Human exposure to endocrine disrupting chemicals and male fertility

Are EDCs responsible for downward trends in male fertility?

A growing body of evidence suggests that endocrine-disrupting compounds (EDCs) are contributing to declines in fertility. This case-control study found that EDCs were associated with changes to sex hormones and risk of subfertility in men. The researchers say environmental levels of these chemicals should be reduced to protect male fertility.

Abstract

Human exposure to endocrine disrupting chemicals and fertility: A case–control study in male subfertility patients, ScienceDirect, Environment International, Volume 84, November 2015, Pages 154–160.
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Background
Dioxins, PCBs, chlorinated pesticides, brominated flame retardants, bisphenol A, triclosan, perfluorinated compounds and phthalates are known as endocrine disrupting chemicals (EDCs).

Objectives
The aim of our study was to investigate whether higher exposure to EDCs is associated with increased subfertility in men.

Methods
We measured biomarkers of exposure in 163 men, recruited through four fertility clinics. According to WHO guidelines, we used a total motility count (TMC) of 20 million as cut-off value. We assigned patients to the case group when two semen samples – collected at least one week apart – had a TMC < 20 and to the control group when both samples had a TMC ≥ 20. To estimate the risk of subfertility and alteration in sex hormone concentrations we used multivariable-adjusted analysis, using logistic and linear regressions, respectively.

Results
For an IQR increase in serum oxychlordane, the odds ratio for subfertility was 1.98 (95% CI: 1.07; 3.69). Furthermore, men with serum levels of BDE209 above the quantification limit had an odds of 7.22 (1.03; 50.6) for subfertility compared with those having values below the LOQ. Urinary levels of phthalates and triclosan were negatively associated with inhibin B and positively with LH. Urinary bisphenol A correlated negatively with testosterone levels.

Conclusions
Our study in men showed that internal body concentrations of endocrine disrupting chemicals are associated with an increased risk of subfertility together with alterations in hormone levels. The results emphasize the importance to reduce chemicals in the environment in order to safeguard male fertility.

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