A. Likely you’re referring to the potential dangers of polycarbonate plastics—often used in reusable water bottles, clear plastic food-storage containers and some baby bottles. Polycarbonates contain bisphenol-A (BPA), an estrogenlike chemical also used in the linings of some food and drink cans. Studies link BPA to the development of precancerous lesions and abnormal development of reproductive systems in animals. While BPA can leach into food and drinks, whether it actually affects human health currently is not known.
What is known is that we’re all exposed to plenty of the chemical. In a 2005 study conducted by the Centers for Disease Control, 95 percent of people screened tested positive for BPA.
A study published in early 2008 in Toxicology Letters suggested that hot liquids and foods exacerbate leaching in BPA-containing plastics. When researchers poured boiling water into polycarbonate drinking bottles, it caused up to 55 times more BPA to seep out than room-temperature water had.
Consumer concern peaked in April after the National Toxicology Program (part of the National Institutes of Health) issued a draft report noting that, given the current science, the possibility couldn’t be ruled out. In September 2008, the U.S. Food and Drug Administration said that BPA is safe for adults and children at current exposure levels.
Whether washing containers in hot water causes them to break down and release BPA the next time they’re used isn’t clear: only a handful of studies have been conducted, and results are conflicting. While heating these plastics in the microwave hasn’t been studied, it’s not recommended. “We assume there is increased leaching with any kind of heating,” says Anila Jacob, M.D., a senior scientist with the Environmental Working Group.
Bottom line: Manufacturers currently aren’t required to label BPA so there’s no way of knowing if it’s present in the plastics or cans you use. For now, the best way to reduce your exposure is to use stainless steel, glass or plastics labeled “BPA-free.” If you’re not sure about a product, recommends Jacob, call the manufacturer.