Studies finding health effects from BPA keep appearing. BPA (bisphenol-A) is a chemical used in many everyday products (e.g. the lining of soda and food cans, store receipts) and so almost all humans are exposed to it daily. Researchers are getting increasingly worried about BPA and related chemicals (including substitutes for BPA such as BPS) because they are endocrine (hormone) disruptors with health effects in humans and animals. This chemical is so widely used that more than 7 billion metric tons of it are produced annually throughout the world.
Unfortunately the US government keeps agreeing with the chemical industry that the chemical is "safe", and disregarding the results of studies finding health effects (reproductive effects, obesity, etc). Of course the chemical industry is fighting tooth and nail to discredit studies done by independent researchers - a lot of money is at stake.
The following are excerpts from an article describing the latest study finding health effects from low dose exposure from BPA - it altered the amount of insulin released by the person (and so perhaps influencing the development of type 2 diabetes). What was worrisome is that the dose is considered "safe" by the US government - and in the study people were exposed to it once, while in real life humans are exposed to such doses multiple times daily.
The good news is that BPA is excreted within a day, but the bad news is that we the keep being exposed to it. By the way, substitutes for BPA (such as BPS) are just as bad, and are also endocrine disruptors - after all, they're all related chemically. So buying BPA-free canned food or plastic won't help a person avoid endocrine disruptors - these also leach into food. From an article written by Lynn Peeples at Environmental Health News:
In a scientific first, researchers gave people BPA — and saw a link to precursor of type 2 diabetes. The controversial study suggests that BPA exposure deemed safe by the feds could alter the amount of insulin released and elevate people's type 2 diabetes risk.
A first-of-its-kind study of a small group of people exposed to a very small amount of bisphenol-A (BPA) is raising questions about the federal government's stance that low doses of the common chemical are safe — as well as the ethics of conducting such an experiment on humans.
The authors say their findings, which they emphasize need to be repeated, build on growing evidence that continued exposures over time to BPA — widely used in plastics, canned food linings and receipt paper — might increase a person's risk of developing insulin resistance and type 2 diabetes.
More than 9 percent of the U.S. population has diabetes — predominantly type 2 diabetes, which means the body struggles to make or use insulin. Multiple factors can raise a person's risk of developing type 2 diabetes including poor diet and lack of exercise.
To this point BPA research has been confined to animal testing and epidemiological studies that compared the health of different populations of people — without purposefully exposing any of them to the chemical. This is the first time researchers have tested BPA on humans, who are exposed daily to the chemicals when they eat, drink and shop.
In the two-part experiment, the researchers tested production of insulin — the hormone that keeps blood sugar levels from getting too high or too low — in response to glucose hitting the bloodstream. Blood samples were taken from each of the 16 participants both after they drank a cocktail containing BPA and at a separate visit, after they drank an identical cocktail that did not contain BPA. In both cases, the cocktail followed administration of glucose — via a drink for the eight participants in part one of the experiment and via an IV for the eight participants in part two.
The amount of insulin released, on average, differed significantly between the visits — higher with BPA exposure in the first experiment, which focused on the early release of the hormone, and lower with the exposure in the second, which focused on the later phase of insulin response. And participants who already had relatively poor blood sugar control seemed more sensitive to BPA's effects.
"We found an effect with a dose of BPA that shouldn't produce an effect," said Angel Nadal, a professor of physiology at the Miguel Hernandez University of Leche in Spain, and study co-author. The dose his team used — 0.05 milligrams of BPA per kilogram of body weight — is presumed safe by the U.S. Food and Drug Administration and the U.S. Environmental Protection Agency. The fact that they found any physiological response in people at that dose, the authors concluded, "would indicate that key assumptions in the regulatory process are incorrect."
BPA is among chemicals capable of mimicking or blocking the natural messages of insulin, estrogen and other hormones in the body. In late pregnancy, hormonal changes are believed to push a woman into a temporary state of insulin resistance in order to ensure enough sugar gets across the placenta to her rapidly growing fetus. The authors posed the possibility that BPA, if mistaken for a steroid by the body, could trigger similar effects.
The chemical has been linked to a variety of health problems including reproductive disorders, behavioral problems, heart disease and obesity.
An association between exposure to BPA and diabetes had been previously found in animal studies and epidemiological studies. However, the FDA and EPA "would not pay attention" to those studies, said Frederick vom Saal, a professor of biology at the University of Missouri-Columbia, and another co-author of the new study. "So we figured we had to look in people."