A study in the International Journal of Andrology reports that adolescent boys with an extensive history of indoor swimming were about 3 times more likely to have lower testosterone levels.
The researchers working hypothesis is that the disinfectant by-products (DBPs) from more-chlorinated indoor pools are absorbed through the “highly permeable scrotum.” The DBPs then “might conceivably disrupt the blood-testes barrier and there by decrease the viability and number of Sertoli cells,” which help sperm cells develop.
Our view is that the weak statistical results (i.e., insignificant correlations or barely significant correlations with wide confidence intervals), speculative biological plausibility and findings of unknown clinical significance are insufficient bases on which to scare parents about indoor swimming pools.
But the real study killer here is that even the Princess of Environmental Estrogen Hysteria and Duchess of Low-Sperm Count Mania (i.e., Shanna Swan) dumped on the results in this Environmental Health Perspectives article:
Shanna Swan, a professor of preventive medicine at Mt. Sinai School of Medicine, finds the study intriguing but unconvincing due to factors such as the different hormone effects after swimming in indoor and outdoor pools, which tend to have roughly similar chlorination treatment. She also pointed to the paucity of evidence from other studies supporting the idea that the doses the boys received could do such damage, and she says effects from bath water exposures should have been considered. Bernard says those data weren’t available and that bath water likely is different from pool water due to the presence of fewer organics such as urine. But he agrees the variable is important and says it is something he plans to test in the future.
Rest assured chemophobes, you really are way out on a limb if Shanna Swan says so.