Reusable bags are often hot topics of discussion, as they became again recently when professors of law Jonathan Klick and Joshua Wright from the University of Pennsylvania and George Mason University, respectively, released a research paper titled "Grocery Bag Bans and Foodborne Illnesses." The study looked at emergency-room statistics in San Francisco County and found a 46% increase in deaths from foodborne illnesses after the county banned plastic bags in 2007, which the authors implies correlates to an increase of 5.5 deaths year.
Is this the first time we've seen reports trying to link reusable bags to foodborne-illnesses? No. But as with previous studies on this topic, the most effective way to respond to them is using sound science. That's what Tomás Aragón, Health Officer of San Francisco, did to respond to the Klick and Wright study. In a memo composed in response to the study, Aragón notes that "Based on review of this paper, and our disease surveillance and death registry data, the Klick & Wright's conclusion that San Francisco's policy of banning of plastic bags as caused a significant increase in gastrointestinal bacterial infections and a '46 percent increase in the deaths from foodborne illnesses' is not warranted." Aragón also reminds us of several important research considerations, including:
Law professors and epidemiologist use different study designs to infer causality.
Research studies with alarming conclusions can alarm the public, so be cautious.
Collaborating with experts in other disciplines often leads to better science.