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Study Reveals Mens Sperm Count Decreases If Mums Were Exposed To Pesticides And Heavy Metals

A study by the University of Geneva in Switzerland has revealed that adult men can experience poor semen quality if their mothers were exposed to pesticides and heavy metals during pregnancy.

Scientists from the University of Geneva (UNIGE) in Switzerland and the Research Institute for Environmental and Occupational Health (IRSET) from the city of Rennes in north-western France have established a link between low fertility in men and their mothers’ occupational exposure to heavy metals and pesticides – also known as endocrine disruptors – during pregnancy.

Endocrine disruptors 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, according to the World Health Organization (WHO).

University of Geneva, Serge Nef/Real Press

These can include certain pesticides, heavy metals, and phthalates, which are a group of chemicals used to make plastics more durable.

Recently, a growing number of studies have shown that environmental factors and lifestyle habits of pregnant women play an important role in the health of their child.

In addition, another study from the University of Geneva two years ago showed that only 38 percent of Swiss men had semen parameters above the WHO recommended threshold.

The current results obtained through the UNIGE-IRSET collaboration showed that men who have been exposed to products which contain endocrine disruptors while in uterus, are twice more likely to have semen volume and total sperm count per ejaculation below the values set by the WHO.

University of Geneva, Marion Istvan/Real Press

Ronan Garlantezec, a researcher at IRSET, the Rennes University Hospital Centre (CHU), and the University of Rennes 1, explained: “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 sperm production and semen quality in adulthood.”

He continued: “In view of the results obtained by Serge Nef’s team on the semen quality of Swiss men, we 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.”

Serge Nef, professor at the Department of Genetic Medicine and Development of the UNIGE Faculty of Medicine, and his team evaluated semen quality of around 3,000 study participants, out of which 1,045 had mothers who worked during pregnancy.

Nef explained: “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.

University of Geneva, Serge Nef/Real Press

“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 participants’ pregnancy period.”

IRSET research director Luc Multigner explained that this allowed analysis of semen parameters of men whose mothers were employed during pregnancy to be conducted.

He added: “The maternal jobs were classified according to the International Classifications of Occupations (ISCO-88 of the International Labour Office of the WHO).”

According to Multigner, the analysis helped epidemiologists establish probabilities of exposure to one or more categories of substances that may contain endocrine disruptors according to the mothers’ occupation.

He said: “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.”

University of Geneva, Ronan Garlantezec/Real Press

According to Garlantezec, the results of the study revealed that young men exposed to hazardous chemical substances while in uterus are twice as likely to have values below the reference values established by the WHO, both in terms of semen volume (threshold at 2 ml) and the total number of spermatozoa per ejaculation (40 million).

He explained which substances the study focused on by saying: “In our study, the products most associated with these anomalies were pesticides, phthalates, and heavy metals.”

Serge Nef emphasised: “These observations do not determine the future fertility of young men and only a follow-up [study] over time will make it possible to assess the consequences.

“Nevertheless the results could explain at least partially the low semen quality of some young Swiss men.”

The team has already planned another study with the same participants to research the link between maternal occupational exposure to endocrine disruptors and changes in sexual hormones during adulthood.

Ronan Garlantezec said: “It would be interesting to carry out a similar study in women to evaluate whether the impact of endocrine disruptors is the same on the female reproductive system”, although he admitted it would be more complex to carry out such research.

University of Geneva, Luc Multigner/Real Press

Since the analysed data concerns women which became mothers 25 years ago, scientists believe the professions exerted by women have greatly evolved like the presence of endocrine disruptors in the products used.

Nef added: “Hence the crucial preventive role of this study.”

The results were published in the journal Human Reproduction.

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