[Editor’s Note: On Monday evening at 7, the City Council, meeting in Council Chambers at City Hall,  will discuss a proposed ban on single-use plastic bags.]

If nothing else, the proposed ban on plastic bags has ignited a much-needed public discussion on our environmental impact, with a focus on two issues: Public health and resource management. The most pressing question that arises is this: Do you wash your underwear?

Bag-terial Infection?

On the issue of public health, namely the concern that canvas bags are more likely to spread harmful bacteria, one would think that the most often-quoted study by ban opponents would originate in the work of medical universities, the Centers for Disease Control, or other scientific institutions with an expertise in the epidemiology of disease. But no. The study in question, titled Grocery Bag Bans and Foodborne Illness, was published as a research paper for the University of Pennsylvania Law School’s Institute for Law and Economics by law professors, Jonathan Klick of the University of Pennsylvania School of Law, and Joshua D. Wright of the George Mason University School of Law.

Lawyers!

Epidemiology, along with its associated statistical methodologies, is a notoriously difficult discipline. The task of proving a causal relationship between two variables is most commonly reduced to identifying a potential correlation, as was well drilled into me in my university epidemiology and statistics classes. But as we know, correlation does not prove causation. While the paper does highlight an interesting correlation between plastic bag bans in, for example, San Francisco, and a rise in E.Coli admissions at the hospital, the study does not prove that the former caused the latter. This isn’t to glibly dismiss the paper without consideration, but to suggest that this sort of research is merely the first step in a long line of research needed to fully clarify the exact nature, if any, of the relationship between plastic bag bans and disease. A single study does not a foundation make, as anyone who pays attention to the metamorphic advice from the nutrition industry can attest.

In any case, the authors themselves acknowledge an obvious solution to the potential problem: Wash the bags. But Reason magazine’s Katherine Mangu-Ward, whose blog post was cited by John Kuechle in a recent essay here at TFPO, raises the crux of Professors Klick and Wright’s contention: “Washing your bags reduces the risk, but let's be honest. Who does that?”

Alas, the professors note that “…97 percent of individuals indicated they never washed their reusable grocery bags.” They further conclude that “washing such bags will, itself, have negative environmental consequences through excess water use. Further, the detergents necessary to clean the bags add to the environmental costs, as does the use of water hot enough to kill the bacteria.”

The detergent and water use concern, though important, is not entirely germane, given how much laundry we already do. To repeat my earlier question: You wash your underwear, don’t you? And your bath towels?

Who Let the Cotton Out of the Bag?

Next is the concern about the total amount of resources used in the fabrication of plastic versus, say, canvas bags. The study Life cycle assessment of supermarket carrier bags: a review of the bags available in 2006 by the U.K. Environment Agency, yields interesting numbers. A cotton bag would have to be reused 131 times to achieve the environmental impact a single plastic bag used once. If the plastic bag is used three times, we would have to reuse the cotton bag 393 times. Putting that into perspective, if you were to use that cotton bag once a week, you would need 2.5 years to achieve the impact of a plastic bag used once, and 7.5 years to match a plastic bag used three times. If you use that canvas bag more than once a week, however, the total number of years needed to match a plastic bag would, obviously, be lower. The key is this: It is entirely possible to use a canvas bag for many, many years and well exceed the number of uses required to match the environmental impact of a plastic bag. I suspect that my bags have been in service for at least seven years, and they are fit to serve for many years more. The requirement that a canvas bag be reused 131, or 393, times is hardly unachievable.

By periodically, but not obsessively, washing canvas bags, the potential risk of infection is reduced. Also helpful: Washing fruit and vegetables before eating. Separating bags by function – I have bags for produce from the farmers market and others for packaged products from my grocery stores – is another useful tactic. Bags that only hold packaged goods that do not have the potential for transmitting disease, such as produce and meats, do not need to be washed nearly as often as bags intended for perishable food items. It is entirely possible to maximize the utility of canvas bags in a way that, in the big picture, results in less of an impact on the environment – something that is increasingly urgent as the world’s population touches on a staggering 7 billion.

Oh, Behave

Whether plastic or canvas, this much is clear: Each type of bag entails a mix of tradeoffs, habits and consequences in terms of environmental impact. As resource-intensive as canvas bags can be, plastic bags pose a problem not only in terms of their production and disposal, but the fact that they are part of a littering problem contextualized by the greater problems (e.g. pollution, health hazards, and ecological destruction) posed by plastics in general. (Visit the Plastics Pollution Coalition for more information.)

Is an outright ban sensible? In part, I tend towards believing that it is because of our association of greater cost with greater value. Consider, by loose analogy, a car. If our Kia is demolished in an accident, the undeniable inconvenience and aggravation would be mitigated by the fact that it was not an expensive car. What if, however, our poor destroyed car had been a Porsche? The value of the loss would be perceived as greater not so much because of brand prestige, but because the car’s quality of engineering, design, materials and production is so much more costly. A bag is not a car, of course, and therein rests the problem. The value-to-cost relationship is not so obvious with bags. Cheap to produce, cheap to use, and easy to discard, plastic bags are symptomatic of a disposable culture that behaves as if our natural resources are limitless, and convenience means never having to clean up after ourselves. The canvas bag, much like any costly item, asks us to maximize its value, through durability and usefulness, on account of its cost.

However, despite a certain crazy visceral appeal underlying an outright ban, for symbolic as well as practical reasons, I ultimately align with Lillia Casanova, the former deputy director at the U.N. Environment Programme's International Environmental Technology Centre in Japan. Writing for SciDev.net, she points out “that plastic bags were made for a purpose, and that the main complaint is against the way that they are used — not their existence.” Indeed, like any technology, plastic bags occupy a precarious balance between benefit and harm. We should not rush to dismiss the benefits.

Although I’m not prepared to rule out a ban, provided it is in the context of broader policy, I do agree in principle with Ms. Casanova that it is “the misuse and improper disposal of plastic bags that is causing harm to the environment, not the product itself,” and that a total ban risks glossing over “the lack of an effective environmental management policy in a given country.”

Perhaps a solution is to have us pay a small charge for each plastic bag we use. Or perhaps a narrower ban, limiting the use of plastic bags to health-sensitive applications, such as meat and produce, would be effective. Whatever choice we make, ban or no ban, we have a responsibility to use our products wisely and in consideration of our relationship to the planet. In short, our behavior has to change.

Frédérik Sisa is the Page's Assistant Editor and resident arts, entertainment, and culture critic. He invites you to visit his blog, Ink & Ashes, and join him on Twitter as he figures out this whole tweeting business.