Scientists analyzed the potential impact of endocrine disruptors on semen quality of men whose mothers were working at the early stages of their pregnancy. Their results show that men who have been exposed in utero to products known to contain endocrine disrupting chemicals (Phthalates and pesticides in particular) are twice more likely to have semen volume and total sperm count per ejaculation below the reference values set by the World Health Organization (WHO).
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Backstory
According to the World Health Organization (WHO), endocrine disrupters are chemical substances of natural or synthetic origin which can interfere with the endocrine system and cause adverse health effects in an organism, or its progeny.
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“Several animal studies have already shown that gestational exposure to certain endocrine disruptors can influence the development of the male reproductive system, as well as the sperm production and semen quality in adulthood.”
-Dr. Ronan Garlantézec, researcher at the IRSET, the Rennes University Hospital Centre (CHU) and University of Rennes 1.
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Study overview
The researchers were interested in studying the potential effect of exposure to endocrine disruptors during pregnancy as one out of many possible reasons behind the observed trends of lowered sperm count and quality reported in industrialized countries. The research team evaluated semen quality of around 3000 conscripts, 1045 out of which had their mother working during pregnancy.
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“For each of them, a semen quality analysis was carried out to determine the semen volume, as well as the sperm concentration, motility and morphology. A detailed questionnaire was also sent to the parents before the semen analysis was carried out, covering in particular the maternal jobs exerted during the conscripts’ pregnancy period.”
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This allowed for the analysis of semen parameters of men whose mothers were employed during their pregnancy. “The maternal jobs were classified according to the International Classification of Occupations (ISCO-88 of the International Labour Office of the WHO),” explains Luc Multigner, research director at the IRSET. “Exposure to products containing endocrine disruptors during pregnancy has been defined using a job-exposure matrix, which makes it possible to attribute the maternal exposure a probability score.” This has enabled epidemiologists to establish probabilities of exposure to one or more categories of products that may contain endocrine disruptors according to the mother’s occupation.
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Study results
Endocrine disruptors associated with poorer sperm quality
The results of this study show that young men exposed in utero to endocrine disrupting chemicals are twice as likely to have values below the reference values established by the WHO, both in terms of the semen volume (threshold at 2 ml) and the total number of spermatozoa per ejaculation (40 million). In this study, the products most associated with these anomalies were pesticides, phthalates and heavy metals.
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Preventing exposure to endocrine disrupting chemicals: What should people do?
The results of this study suggest an association between the mother’s occupational exposure to endocrine disruptors and a decrease in several semen parameters in their children during adulthood. “It therefore appears necessary to inform women planning to conceive and during their early stages of pregnancy of the potential hazards of exposure to these substances, which could alter their children’s fertility,” warns Dr. Luc Multigner.
Journal Reference: M Istvan, R Rahban, B Dananche, A Senn, E Stettler, L Multigner, S Nef, R Garlantézec. Maternal occupational exposure to endocrine-disrupting chemicals during pregnancy and semen parameters in adulthood: results of a nationwide cross-sectional study among Swiss conscripts. Human Reproduction, 2021; DOI: 10.1093/humrep/deab034
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