a toll on male fertility.
Exposure to toxic chemicals can impact the male reproductive system before, during, and after a pregnancy.
Preconception care is a growing focus for many healthcare providers. But like fertility in general, preconception care often focuses on the health of a woman. However, a 2012 study of couples seeking to become pregnant found that exposure to persistent chemicals such as pesticides, flame retardants (PBDEs) and perfluorinated compounds (used to repel stains and water) may adversely affect a couple’s fecundity, measured as time to pregnancy.
More intriguing, the study[v] found that the chemicals associated with reduced couple fecundity differed between males and females, but with a larger number of associations observed for males.
We know that exposure to chemicals during pregnancy is also critical. Extensive animal and human studies show that exposure during fetal development can lead to[vi] malformations of the male reproductive tract such as hypospadias, undescended testes, testicular dysgenesis syndrome, and altered prostate development, breast development, testis size, and puberty onset. Particular attention is being paid to endocrine disrupting chemicals, which disrupt the production or function of hormones during critical windows of development. Even minor exposures can have lifelong consequences. Often at low levels of exposure, endocrine disruptors can have a wide range of health effects[vii], including but not limited to infertility. In animal and some human studies, fetal exposure to DDE, DDT, vinclozolin, PCBs, bisphenol A, phthalates, and DES affected male genital tract development and function.
Perhaps one of the most intriguing findings of recent research is that damage from exposures to some chemicals can be passed to subsequent generations. For instance, in one study, exposure to the chemical DES during pregnancy was associated with[viii] genital malformation in the grandsons of women exposed. Likewise, both lead and vinclozolin (a pesticide) can have transgenerational impacts[ix].
Although exposure to toxic chemicals is ubiquitous, minority populations are more likely to live in the counties with the highest levels of outdoor air pollution[x] and to be exposed to a variety of indoor pollutants[xi], including lead, allergens, and pesticides than white populations. Furthermore, low-wage immigrant populations disproportionately work[xii] in occupations associated with a hazardous workplace environment.
Given the growing evidence of the impact of chemicals on fertility and prenatal development, why does the situation persist? Unfortunately, the law that regulates today’s chemicals is more than 30 years old, and does not protect our families from the dangers of chemical exposure. An estimated 7,000 chemicals come to the market every year, but because of deficiencies in the current regulatory structure, most environmental chemicals, unlike pharmaceuticals, enter the marketplace without comprehensive and standardized information regarding their reproductive or other long-term toxic effects.
Reform is desperately needed to ensure that chemicals are proven to be safe before they end up in our homes, schools, and workplaces.
Thanks in part to a growing awareness of the impact of toxic exposure during pregnancy, women are increasingly advised to avoid or limit exposure to certain chemicals. This is an important starting point, but we must continue to explore the effect of toxic chemicals on male fertility, while simultaneously reforming our chemical regulation laws.