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A Teachable Moment About Plastic Bag Bans

Originally posted on Huff Post Green

A friend emailed me asking my opinion on a paper that quantifies the effect of plastic bag bans on emergency room visits for infectious intestinal diseases. I'll let the author's figures tell the story here.

What might account for this effect of the apparently increasing number of ER visits in San Francisco County as a function of a plastic bag ban? Well, the authors cite another study that shows that E. coli — a bacteria that can cause diarrhea and vomiting and sometimes death — was found in 8 percent of reusable bags examined and this might be explained by the twin facts of people not using separate bags for meats and vegetables and that bags were rarely (or never) washed between uses.

But wait, there's more! The authors go on to estimate that the bag ban is responsible for an extra 5.5 deaths in the San Francisco County that result from foodborne illnesses. Scale this up to the nation, and there could (and I emphasize could) be a substantial number of extra deaths that one might (and I emphasize might) attribute to plastic bag bans.

OK, so you can imagine what the conservative bloggers are saying about this (indeed, the friend who pointed this paper out to me is a conservative blogger!). My immediate response was that this looked potentially important and needs to be replicated elsewhere.

However, I was somewhat shocked when my less conservative friends started firing off unscientific responses about those who oppose bag bans. These included: the people that wrote the report were not scientists (true, they appear to be lawyers and economists — so what? Their data should be evaluated on the basis of it, not on the author's academic qualifications); the report was not published in a peer-reviewed journal (true, it was a research paper from the Institute for Law and Economics at the University of Pennsylvania — ultimately, such studies should be published in peer-reviewed journals because genuine peer-review provides the critical vetting that is essential to have faith in a study); and, the plastics industry supports all those that oppose bag bans (I can't tell if the plastics industry supported these folks, but it is true that the plastics industry has a long history of opposing plastic bag bans). My friends didn't address the data, and it took a lot of prodding to get them to view this as a teachable moment. And oh what a teachable moment this is.

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