This month's Backcountry.com newsletter features an article on plastic water bottle concerns and alternatives. Some of you may be aware that Canada's largest outdoor retailer recently pulled polycarbonate (Lexan) water bottles from its shelves, citing safety concerns about the ingredient BPA, which leeches from polycarbonate plastics, and which acts like a hormone when ingested by lab animals.
The plastic industry (and of course Nalgene) insist that BPA-leeching is not a health concern, and they've got some substantial evidence to support their case, including current statements by a variety of health organizations.
Coincidentally, I've been putting together a section on hydration product reviews for SierraDescents, including my take on the subject of toxic exposure. That should be coming within a week or so. For now, check out the Backcountry article. Unfortunately, I think the waters are going to remain muddy on this subject for a while.