A recent article published by Rodale News uncovers the fact that BPS is often used in “BPA Free” plastic. According to the article, BPS is just as toxic as BPA, read more here: http://www.rodalenews.com/bpa-free-safe
For me, I’ve decided to keep to Stainless steel and I also like Nalgene Bottles as they are BPA, BPS and Phthalate free.