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Bisphenol A is an organic compound composed of two phenol groups that is produced by condensing acetone with carbolic acid. It is also known as 4,4'-dihydroxy-2,2-diphenylpropane, or simply BPA. Bisphenol A is used as a reactive monomer to polymerize proteins, which initiates a chemical process that leads to the formation of polymer chains. As such, Bisphenol A is produced in mass quantities for the primary purpose of manufacturing polycarbonate plastics and epoxy resins.
Polycarbonate plastics are used to make a variety of products, including eyeglass lenses, bullet-proof glass, medical and safety equipment, compact discs and plastic bottles. Epoxy resins are used to line or coat products, such as canned goods, plumbing, plastic tableware, plastic food storage containers, and bottle caps and lids. In the case of plastics, items marked with a 1, 2, 4, 5, or 6 recycling code are unlikely to contain Bisphenol A; those marked 3 or 7 may be made with BPA, although this code does not mean that they definitely are.
While Bisphenol A has been used commercially for more than half a century, it has only become familiar to consumers in recent years. This is due to concerns over the impact of Bisphenol A on the environment and human health. Environmental studies indicate that this organic compound interferes with nitrogen uptake in certain plants, namely legumes such as beans. Several studies have also found levels of Bisphenol A in municipal wastewater. In addition, it has been determined that Bisphenol A is harmful to marine life.
In studies using animal models, low level exposure to Bisphenol A has resulted in several adverse health effects being observed. These effects include changes in breast tissue, the early onset of puberty, a decline of testosterone production, and an increase in prostate weight, among others. However, these studies involved the injection of high levels of Bisphenol A and may not accurately represent normal exposure.
In terms of the impact of long-term exposure of Bisphenol A on humans, the Centers for Disease Control and Prevention has found that nearly 95 percent of Americans over the age of six have low levels of Bisphenol A that can be detected in their urine. Researchers believe that Bisphenol A may enter the body through regular consumption of foods and drinks packaged in materials that have been treated with the substance. Aside from consuming canned goods and drinking from plastic bottles, exposure may also come from drinking some wines or even having teeth sealed.
Of particular concern is the possibility that Bisphenol A may be leaching from BPA-treated products, including plastic water bottles and infant bottles. However, exposure can also occur from air pollution and absorption through the skin. While more research is needed, preliminary studies on humans suggest that high levels of Bisphenol A in the body are associated with an increased incidence of diabetes and heart disease. In addition, this compound is known to be an endocrine disruptor due to possessing estrogen-like properties.
According to the National Institute of Environmental Health Sciences, consumers may be able to reduce to Bisphenol A exposure by choosing glass containers over plastic. In addition, placing hot liquids into plastic bottles or cleaning them in the dishwasher should be avoided, since temperature seems to affect Bisphenol A release.