Vom Saal is a prominent member of a group of researchers who have raised worrisome questions in recent years about the safety of some common types of plastics. We think of plastic as essentially inert; after all, it takes hundreds of years for a plastic bottle to degrade in a landfill. But as plastic ages or is exposed to heat or stress, it can release trace amounts of some of its ingredients. Of particular concern these days are bisphenol-a (BPA), used to strengthen some plastics, and phthalates, used to soften others. Each ingredient is a part of hundreds of household items; BPA is in everything from baby bottles to can linings (to protect against E. coli and botulism), while phthalates are found in childrens toys as well as vinyl shower curtains. And those chemicals can get inside us through the food, water and bits of dust we consume or even by being absorbed through our skin. Indeed, the Centers for Disease Control and Prevention reported that 92% of Americans age 6 or older test positive for BPA--a sign of just how common the chemical is in our plastic universe。
Scientists like vom Saal argue that BPA and phthalates are different from other environmental toxins like lead and mercury in that these plastic ingredients are endocrine disrupters, which mimic hormones. Estrogen and other hormones in relatively tiny amounts can cause vast changes, so some researchers worry that BPA and phthalates could do the same, especially in young children. Animal studies on BPA found that low-dose exposure, particularly during pregnancy, may be associated with a variety of ills, including cancer and reproductive problems. Some human studies on phthalates linked exposure to declining sperm quality in adult males, while other work has found that early puberty in girls may be associated with the chemicals。
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