Wednesday Sep 17, 2008 (foodconsumer.org) – Early studies suggest that bisphenol A or BPA may damage the brain, reproductive system and immune system.   A new observation study now suggests that the chemical may raise risk of heart disease, diabetes and liver malfunctions, two major diseases that plague developed countries.

BPA, widely used in everyday plastics including baby bottles, food containers and epoxy resins used in canned food was present at much higher levels in people with heart diseases, diabetes and liver abnormalities, the study found.

For the study, published Tuesday in the Journal of the American Medical Association, researchers from the UK and the University of Iowa went through the data on the BPA level in the urine samples from 1,455 men and women and found the disturbing associations.

The researchers found those in the quartile with the highest levels of BPA were three times as likely to have cardiovascular disease and 2.4 times as likely to have diabetes as those in the quartile with the lowest level. Those with highest levels were also found at higher risk of abnormal levels of three liver enzymes.

The study was not a trial and did not reveal a causal relationship between high levels of BPA and high risk of heart disease and diabetes, meaning that BPA does not necessarily cause the diseases. The industry has long maintained that there is no significant concern about the safety of bisphenol A.

Regardless, a health observer who does not want to be named said the study still points to the possibility that BPA may have something to do with the increased risk of heart disease and diabetes.   Some early studies have already indicated that such a possibility is more likely than not.

BPA is known as an endocrine disruptor.  An early study has found that BPA exerted rapid effects on insulin releasing beta-cells and glucagon releasing alpha-cells within freshly isolated endocrine cells of the pancreas after a short time of exposure.

The study showed 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 study was conducted by Ropero AB and colleagues from Universidad Miguel Hernández de Elche in Alicante, Spain and published in the April 2008 issue of International Journal of Andrology.

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 this study suggest 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 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.

Early on Sep 3, the National Toxicology Program 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 the heart disease and diabetes risk.

The Food and Drug Administration said early and said again at the time of releasing the new study that bisphenol A poses no risk at the current level of exposure, but only acknowledged that further studies are needed.

Sen. Charles Grassley, R-Iowa and some of his Democratic colleagues are reportedly looking into whether the FDA opinion has been unduly influenced by the chemical industry, news media reports.