During the first few years of life, when babies' cells continue to undergo "programming," exposure to certain toxic chemicals can disrupt the delicate process. Bisphenol A, a compound in hard, clear polycarbonate plastics that mimics the effects of estrogen, has raised particular concern because it interferes with hormone levels and cell signaling systems. In August, several dozen scientists issued a review of 700 studies on BPA warning that the levels most people are exposed to put them at elevated risk of uterine fibroids, endometriosis, breast cancer, decreased sperm counts, and prostate cancer. Infants, the report said, are most vulnerable to BPA.
"Plastic bottles and plates that are boiled or put in the microwave or dishwasher are especially problematic because heating them repeatedly causes high amounts of BPA to leach out," says Retha Newbold, a developmental and reproductive biologist at the National Institute of Environmental Health Sciences in Triangle Park, N.C. Once small cracks form in the surface, a product should be discarded. She recommends that parents, to be on the safe side, switch to glass bottles or those with disposable plastic liners that don't contain BPA. And they should use microwave-safe paper plates or glass dishes covered with a paper towel rather than plastic wrap. Some manufacturers, like BornFree, have begun to offer plastic bottles and training cups that are BPA free.