Updated 3/2017-- all links (except to my own posts) removed
as many no longer active. and it was easier than checking each one.
I love the convenience of my microwave. It is especially good for reheating leftovers like the chili I made recently. I took the chili to the office in a plastic container for lunch the next day. The question is: are the BPAs in the plastic container a health risk? Should I put my chili in a Pyrex or ceramic bowl before microwaving?
Yesterday afternoon, I participated in Better Health's very first blogger briefing. The subject was Bisphenol-A (BPA) plastic safety. The briefing included an interview with Steve Hentges, PhD., Executive Director of the Polycarbonate/BPA Global Group of the American Chemistry Council (ACC), and was moderated by Dr. Steven Novella, founder of the blog Science-Based Medicine and the new policy non-profit, The Institute For Science In Medicine.
Bisphenol-A (BPA) is a chemical widely used to produce polycarbonate, a hard plastic. More than 2 million metric tons of BPA were produced worldwide in 2003. There is an increase in demand of 6% to 10% annually. BPA can be found in a wide range of products, including baby bottles, plastic utensils, and plastic food containers. It has been the focus of some controversy over its safety, and the resulting debate reveals much about how the current system deals with such issues.
The concern is that BPA can leech from plastic containers into the food or liquid it contains, and when consumed can have negative health effects. The debate is over how to interpret existing evidence about BPA safety, which gives conflicting results. Essentially it is a debate about how to weight different kinds of evidence, and where safety thresholds should be.
The Food and Drug Administration is getting ready to look at this question of BPA safety again. The history of the FDA’s stance is as follows (dated Aug 31, 2009):
In August 2008, FDA released a draft report finding that BPA remains safe in food contact materials. On October 31, 2008, a subcommittee of FDA's science board raised questions about whether FDA's review had adequately considered the most recent scientific information available. Most recently, on June 3, 2009, FDA Commissioner Dr. Margaret A. Hamburg testified before the House Committee on Energy and Commerce's Subcommittee on Health (written testimony is available at http://www.fda.gov/NewsEvents/Testimony/ucm164186.htm).
In response to a question about BPA, Dr. Hamburg emphasized that she takes the questions that have been raised about BPA very seriously, and she stated that the FDA's new Acting Chief Scientist, Dr. Jesse Goodman, is working with FDA scientists to take a fresh look at the science of BPA. FDA intends to explain the results of this review in late summer or early fall.
In August 2009, Massachusetts joined Connecticut in taking a stance on BPA. Connecticut has banned the use of BPA from infant formula and baby food cans and jars, as well as in reusable food and beverage containers sold with the state. Massachusetts has considered the same ban, but for now has only told parents of young children to avoid using baby bottles and other food and beverage containers made with the plastic-hardening chemical bisphenol A (BPA). Massachusetts is waiting the FDA’s decision on BPA.
As of the spring of this year, six major companies have agreed to stop selling hard-plastic baby bottles which contain bisphenol-A in the United States. The companies decision was in response to growing public concern. The companies are Playtex Products Inc., Gerber, Evenflo Co., Avent America Inc., Dr. Brown and Disney First Years.
From the FDA Draft Assessment:
Exposure of adults or infants to residual BPA through uses in food additives is relatively low (i.e., no more than 11 μg/person/day for any segment of the population). Traditionally, FDA’s evaluation of chemical migrants to food from the use of food contact materials at exposures of ≤ 150 μg/person/day focuses primarily on carcinogenicity and on genetic toxicity as an indicator of carcinogenicity1, unless data are available (biological or predictive) that indicate a concern for another endpoint of toxicity at this level.
It is well documented that BPA binds to estrogen receptors (ERα and ERβ), although its affinity is orders of magnitude lower than that of endogenous estrogen2,3. In addition, several in vitro studies have indicated that BPA may also interact with other receptors, including membrane bound ER and estrogen-related receptor γ (ERR γ)4. Since the late 1990s, a large volume of research has been generated suggesting a possible ‘low’ dose effect for weakly estrogenic environmental contaminants, such as BPA. The National Toxicology Program (NTP) defines ‘low’ dose for BPA as ≤ 5 mg/kg bw/day5
While BPA may bind to estrogen receptors, its metabolites don’t. The oral route is most important in this discussion. BPA is rapidly metabolized to the monoglucuronide and cleared from the body via urinary excretion. The metabolite, monoglucuronide, is biologically inactive. BPA does not accumulate in body fat or sex organs of either male or female test animals given either 10 or 100 milligrams per kilogram body weight of bisphenol A administered by oral exposure, or intraperitoneal or subcutaneous injection.
So while scientist will continue to look at BPA and its safety, I will feel safe in using plastic water bottles. I will feel safe in storing my leftovers in plastic containers. I will feel safe in reheating my leftovers in those plastic containers.
Listen to the briefing here at Better Health.
Sources
Bisphenol A in Plastics – Should We Worry? by Steven Novella (September 17, 2008)
Bisphenol A (BPA) -- FDA
FDA DRAFT Assessment of Bisphenol A for Use in Food Contact Applications (2008)
Pharmacokinetic Studies and Bisphenol A Metabolism
