Friday, January 16, 2009

Green: BPA, revisited

Remember my big, long post on bisphenol-a a little over a year ago? Remember how I got my own troll? We laughed, we got indignant, we closed comments. Good times.

Mostly I was amused that an industry talking head was so intent on yelling me down. It seemed like a lot of effort to deal with a very small time blogger's take on the issue. At the time, I argued as best as I could with the information I had; I knew that the reports he cited were spinning the data and that there was much more out there to vindicate my position, but I didn't have the time or resources to track it down right then.

And then earlier this week, I found Trillian's copy of Fast Company sitting on my chair. (When she has airline miles that are about to expire, she gets magazine subscriptions. We also get The Economist and Martha Stewart Living. I can create festive decorations out of depressing retirement account statements!) It was open to an article, "The Real Story Behind BPA."

It took me a while to get through the whole thing. The article is dense with information, and I had to put it down every time my blood pressure rose too much. But there it was, the information I knew existed. If you get the chance, go read the whole thing. Really, it's worth the time! But let me highlight some of the points I wish I'd had at my fingertips last year.

Issues of methodology:
  • Toxicology. In this model, the issue is to define the threshold of significant harm. Experiments in this vein feed huge doses to the test subjects, seeking the point at which organ failure, cancer, and other things (like death) happen. The current acceptable level of BPA has been set using this model. If you go back to my old post, you'll also see that this is the model referred to by my troll.
  • Endocrinology. This model focuses on changes caused by small doses of chemicals that mimic hormones. And since BPA has recognized estrogenic properties, it seems reasonable to expect this to be the accepted model of study. But it's not, at least as far as government studies are concerned.
Studies:
  • "Of the more than 100 independently funded experiments on BPA, about 90% have found evidence of adverse health effects at levels similar to human exposure. On the other hand, every single industry-funded study ever conducted -- 14 in all -- has found no such effects."
  • The first studies of BPA's effects at low doses were inspired by multiple experiments in which unexpected results were traced back to the use of polycarbonate items (flasks, petri dishes, cages).
  • vom Saal examined the interaction of BPA with human blood and realized that it needed further study. In an experiment where he fed pregnant mice doses of BPA "25,000 times lower than the EPA's toxic threshold," male offspring had enlarged prostates.
  • vom Saal's findings have been replicated multiple times by other scientists. Nonetheless, industry often refers to his experiment as unreplicated, a blatant lie.
  • "Others have found impacts on sperm production, testes development, and mammary-gland tissue, as well as behavioral disorders including hyperactivity, aggressiveness, and impaired learning."
  • Tyl performed two experiments, the most commonly cited in the industry, claiming BPA as safe. In the first experiment, she used a strain of rats (CD Sprague-Dawley) that "can withstand a dose of synthetic estrogen more than 100 times greater than what a female human can tolerate." In the second, she used mice, but they were fed a type of food shown to "mask the effects of estrogens like BPA." Even then, her results show male mice with enlarged prostates.
  • Government reports have officially based on reviews of the available literature. But a closer look at these reports shows that these are not even close to being unbiased. There's a big, long explanation in the article about how much of this work was outsourced to a consulting firm that, conveniently, does a lot of industry work and has frequently had questionable conflicts of interest.
And if all that doesn't make your head spin, a mention that one such consulting firm has offerred to help Dupont defend PFOA (the potentially nasty chemical in non-stick surfaces) makes me feel pretty certain there's a similar story there.

I'd be lying if I claimed not to get some enjoyment out of saying, "I told you so." (Trillian would call me out on that immediately. And it's not like I'm saying it to my usual readers--we'll see if the troll returns.) But this is one time when I wish I hadn't been quite so right, because the whole issue is quite disillusioning and a bit scary.

Time to go clean out the pantry and try to figure out alternatives to various canned items.

4 comments:

Bea said...

Wait. Air miles can expire?

Mouse said...

That may just be in the States. Here, each airline has their own program and they frequently attach an expiration date to their miles. The mileage deals are never good enough to make us fly with one airline exclusively, so we haven't been using them for travel.

kgirl said...

Can you teach me how to do those crafts?

As you know, BPA has been banned to an extent in Canada, but the fact that it is still in the cans freaks me out.

Lisa b said...

yeah, as we like to say in my office in general about any env issue- it really is much, much worse than it is being portrayed.

we are a fun bunch.