A close look at the plastics industry’s spin on BPA

One thing I’m very concerned about these days is bisphenol A, or BPA, the chemical that has become famous for turning up uninvited in plastics, tinned food cans, shopping receipts, and—surprise!—us. A whopping 95 percent of Americans have traces of this plastic building block in their bodies, according to the CDC in Atlanta.

BPA mimics the hormone estrogen, binding to its receptors and activating biochemical cascades that impact the brain, bone, liver, and heart as well as cancer risk, fertility, and obesity. Hormones like estrogen aren’t just responsible for reproduction; they are the messengers the body uses to communicate about pretty much everything.  And they are incredibly potent, having “evolved to act as powerful amplifiers,” according to a 2005 commentary published in Environmental Health Perspectives.

Low levels of BPA have been shown to increase the risk for infertility, organ and nervous system problems, cancer, and obesity in animals, and a 2008 study published in the Journal of the American Medical Association found that people who have high levels of BPA in their urine are more likely than others to suffer from heart disease and diabetes. (A 2010 study in PLoS One has confirmed the heart disease findings.)

Still, an informational website maintained by the American Chemistry Council, the trade group that represents the plastics industry, maintains that “there is no basis for human health concerns from exposure to BPA.” Dig a little deeper, and I find that most of the industry’s claims about BPA’s safety are spurious. Here are five industry arguments that just don’t stand up to scrutiny—for reasons, I’m sure, they would prefer you didn’t know.

WHAT THEY SAY: “BPA is one of the most extensively tested materials in use today… The weight of scientific evidence clearly supports the safety of BPA and provides strong reassurance that there is no basis for human health concerns from exposure.”

THE TRUTH: It’s true that BPA has been studied quite extensively, although more research is desperately needed. But does the weight of the evidence support the safety of BPA? No way. According to TEDX, the Endocrine Disruption Exchange, a non-profit organization founded by University of Florida Gainesville biologist Theo Colborn, which compiles information about endocrine disruptors like BPA, as of June 2009, 391 studies have assessed the effects of 1 part per million exposures to BPA—a level 50 times lower than the EPA’s recommended safe dose. 82 percent of the studies reported that BPA caused significant biological effects at these tiny doses; only 18 percent found no effect.

WHAT THEY SAY: “The most definitive tests of BPA’s safety at low doses are two large-scale reproductive and developmental toxicity studies using accepted protocols. Both of these studies clearly demonstrated the absence of a low-dose effect of BPA.

THE TRUTH: Oh yes, those two studies. The same ones that the FDA relied for in its 2008 safety assessment of BPA, in which the agency deemed the chemical safe. Upon being questioned by Congress later that year, the FDA admitted that the two studies were funded by the American Plastics Council, an obvious conflict of interest. (Among other things, one of the studies used a strain of rat that is not sensitive to estrogen disruption.) In addition, the Milwaukee Journal Sentinel uncovered that a medical device manufacturer that considers BPA fears to be exaggerated gave $5 million to Martin Philbert, the chairman of the agency’s BPA safety panel. In 2009, Congress concluded that these findings “raised serious questions about the extent to which FDA relied on the industry for independent scientific advice,” and sent the agency back to the drawing board. Finally, in January of this year, the agency admitted, along with the National Toxicology Program, that it had some concern about the safety of the chemical and its effects on the brain, behavior, and prostate gland of fetuses, infants and children.

WHAT THEY SAY: Findings from human studies “cannot support a conclusion that bisphenol A causes any disease.”

THE TRUTH: This is true, but what’s important to understand is why it is true, and why there aren’t more data. Certainly, if a study finds that people who have more BPA in their bodies are more likely to have heart disease and diabetes, that doesn’t mean that BPA necessarily causes heart disease and diabetes. But when it comes to BPA, it’s practically impossible for scientists to prove causality. Researchers can’t compare the health of people who are exposed to BPA to the health of people who are not, because we’re all exposed. There is no control group, and without a control group, scientists have no means for comparison.  (My husband made this point on the radio last week, should you be interested in hearing it.) So yes, the results from human studies aren’t definitive, but that is not evidence that BPA is safe. It’s evidence that the situation has become so dire, we can no longer ascertain what the chemical does to us.

WHAT THEY SAY: “You’d have to ingest more than 500 pounds of canned food and beverages every day for an entire lifetime to exceed the safe level of BPA set by the EPA.

