Reproductive biologists aren’t so sure. Patricia Hunt of Washington State University was alerted to possible dangers of BPA in 1999 when her mouse study on an unrelated topic suddenly went haywire, with dozens of female mice unexpectedly developing chromosomal abnormalities in the eggs they carried in their ovaries. As it turned out, a lab worker had used a detergent that caused BPA to leach out of the animals’ plastic cages.

Phthalates have also raised concern. The compounds are used to soften the plastics in products ranging from rubber duckies and vinyl shower curtains to medical tubing and IV bags. They are also found in hundreds of personal-care products, including fragrances, body lotions, nail polishes and shampoos. Again, 30 years of data from institutions like the NIH and EPA point to potential problems in animals stemming from prenatal exposure, including abnormalities in the reproductive tract and a decline of sperm quality. Now there is a smattering of human studies, too. In 2006 Danish researchers found that higher levels of a phthalate in mothers’ breast milk correlated with lower testosterone in male babies at 1 to 3 months of age. Similarly, Dr Russ Hauser at Harvard studied roughly 500 men at a fertility clinic and found that those with higher levels of certain phthalates in their urine had lower sperm counts and sperm motility.

Finally there are the flame retardants, PBDEs. They turn up in fabrics, upholstery, foam mattresses, circuit boards and the casings of computers and televisions—and apparently escape into indoor air and dust. Animal studies show they can have negative impacts on learning and memory, sperm counts and thyroid functioning in rats and mice. PBDEs tend to linger a long time in the body, and one mixture in particular seems “quite biologically active, especially during development, as we’ve seen in studies on rats, mice and fish,” says Linda Birnbaum, director of experimental toxicology at the EPA.

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