BPA is an acronym for bisphenol - A, a man-made chemical used to make polycarbonate plastics. It is an undisputed fact that, because of the unstable bond between BPA and the plastic, BPA leeches into materials with which it comes into contact, such as baby's milk. A U.S. Centers for Disease Control study has detected bisphenol-A in 93 percent of all Americans. 
Also not up for debate is that BPA is harmful to humans. The only real debate centers around at what concentrations BPA does become harmful.
BPA is commonly found in hard plastics...think Nalgene water bottles (which are now made without BPA), but there are many other products in which BPA can be found, such as the linings of tin cans. Yikes!
The approximate production of this stuff reaches 3,000,000 tons per year. 
As mentioned above, dosage is at the heart of the debate. The chemical industry claims we are not ingesting nearly enough BPA to be harmful. Many government and independent academic scientists disagree saying even low level doses of BPA are linked to "breast and prostate damage, early puberty, behavioral problems, and other effects at levels up to 25 times lower than EPA's 'safe' dose." 
Perhaps even more alarming, and of particular concern to The Glass Baby Bottle, is that the timing of exposure to BPA and other chemicals (like phthalates) can be much more relevant than the dose. Not surprisingly, the most vulnerable times are periods of rapid growth. 
Bioaccumulation is the persistent buildup of some chemicals in our bodies resulting in what is termed a "body burden." A given chemical in our body may actually be safe in isolation, but when combined with a body burden of 700 or so different synthetic chemicals the effects are likely completely unknown. 
Few, if any, studies take bioaccumulation into account. As you might imagine it is a vastly complex issue and virtually impossible to control for in a laboratory setting.
So should you be concerned about BPA? Given its ubiquity in modern life, demonstrably negative effects on humans, especially children -- perhaps at even very low doses -- plus the reality of bioaccumulation, we don't think anybody can stand up and say, with a straight face, that BPA is undoubtedly safe.
The good news is that by educating yourself you put yourself in a position to reduce the exposure to BPA for you and your children when and where you can.
Originally written September 7, 2008
Sources: Environmental Working Group. Chemical Imbalance