Could environmental pollution from industry contribute to cryptorchidism?

Environmental pollution from industries such as coal mining and metalworking may play a role in the growing numbers of unborn testicle-born boys, according to a study published today ( Wednesday) in Human Reproduction [1].

The researchers assert that their findings generate hypotheses, cannot demonstrate that these industries cause cryptorchidism and that more targeted research is needed. However, a survey of nearly 90,000 boys was the first to report at a national level a recent increase in the frequency of the condition over time and to identify records of cases in previous parts of France. in the fields of mining or metalworking, such as the Pas de Calais in northern France. All boys worked to correct untested testicles between 2002 and 2014 when they were younger than seven years.

Cryptorchidism is the absence from the scrotum of one or both testes around the time of birth. It is the most common male genetic defect, occurring in between one and eight percent of infants. In most cases, the condition corrects itself within six months of birth, but about one in 100 boys still has testicles that remain undiagnosed. When this happens, surgery is needed to move them to the right position and this is done happily before the age of one. Boys with untreated cryptorchidism may have fertility problems later in life and are at an increased risk of testicular cancer.

Other research has shown that some chemicals, such as phthalates and toxins, are linked to cryptorchidism. In the current study, the researchers decided to study trends over time and in areas of metropolitan France to see if the local geographical environment is an important driver for the deficit.

Dr. Joëlle Le Moal, medical epidemiologist at the DATA Department of Science, Santé publique France (French Public Health France), and her colleagues identified 89,382 cases of operative cryptorchidism between 2002 and 2014 from public records; they found that the frequency of the situation increased by 36% during this period.

They used a disease mapping model to report the risk of cryptorchidism according to a postcode, and identified 24 clusters scattered across France except in the southwest. The gatherings were mainly in the north and central east of France, with the main group around the city of Lens in the Pas de Calais, formerly a coal mining district. Here, the risk of a single unstable testis increased by more than half and the risk of two incontinent testes (bilateral cryptorchidism) was more than five times the national average. There were 1,244 cases and the researchers estimated that this was more than 453 cases above the expected number in the area.

The researchers write that this area “includes the two former production sites of a smelter. … where the majority of the local population was employed After more than a century of non – ferrous metal production, it closed in 2003 and encouraged widespread environmental pollution, with metals, especially lead and cadmium. This collection also includes a metabolic plant. , and two business areas still in operation “.

The researchers monitored mining activity in eight of the 24 groups, metallurgic activity in 17 and mechanistic activity in 16. They also found clusters of bilateral cryptorchidism cases in some agricultural areas where there are orchards and vineyards, which can be plucked by poisons.

Dr Le Moal said: “Our main findings are the increase in the frequency of operative cryptorchidism in France during the study period, and the strong tendency for cases to converge in specific locations. ‘such a discovery was first recorded at the country level for this birth defect.Our findings suggest that the geographic environment may contribute to the accumulation of cryptorchidism and interactions with socioeconomic factors. The industrial activities identified in the collections could be a source of persistent environmental pollution with metals, dioxins and polychlorinated biphenyls, known as PCBs. -oxygen in cryptorchidism and other testicular problems with hormonal disturbances. ”

Low socioeconomic status is an established risk factor for cryptorchidism and several of the clusters identified in the study were in areas where economic activity was declining with business closures. Other factors associated with an increased risk of cryptorchidism include maternal smoking and premature or premature birth for gestational age, all of which are known to be more common in industrial areas and in association to low socio-economic status.

Dr Le Moal said: “We have made a number of observations that need to be substantiated in further research. Our study is interesting and new because we used a large, national sample that allowed us to consider geographically observable observations. However, these results do not need to be misinterpreted.The potential pollutants we have identified may be symptoms associated with other chemicals.Moreover, we do not know for sure how that the people may be defiled. “

The methods used in the study may have underestimated a health problem because it reveals cases of surgery-corrected cryptorchidism. Other limitations include that surgical practices may evolve and there may be local differences.

In accompanying statement [2], Professor Richard Sharpe, of the Medical Research Council ‘s (MRC) Center for Regenerative Health at the University of Edinburgh, UK, writes that this is a “landmark study” and, in ‘identifies 24 “hotspot collections” of cryptorchidism cases scattered across France, it “confirms an important role for environmental factors in determining the risk of cryptorchidism”.

He continues: “What sets this study apart is its national scale, and, as a result, its ability to paint a picture of the risk of a male child having persistent cryptorchidism (ie need on surgical correction) according to where in France he was born / spent his early life; indicating an increase in cases of cryptorchidism over the short term of the study is shouting at the cake, albeit a bit scary. “

He writes that the study is important for four reasons. “First, it uses the most advanced spatial analysis statistical methods so it is at a technical front-end level. Second, it uses data for an entire country over a 13-year period. Third, it provides strong supporting evidence that environmental (maternal) effects on the male fetus are a real health risk today, even in a modern developed country such as France. Fourth, and in my opinion the most important, it is suggest that our recent research will focus on environmental chemicals as a potential source of cryptorchidism (and other possible growing male reproductive disorders) right in principle but wrong in practice the main focus of research in this area over the 20+ years has been on chemicals to which the majority of the population is exposed to low fat foods (eg bisp henol A, phthalates, poisons modern day) than those that are more closely associated with close industry.

“Lastly, and most importantly, the study by Le Moal et al .. is a strong reminder that many cases of cryptorchidism can be prevented, if only we can identify the industrial chemical cultures, a plausible idea. to relate generally to the most common. male reproductive disorders. At an age where twin fertility problems are on the rise, this is another wake – up call for all of us. “

###

[1] “Time and spatial trends of operational cryptorchidism in France and environmental considerations: a national study from 2002 to 2014”, by J. La Moal et al. Human Reproduction iris. doi: 10.1093 / humrep / deaa378

[2] “Position, Position, Position – where you are born may determine your reproductive health (and more generally)”, by Richard Sharpe. Human Reproduction iris. doi: 10.1093 / humrep / deab051