Wednesday March 17, 2021, 12:05 AM Laboratory coats Credit: PA Archive/PA Images Environmental pollution from industries such as coal mining and metal works may play a role in the increasing numbers of boys born with undescended testicles, new research suggests. Researchers say their findings are hypothesis-generating, cannot show that these industries cause the condition called cryptorchidism and that further, targeted research is required. However, the study of nearly 90,000 boys is the first to describe at a national level a recent increase in incidence of the condition over time. It also identified clusters of cases in parts of France that are former mining or metal-working areas, such as the Pas de Calais in northern France.