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Boys living near coal mining areas suffer higher levels of undescended testes, study finds

Researchers in France have found higher incidences of people living with cryptorchidism, commonly known as undescended testes, when they live near coal mining areas.

A French study assessed incidences of operated cryptorchidism from 2002 to 2014 and found a cluster of cases localised in a former coal mining and metallurgic area in northern France, currently an industrial area.

The industrial activities identified in the clusters are potentially the source of persistent environmental pollution by metals, dioxins and polychlorinated biphenyls, which are oily chemicals that do not appear naturally.

Cryptorchidism is the absence of one or both testes from the scrotum at birth or after birth and is the most frequent male genital defect among infants. Around one in every 25 boys in the UK and three per cent in the US are born with the condition.

In most cases, the condition corrects itself within six months of birth, but approximately one in 100 boys have testicles that remain undescended, and this requires surgery to move them into the right position.

The study suggests that the risk of having one undescended testis increased by more than a half in children within the mining community area and the risk of both testes being undescended increased more than five-fold when compared to the national level.

The study population was composed of 89,382 new cases of operated cases of cryptorchidism in boys under the age of 7 years and is the first to describe at a national level a recent increase in incidence of the condition over time.

Dr Joelle Le Moal, a medical epidemiologist at the DATA Science Department, Public Health France, said: “Our main findings are the increase in the frequency of operated cryptorchidism in France during the study period, and the strong tendency for cases to cluster together in particular locations.

“This is the first time that such a finding has been documented at a country level for this birth defect.

“Our results suggest that the geographical environment could contribute to the clustering of cryptorchidism and interact with socio-economic factors.

“The industrial activities identified in the clusters are potentially the source of persistent environmental pollution by metals, dioxins and polychlorinated biphenyls, known as PCBs.

“PCBs, pesticides and dioxins are suspected to play a role in cryptorchidism and other testicular problems by disrupting hormones.”

Rod Mitchell, professor of developmental endocrinology, MRC Centre for Reproductive Health, University of Edinburgh, said: “Cryptorchidism is associated with several other male reproductive disorders including testicular cancer and infertility, which may result from reduced testosterone in males during foetal life.

“Therefore, these findings may also have implications for the current decline in male reproductive health in general.

“We have a moral duty to identify and eliminate the factors that are behind the recent increase in the incidence of male reproductive disorders.”

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