In fact, when I spoke to Dr. Michael Hansen, senior scientist at Consumers Union, the nonprofit publisher of Consumer Reports, he pointed out that this study did find detectable BPA levels in three subjects, but for reasons that are not well explained, they were excluded.
Another mystifying element of this paper involves water–and lots of it. The study participants drank 3.5 liters of water each day of the study. That’s about three and half times the amount most people drink in a day, Hansen explained. And while most BPA research uses methods to account for dilution caused by water, this study did not.
To conduct the research, Teeguarden applied what are called “toxicokinetic” techniques, which involve examining exactly how a chemical breaks down in the bloodstream and precisely what happens as it interacts with the human body. While that sounds like a helpful way to approach BPA, Vandenberg believes that there are significant problems with relying on toxicokinetic techniques to analyze BPA exposure. In fact, she has written extensively about those problems. She concludes, in essence, that both the current toxicokinetic tools as well as the scientific understanding of BPA are limited enough that these techniques alone could lead a researcher down the wrong path.
Another odd feature of this study that caught Vandenberg’s attention was that, for key citations regarding how the body handles BPA and how much BPA people consume, the study relied on industry-funded work that many scientists consider to be flawed. Vandenberg couldn’t come up with a reason why Teeguarden would do this.
For his part, Teeguarden vigorously defended his work to me in an email. As for his use of toxicokinetics, he said:
If it is so problematic, why has it been identified as so important and why are so many people working on it? …The truth is, without the information we obtain from measuring BPA in the blood of animals and humans, we have no basis for assessing hazard in the human population.
This is undoubtedly true. However, scientists who have applied this technique to BPA say that it simply can’t yet do the “heavy lifting” Teeguarden is asking of it. Teeguarden has, if not misused it, at least stretched it beyond its current capabilities.
Despite Teeguarden’s abundant confidence, there is nothing clear cut about his research. In fact, several leading BPA researchers have penned a highly critical dissection of Teeguarden’s study–including a rejection of its approach, its choice of sources, and its validity–that has been accepted for publication by the journal that published the study in the first place.
If you’ve made it this far–despite the total absence of puppies–and are wondering why I’ve devoted so much space to this issue, it’s due to this latest work’s pedigree. A government-funded study performed by government scientists in government labs and involving the DOE, the CDC and the NCTR is bound to get a lot more attention than a smaller academic study, especially given its dramatic conclusions. Even so, the study provides little for industry to sink its teeth into–though the tin can lobby is surely trying.
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