Environmental pollution from industries such as coal mining and metal works may play a role in the increasing number of boys born with undescended testicles, a new study warns.
Undescended testicles, also known as cryptorchidism, is the most common male genital defect, affecting between 1% and 8% of newborns. In the U.S., about 200,000 boys are born with the condition each year.
The study focuses on 89,382 French boys who went under the knife for cryptorchidism between 2002 and 2014. Results show the number of children with an undescended testicle increased by 36%.
Using a disease mapping model and data on the patients’ home addresses, the researchers identified 24 clusters scattered across France. Most of the clusters were located in the north or central eastern parts of the country. But the largest concentration was around the city of Lens in the Pas de Calais, a former coal mining area.
In Lens, the risk of having one undescended testicle increased by more than 50% compared to national levels. Likewise, cases where both testicles were in the wrong place, known as bilateral cryptorchidism, shot up five-fold, the researchers found. In total, 1,244 boys were diagnosed with the condition, 453 cases above the expected number for the area.
Other factors may be responsible for the increasing number of boys being born with undescended testicles in these places, however. Low economic status, a well-known risk factor, could play a part given several of the clusters were in areas where economic activity has declined over the past few years.
Fortunately, Cryptorchidism usually corrects itself within three to six months, however, one in 100 boys’ testicles remain undescended.
Surgery is then required to move the testicles into the correct position, ideally before the boy turns one. Untreated cryptorchidism has been linked to infertility and a higher risk of testicular cancer in later life.
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The findings revealed that parts of France that had a history of mining or metalworking had increased incidences of cryptorchidism. Previously, research has indicated that some pesticides and phthalates (a chemical used to increase the flexibility of plastics) can also lead to cryptorchidism.
The research team proudly confirmed that they detected a correlation between pollution and cryptorchidism but that more work needed to be done to establish a cause-and-effect relationship.
“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,” said paper author Joëlle Le Moal. “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 research had a breakthrough when the team was able to find geographic links among the cases.
“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 of playing a role in cryptorchidism and other testicular problems by disrupting hormones.”
The researchers said that the Pas de Calais area “includes the two production sites of a former smelter where most of the local population was previously employed. After more than a century of non-ferrous metal production, it closed in 2003 and induced widespread environmental pollution with metals, especially lead and cadmium. This cluster also includes a metallurgic plant and two industrial areas still in activity.”