Testosterone and other male hormones affect not only the genitalia but the brain as well. In a curious study published in November in the International Journal of Andrology, U.S. researcher Shanna Swan measured young boys' tendencies toward traditional "male" play. Those boys who played the least with toy guns were exposed to the highest uterine levels of phthalates, as measured earlier in their pregnant moms' urine. Though no one knows what this might mean for the boys' future behavior, SWAN says such data suggest that "prenatal exposure to pthatlates, even at low environmental levels, can induce profound and permanent changes" in the brain and reproductive organs.
Not every expert buys the argument that it is pollutants that are messing with male hormones. It's a difficult hypothesis to prove in humans, even though the evidence is quite strong in animal studies. Dr. Michael Joffe at Imperial College, London, points out that testicular cancer cases mysteriously started rising in the mid 19th century. The timing means that victims of the disease would have been in the womb before many chemicals became widespread.
Still, it's enough to make a mom wonder about using phthalate-laden perfumes and creams during pregnancy. While we wait for more research on this side of the pond, the Danes have already put in place some of the strongest regulations on chemicals in the world, banning PFOA, phthalates, and a host of other compounds. They'll be keeping a keen eye on how things develop. Or don't.