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Bisphenol A is an chemical compound that is prepared by reaction of two equivalents of phenol with one equivalent of acetone. Its chemical structure is shown at right. Bisphenol A belongs to the phenols class of aromatic organic compounds, having two phenol functional groups in its molecule.
Bisphenol A was invented in the 1930's during the search for synthetic estrogens. At that time, another synthesized compound, diethylstilbestrol, turned out to be more powerful as an estrogen, so bisphenol A was shelved until polymer chemists discovered that it could be polymerized to form polycarbonate plastic. Its current main use is in the manufacture of polycarbonate polymers and epoxy glues.
Polycarbonates are widely used in all sorts of consumer products, from sunglasses and CDs to water and food containers and shatter-resistant baby bottles. Some polymers used in dental fillings also contain bisphenol A, while epoxy resins containing bisphenol A are popular coatings for the inside of cans used for canning food.
The first evidence of bisphenol A's estrogenicity came from experiments in the 1930's feeding BPA to ovariectomised rats (Dodds and Lawson 1936, 1938). Some hormone disrupting effects in studies on animals and human cancer cells have been shown to occur at levels as low as 2-5 ppb (parts per billion).
The plastics industry has long claimed that bisphenol A is safe at typical levels of human exposure, minimizing or discounting all tests to the contrary. Eleven industry-funded studies found no risk from bisphenol A, while 90% of 104 independent studies showed possible risks, says a December 2004 report from scientists Frederick vom Saal and Claude Hughes
A previous report, released by the Harvard Center for Risk Analysis and funded by the American Plastics Council, called the evidence for risks "weak" and "inconsistent".
==External Sources:== "Study Cites Risk of Compound in Plastic Bottles" - LA Times
Plastics Industry Bisphenol A information site
Bisphenol Info page of a site about dangers of endocrine disruptors