Bottles made of polycarbonate (#7 on the bottom) are those most strongly implicated in such studies. So if you are worried about this issue check your Nalgene bottles for the #7. According to Chemistry World, The FDA maintains that there is no reason to ban or restrict the use of BPA in food or drink containers because human exposure levels to the chemical from these sources is too low to have any adverse effects. At present the evidence for adverse health effects from BPA from food and drink containers is controversial. However if you want to completely eliminate any possibility that it could be dangerous to your health here are 7 ways to beat BPA, in order of Importance: 1. Ditch the clear plastic baby bottles, right now. All the research that says there are problems point at the effect of the estrogen-like BPA on children as being the most significant. 2. Tin cans are often lined in plastic BPA and sit around a long time; get rid of older tin cans, particularly if they contain tomatoes and other acidic fruits. These cases may pose an even bigger risk than the plastic bottles. 3. Don't use your polycarbonate bottle for hot drinks. 4. Polycarbonate bottles get crazed and cracked as they get older; that increases surface area. Get rid of old ones. 5. Replace your Polycarbonate bottle with a Sigg, Kleen Kanteen, or the new BPA free Camelbak, particularly if pregnant or pre-pubescent. 6. Replace jugs where water sits around a long time, like Brita knockoffs. (Brita says they are BPA free) 7. Stop using jugged water cooler water, get a filter and cooler that uses city water.

more data available at http://www.ewg.org/node/20940