MONDAY Sep. 8, 2008 (foodconsumer.org) -- A study published in the April 2008 issue of International Journal of Andrology suggests that exposure to bisphenol A (BPA), a toxic chemical commonly present in the polycarbonated plastic and epoxy resins used for food and beverage containers, may increase risk of type 2 diabetes, a condition that affects nearly 24 million Americans suffer diabetes.

The study conducted by Ropero AB and colleagues from Universidad Miguel Hernández de Elche in Alicante, Spain demonstrated a link between bisphenol A, an endocrine disruptor and altered blood glucose metabolism in mice.

The researchers found BPA exerted rapid effects on insulin releasing beta-cells and glucagon releasing alpha-cells within freshly isolated The endocrine cells of the pancreas after a short time of exposure.

Male mice rapidly increased blood insulin and decreased glycaemia when exposed to 10 mcg/kg of BPA. At the dose of 100 mcg/kg/day for 4 days, the environmental estrogen resulted in an increase in beta-cell insulin along with postprandial hyperinsulinaemia and insulin resistance.

The U.S. Environmental Protection Agency sets the reference dosage of bisphenol A, which is believed to be safe, at 50 mcg/kg/day. The results of the current study suggests that BPA at a level lower than the EPA standard may potentially boost the risk of developing type 2 diabetes in humans.

Another study conducted by Alonso-Magdalena P and colleagues also from Universidad Miguel Hernández de Elche, Alicante, Spain and published in the Jan 2006 issue of Environmental Health Perspectives showed the toxic effect of BPA starts at the level of 10 mcg/kg.

The researchers found that 2 days after treated with 10 mcg of BPA/kg of body weight/day, mice experienced an increase in pancreatic beta-cell insulin content. After 4 days of the treatment, "the mice developed chronic hyperinsulinemia, and their glucose and insulin tolerance tests were altered," the authors wrote.

A most recent study published online in Environmental Health Perspectives on August 14, which was reported by foodconsumer.org on Sep 1, 2008, found bisphenol A at the level found commonly found in humans' blood can suppress a hormone that protects people from heart attacks and type 2 diabetes.

The study led by Nira Ben-Jonathan, an endocrinologist at the University of Cincinnati in Ohio showed the level of adiponectin, a protective hormone released by human breast fat cells decreased after exposure to bisphenol A. The effective levels of the chemical were commonly found in human blood.

In the study, the researchers exposed some human cells to estradiol, a natural human estrogen and some to bisphenol A.    Both groups of cells released reduced amounts of the protective hormone adiponectin, which protects against heart attacks and type 2 diabetes.

"These findings provide the molecular basis for bisphenol A being implicated in both obesity and potentially the associated disease that is now being detected in children and adolescents -- type 2 diabetes," Frederick vom Saal, a specialist in endocrine disruptors from the University of Missouri in Columbia was quoted as commenting.

The National Toxicology Program Sept 3 released a final report on bisphenol A saying that the current human exposure to this chemical is of "some concern for its effect on development of the prostate gland and brain and fetuses, infants and children. But the government agency does not recognize the potential impact of BPA on diabetes risk.