Bisphenol A, commonly abbreviated as BPA, is an organic compound with two phenol functional groups. It is a difunctional building block of several  important polymers and polymer additives. With an annual production of 2–3 million tonnes, it is an important monomer in the production of  polycarbonate. Suspected of being hazardous to humans since the 1930s, concerns about the use of bisphenol A in consumer products grabbed headlines in 2008 when several governments issued reports questioning its safety, and some retailers pulled products made from it off their shelves.

Bisphenol A has low acute toxicity, with an oral LD50 of 3250 mg/kg in rats, but it is an endocrine disruptor. Low doses of bisphenol A can mimic the body's own hormones, possibly causing negative health effects. There is thus concern that long term low dose exposure to bisphenol A may induce chronic toxicity in humans.

Bisphenol A has been known to leach from the plastic lining of canned foods and, to a lesser degree, polycarbonate plastics that are cleaned with harsh detergents or used to contain acidic or high-temperature liquids. While most exposure is through diet, exposure can also occur through air and through skin absorption. Studies by the CDC found bisphenol A in the urine of 95% of adults sampled in 1988–1994 and in 93% of children and adults tested in 2003–04. Infants fed with liquid formula are among the most exposed, and those fed formula from polycarbonate bottles can consume up to 13 micrograms of bisphenol A per kg of body weight per day (μg/kg/day; see table below). The most sensitive animal studies show effects at much lower doses, while the EPA considers exposures up to 50 µg/kg/day to be safe.

Consumer groups recommend that people wishing to lower their exposure to bisphenol A avoid canned food and polycarbonate plastic containers (which shares resin identification code 7 with many other plastics) unless the packaging indicates the plastic is bisphenol A-free. The National Toxicology Panel recommends avoiding microwaving food in plastic containers, putting plastics in the dishwasher, or using harsh detergents, to avoid leaching.

The federal government (Canadian) has formally declared bisphenol A a hazardous substance as of October 2008 and is now placed on its list of toxic substances. Health officials wrote in Canada Gazette that "It is concluded that bisphenol A be considered as a substance that may be entering the environment in a quantity or concentration or under conditions that constitute or may constitute a danger in Canada to human life or health." The federal ministries of health and the environment announced they would seek to restrict imports, sales and advertising of polycarbonate baby bottles containing BPA.

Excerpt taken from Wikipedia:   http://en.wikipedia.org/wiki/Bisphenol_A