Exposure to Safe Levels of BPA May Still Affect Insulin Response in Humans

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By : Suvarna Sheth

In a first of its kind study, researchers have found that exposure to levels of bisphenol A (BPA) deemed to be “safe” by the U.S. Food and Drug Administration (FDA) may actually be enough to have implications for the development of Type 2 diabetes.

BPA has been known to be an endocrine-disrupting chemical that is used in a wide array of consumer goods including plastics, the lining of canned foods and even cash-register receipts, to name just a few.

Professor Frederick Vom Saal, an endocrinologist in the division of biological sciences in the MU College of Arts and Science, and a co-author of the study wanted to test whether the FDA allowed daily exposure amount of BPA is actually safe.

Professor Fred Vom Saal. Credit: MU News Bureau

“Experiments with human and mouse pancreatic cells have revealed that low-dose exposure to BPA, in the presence of glucose, triggers an insulin response,” Vom Saal said in a press release. “We wanted to test the potential effects of BPA in humans to see whether it held true.”

How Was the Study Conducted?

The study was carried out on humans without diabetes.

In the first group, 16 volunteers were orally given a safe dose of BPA. The amount was equivalent to the amount of BPA that customers might encounter by handling a cash register receipt. At a separate visit, the group received a placebo exposure for comparison.

In both instances, the subjects were administered glucose after, one half via a drink, the other half through an IV. The subjects were then tested for their insulin production in response to glucose, commonly called blood sugar.

When insulin and blood glucose levels were compared to the same measurements taken without exposure to BPA, researchers found that BPA significantly changed how glucose affected insulin levels.

In animal studies, repeated BPA exposure resulted in insulin resistance.

Some Find Study Controversial

This is the first time researchers have tested BPA in humans.

According to an article in Environmental Health News, The American Chemistry Council, which represents chemical manufacturers, called the new human exposure study “speculative” and stated the results do not demonstrate that the effects of BPA are related to diabetes.

The American Chemistry Council also questioned the ethics of using human volunteers.

“It’s a little ironic that they are trying to show very low levels of BPA might be dangerous but using the criteria of agencies that say it’s not dangerous,” Sheldon Krimsky, a professor at Tufts University told Environmental Health News.

However, Krimsky points out “One of the justifications for doing the test is that the levels they administered were within the federal guidelines.”

Vom Saal said they took the ethical considerations very seriously — working for more than two years with the Institutional Review Board at the University of Missouri to address concerns with the study design. The board ultimately approved the experiment.

The study, “Experimental BPA Exposure and Glucose-Stimulated Insulin Response in Adult Men and Women,” was published in the Journal of the Endocrine Society.