It’s still too early to predict which side will enjoy ultimate victory in the “should we or shouldn’t we ban disposable plastic shopping bags” war, though both sides can honestly claim to have won recent battles.
In California, a state appeals court upheld San Francisco’s citywide ban on plastic shopping bags. (Of course, this does not negate the possibility that a still-higher court might later rule differently.) Meanwhile, in Colorado, voters in Durango overturned a city council initiative that would’ve mandated a ten-cent-per-bag tax on disposable grocery bags.
The old “paper or plastic?” shopping-bag debate has since yielded ground to the newer “disposable vs. reusable?” argument. The case for taxing or outright abolishing disposable grocery bags almost always rests on environmental or anti-waste concerns: plastic bags fill space in landfills at best, pollute the ocean and kill sea animals at worst; and even for biodegradable and presumably eco-friendly paper bags, there’s no denying that “disposable substances” are inherently more wasteful than “reusable substances.”
On the other hand, there’s an ever-growing body of evidence that unwashed reusable grocery bags become breeding grounds for e. coli and other food-borne contaminants. Indeed, in November 2012, researchers from the University of Pennsylvania and George Mason University published a research paper titled “Grocery Bag Bans and Foodborne Illness,” with an abstract that noted (in a .pdf link):
Recently, many jurisdictions have implemented bans or imposed taxes upon plastic grocery bags on environmental grounds. San Francisco County was the first major US jurisdiction to enact such a regulation, implementing a ban in 2007. There is evidence, however, that reusable grocery bags, a common substitute for plastic bags, contain potentially harmful bacteria. We examine emergency room admissions related to these bacteria in the wake of the San Francisco ban. We find that ER visits spiked when the ban went into effect. Relative to other counties, ER admissions increase by at least one fourth, and deaths exhibit a similar increase.
However, these potential health problems were not raised when opponents of the San Francisco ban made their case to the state appeals court; instead, they argued (unsuccessfully) that the city ban contradicts state regulations on retail stores, and that the city should have done an environmental impact study before implementing the ban.