THE TRUTH: First, this ignores the fact that we are exposed to BPA from a range of sources. Water bottles, food storage containers, shopping receipts (which the Environmental Working Group recently showed contain up to 1000 times more BPA than tin cans do)—the list goes on and on. Second, the EPA’s safety assessment was only designed to look at gross changes in development, mortality, body weight, and tumor incidence and were “not designed to detect more subtle developmental effects that impact the health of the individual,” according to a 2009 study published by Tufts University researchers in Endocrine Reviews. In addition, the EPA assessment involved testing only adult animals, so it says nothing about how BPA might affect the offspring of animals treated during pregnancy, an important window of vulnerability. Finally, as explained earlier, hundreds of studies have found evidence that BPA causes problems at doses lower than the EPA’s safe level. And at least 11 studies have even found BPA to cause problems at low doses but not at higher doses, for as yet unknown reasons.

WHAT THEY SAY: BPA is integral to the production of plastic and epoxy resins.

THE TRUTH: If that were true, then Gerber, Nalgene, Eden Organic, and a number of other companies that have voluntarily phased out BPA must have had some serious tricks up their sleeve. This is my biggest problem with the plastics industry: no, we don’t know enough about it to definitively conclude what it does. We can’t prove that it causes this disease or that disease. But does that really matter? The hundreds of studies we do have are highly concerning, and since companies don’t have to use BPA to make their resins and plastics, why don’t we just play it safe and get rid of it for good?

To me, that seems like a no brainer.

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9 Responses to A close look at the plastics industry’s spin on BPA

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  2. Khalil A. says:

    My dad is becoming increasingly paranoid about using plastic bottles and, well, I daresay this reassures me that his paranoia doesn’t look like another grumpy old man’s word!

    And it’s as though, the plastic industry has been busted by Melinda :P Nice post, nice blog, looking forward to reading more.

  3. Thalia says:

    Normal toxicology states that “the dose makes the poison.” The response curve for most toxic elements starts low, with a low dose. The response increases with the dose, in a straight line rising from right to left.

    Endocrine hormones have a U shaped response curve. The level of hormone naturally released in the body is miniscule; the receptors are designed to bond and respond to these natural levels. That is why the left hand curve of the U-shaped response curve is high. There is a high response to low dose. The center of the U-shaped curve is low. At the medium levels, what a toxicologist would consider significant for other elements, the receptors shut down. When the dosage becomes extremely high, it forces the body to respond. That is the right hand upslope of the U shaped curve.
    The plastic industry disengenuosly utilizes the language of standard toxicology, which begs the point. Endocrine hormones are MOST effective at the smallest exposure, because that most closely mimics the natural hormones in the body.

  4. Thalia says:

    The response increases with the dose, in a straight line rising from LEFT to RIGHT.

  5. M. Muno says:

    Is there a good reference for the “U-shaped response curve”, that causes a chemical to have small (or no) effect at low and high doses, but a noticeable one at intermediate doses?

    I did a little reading on this, and the main reference seems to be this Environmental Health Perspectives review. However, I found that the examples cited in the paper did not support the “U-shaped curve”, nor the more general suggestion (made, for instance in another review) that a chemical can be harmful at low doses, but have no noticeable effect at high doses.

    The only similar case seems to be Tamoxifen in which low doses have negative effects treating cancer, until the concentration becomes high enough that it positive effects dominate. That, however, could be modeled with two response curves, a negative effect that plateaus at low doses, and a positive effect that dominates at higher ones.

    I do not have a strong background in biology, but as a physicist, I find it hard to make sense of how a U-shaped curve can occur. I’ve asked around a bit, but have not found a good explanation.

  6. Gingerbaker says:

    Years ago, I did studies on the effects of Tamoxifen on steroid metabolism. I found that Tamoxifen sticks to glass test tubes very readily, and also to many types of plastic labware and plastic test tubes.

    I have doubts if most labs realize this, which might explain the results you describe.

  7. Thanks, all, for your comments. I find the research on U-shaped and inverted U-shaped dose-response curves to be incredibly fascinating. M. Muno, if you’d like to read more about it, I’d suggest you look at the research of Edward Calabrese, a toxicologist at the U Mass-Amherst. He refers to this kind of dose-response as hormesis, and he thinks it’s the norm, not the exception. There’s also a journal, Dose Response, pretty much dedicated to the study of hormesis, which you might want to check out. If it’s true that these endocrine disruptors follow a U-shaped curve, as Thalia suggests, then we really do need to be worried about low dose exposures.

  8. Great post. It was just a few weeks ago that I had a Tupperware rep tell me that the BPA thing was all just a media hype. I tried to politely explain that it really wasn’t. Your post did it in a clear and well doucmented way. Thanks.

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