The bottled-water industry is booming, but the stuff you swill could contain more than you bargained for. Some plastics—such as polycarbonate or those with recycling code 7—found in commercial containers and baby bottles leach toxins after repeated use and exposure to high temperatures (Food Additives and Contaminants, 2003, vol. 20, no. 7). The prime offenders? Phthalates and bisphenol-A, says Rachel L. Gibson, staff attorney for Environment California, a citizen-based environmental advocacy organization.

"Both [additives] are linked to numerous adverse effects, including reproductive defects, obesity, diabetes, behavioral problems, and cancers," says Gibson. To avoid harsh chemicals and cut down on waste, replace your plastic with a refillable, leach-free metal alternative from your natural products store. Choose a stainless-steel Klean Kanteen or Swiss-designed SIGG, whose colorful aluminum bottles range from a toddler-friendly 10.2 ounces to a hefty 1.5 liters.

—Krista Crabtree