New scientific studies link bisphenol-a (BPA), a chemical used in the manufacture of durable plastic bottles, food-can linings and dental fillings, to a host of serious maladies. BPA is one of many man-made chemicals classified as endocrine disruptors, which alter the function of the endocrine system by mimicking the role of the body's natural hormones. Hormones are secreted through endocrine glands and serve different functions throughout the body. Polycarbonate, based on BPA, has therefore come under cloud. While a growing number of scientists say animal and cell-culture studies link low-dose BPA exposure to everything from altered neural development to reproductive system deformities to cancer, other researchers say the findings are inconclusive at best, irrelevant and fear-mongering at worst. While Canada reportedly is close to declaring BPA to be a toxic chemical (being the first country to do so), the U.S. Food and Drug Administration (FDA) says there is no compelling proof that BPA harms people. While the chemical industry adamantly, even aggressively, insists BPA presents no measurable health risk to humans and cites 50 years of safe use, the marketplace appears to be abandoning the chemical. Nalgene, the maker of hugely popular polycarbonate water bottles; Playtex, which makes baby products containing BPA, retailers including Wal-Mart and Toys �R� Us have announced plans to switch to selling only BPA-free baby bottles, teething rings and other products because of consumer concerns. For the consumer, these contradictory actions are encouraging as well as alarming. Many experts say it is prudent to reduce, if not avoid, at least some kinds of plastics in certain situations.
Recently the National Toxicology Program, part of the federal National Institute of Environmental Health Sciences in USA issued a draft report highlighting research that showed some lab rats fed or injected with low doses of BPA reached puberty early, had urinary tract problems or developed precancerous tumors. The agency described the evidence as limited but said the possibility that bisphenol-a may alter human development cannot be dismissed. The draft report marked the first time that a U.S. government agency had expressed public concern about possible health risks posed by BPA. A call for further research is expected.
Lack of research is at the heart of the conflict and confusion over BPA. The studies suggesting low-dose BPA exposure provokes adverse responses in cells and in test animals. The problem is that no one can say with certainty that these findings translate to humans. BPA can undoubtedly behave as estrogen mimics. The issue is the level of exposure, in particular what people actually experience. Many studies suggest it is significant. With improved tools and techniques, researchers are reporting measurable effects from BPA at levels well below those declared safe by government regulators and industry scientists. Some research indicates humans may be exposed to more BPA than previously thought � that under certain conditions, these chemicals leach out of plastic in higher-than-expected amounts.
A much-reported study this year at the University of Cincinnati found that polycarbonate baby bottles exposed to boiling water, meant to simulate prolonged use and multiple washings, released 55 times more BPA than bottles exposed only to hot water. Other research has shown that old, scratched polycarbonate plastic leaches chemicals more readily than newer material. As per this research, bottles used for up to nine years released the same amount of BPA as new bottles. Additionally, the amount of BPA released from new and used polycarbonate drinking bottles was the same -- both in quantity and speed of release -- into cool or temperate water. However, drastically higher levels of BPA were released once the bottles were briefly exposed to boiling water. Prior to boiling water exposure, the rate of release from individual bottles ranged from 0.2-0.8 nanograms/hr. After exposure, rates increased to 8-32 nanograms/hr.
It is still unclear what level of BPA is harmful to humans. The chemical industry counters these reports with other studies citing no significant adverse effect from BPA. Industry spokesmen say the government backs up their position, noting the FDA's announcement last year that it knew of no research compelling enough to merit restricting or banning BPA. Last month, FDA officials conceded the conclusion was based on just two industry-funded studies. Meanwhile,
Department of Health and Human Services in USA has compiled these tips for reducing exposure to BPA: :

•	Don't microwave polycarbonate plastic food containers. Polycarbonate may break down from overuse at high temperatures and release BPA. (Manufacturers are not required to disclose whether an item contains BPA, but polycarbonate containers that do usually have a No. 7 on the bottom.).
•	Reduce use of canned foods, especially acidic foods such as tomatoes that can accelerate leaching of BPA from the plastic can linings. Opt for soups, vegetables and other items packaged in cardboard "brick" cartons, made of safer layers of aluminum and polyethylene plastic (labeled No. 2)
•	Switch to glass, porcelain or stainless steel containers, particularly for hot food or liquids.
•	Use baby bottles that are BPA-free; in the last year, most major manufacturers have developed plastic baby bottles made without BPA.

Foetuses, infants and children around puberty are at maximum risk. Foetuses are especially sensitive groups as their immature detoxification systems make them more vulnerable and they are at a delicate stage of development. While there has been credible evidence on low-dose impacts of BPA, many countries are hesitant to adopt more stringent regulations until new studies are conducted that reproduce the data previously found.