BOSTON – Are people exposed to doses of bisphenol A in their canned foods and other consumer products that can harm them? Or are the amounts too low to cause any harm?

This is the crux of a vehement debate that is being waged as federal officials are trying to decide whether the chemical, known as BPA, should be regulated.

A group of toxicologists, including some who work for federal agencies, is questioning the likelihood that BPA is harming human health. But biologists studying the chemical’s health effects disagree, saying that what’s been detected in people is comparable to amounts that have harmed lab animals.

BPA is arguably the most controversial chemical in consumer products. It is used to make polycarbonate plastic as well as food and beverage can liners and some paper receipts and dental sealants

What is widely agreed upon is that exposure is ubiquitous. More than 90 percent of Americans tested have traces of BPA in their bodies.

BPA acts like an estrogen, disrupting hormones In laboratory animals. it alters how their reproductive systems and brains develop, and sets the stage for breast and prostate cancer. People with higher levels of exposure have an increased risk of cardiovascular disease, obesity and diabetes, according to some studies.

Nevertheless, the potential for human effects has been highly controversial among scientists who are debating whether the amounts in people’s bodies are in fact too low to be capable of inflicting harm.

On Friday, some of the toxicologists presented their arguments at the American Association for Advancement of Science annual meeting in Boston.

Do the math. Is it harmful?

On one side of this debate are toxicologists who specialize in analyzing data with mathematical models, producing information often used to set regulatory limits on chemical exposures. Their work focuses not on physical effects observed in animals or cells but on developing models that use numbers to make predictions, in this case to describe the amount of a chemical in the human body and how it may behave.

What is widely agreed upon is that exposure to BPA is nearly ubiquitous. It has been found in more than 90 percent of the Americans tested.On the other side are scientists who study BPA’s health effects in animals and people. They include specialists in genetics, endocrinology, physiology and epidemiology from various academic institutions whose work is supported by the National Institute of Environmental Health Sciences. They have reported health effects in lab animals at very low levels of BPA exposure that they say are comparable to amounts people encounter through consumer products.

This debate, while arcane, is important because the scientific information is being used by the U.S. Environmental Protection Agency and Food and Drug Administration in deciding whether to regulate BPA in consumer products, such as canned foods. Reacting to consumer concerns, some manufacturers already have stopped using BPA in plastic baby bottles, receipts and other items.

Justin Teeguarden, senior scientist at the Pacific Northwest National Laboratory, and Daniel Doerge, research chemist at the FDA’s National Center for Toxicological Research, have produced modeling studies that cast doubt on whether levels of BPA compounds being found in people are having any effects.

At the science conference on Friday, Teeguarden contended that the levels causing effects in animal studies, particularly those caused by BPA’s interaction with estrogen receptors, are much higher than the levels his models suggest are plausible in people. He said he used several methods to examine exposure data from more than 100 studies.

1 Comments

1. 1. jtdwyer 01:19 PM 2/20/13

   The animal studies were based on “exposure levels much higher than has been measured in most human blood samples and is therefore not sufficient evidence on which to make claims that humans are at risk at current exposure levels.”
   
   The above is a truly naive statement!
   
   Please see
   http://en.wikipedia.org/wiki/Bisphenol_A#Expert_panel_conclusions
   
   "In 2006, the US Government sponsored an assessment of the scientific literature on BPA. 38 opponents of bisphenol A gathered in Chapel Hill, North Carolina to review several hundred studies on BPA, many conducted by members of the group. At the end of the meeting, the group issued the Chapel Hill Consensus Statement, which stated "BPA at concentrations found in the human body is associated with organizational changes in the prostate, breast, testis, mammary glands, body size, brain structure and chemistry, and behavior of laboratory animals."
   
   "The Chapel Hill Consensus Statement claimed that average levels in people are above those that cause harm to many animals in laboratory experiments. They noted that while BPA is not persistent in the environment or in humans, biomonitoring surveys indicate that exposure is continuous, however, which is problematic because acute animal exposure studies are used to estimate daily human exposure to BPA, and no studies that had examined BPA pharmacokinetics in animal models had followed continuous low-level exposures. They added that measurement of BPA levels in serum and other body fluids suggests the possibilities that BPA intake is much higher than accounted for, and/or that BPA can bioaccumulate in some conditions (such as pregnancy). A 2011 study, the first to examine BPA in a continuous low-level exposure throughout the day, did find an increased absorption and accumulation of BPA in the blood of mice."
   
   [references ommited]

   Reply | Report Abuse | Link to this