Most of the attention on phthalates, a group of hormone-disrupting chemicals found in PVC plastics, has been on fetal and child health, particularly regarding genital and behavioral development, such as incomplete virilization in infant boys and reduced masculine play as they grow up, and for girls, an earlier onset of puberty, but what about affecting hormonal function in adults?
Men exposed to high levels of phthalate had lower testosterone levels, but that was for workers in a plastics plant. In the general population, the evidence is mixed. A study in Sweden of men in their 20’s found no effect on testosterone, whereas a U.S. study on men in their 30’s did, at levels of exposure much lower than those factory workers. When there’s conflicting evidence like this, ideally we’d put it to the test, but you can’t ethically expose people; so, scientists have come up with convoluted methods like implanting the testicles from human fetuses into mice to keep them growing, but we want to know about the effects on adult testicles, which are harder to procure…until now. Consent was obtained from all the donors. Now, I’ve heard of blood donors, but this is a whole other level. No, they obtained the testicles from prostate cancer patients who underwent castration to control their disease. And indeed, they were able to get direct evidence that phthalates can inhibit testosterone production at the kinds of levels one sees in general population studies….