Totes Dangerous, Ctd

Ramesh recently worried about the health consequences of banning plastic bags:

Jonathan Klick and Joshua Wright, who are law professors at the University of Pennsylvania and George Mason University, respectively, have done a more recent study on the public-health impact of plastic-bag bans. They find that emergency-room admissions related to E. coli infections increased in San Francisco after the ban. (Nearby counties did not show this increase.) And this effect showed up as soon as the ban was implemented. (“There is a clear discontinuity at the time of adoption.”) The San Francisco ban was also associated with increases in salmonella and other bacterial infections. Similar effects were found in other California towns that adopted such laws.

City officials in San Francisco are pushing back on this research:

In a memo (pdf) released earlier this week, [Tomás Aragón, an epidemiologist at UC Berkeley and health officer for the city of San Francisco] explained that this is an example of the “ecological fallacy.” In order to establish a link between the bag ban and illnesses, the authors would have to show that the same people who are using reusable bags are also the ones getting sick. This study doesn’t do that. Aragón also points out that emergency-room data can be very incomplete—under an alternate measure, there’s been no rise in E. coli at all.

Aragón also offers an alternative hypothesis for the recent rise in deaths related to intestinal infections. A large portion of the cases in San Francisco involve C. difficile enterocolitis, a disease that’s often coded as food-borne illness in hospitals. And this disease has become more common in lots of places since 2005, all around the United States, Canada, and Europe (for yet-unexplained reasons). “The increase in San Francisco,” he notes, “probably reflects this international increase.”

Previous Dish on the subject here.