The newest front in the war on plastic is coming courtesy of the Sobeys grocery store chain, which will become the first Canadian grocer to end the use of plastic bags. Sobeys said the move will take 225 million plastic bags out of circulation each year at their 255 Canadian locations, and according to the president of the company that owns Sobeys, is due to consumer demand to “use less plastic.”

Many people worry about plastic pollution and it’s a real environmental problem. The question is (as it often is about environmental policies)—will the Sobeys bag ban do anything to significantly impact the problem? And what are the trade-offs?

Writing in the Globe and Mail, Bjorn Lomborg (often called the skeptical environmentalist) points out that most of the world’s plastic pollution problems aren’t coming from developed countries such as Canada. In fact, less than five per cent of land-based plastic waste in the ocean comes from OECD countries. Moreover, half of the world’s plastic waste comes from four countries—China, Indonesia, the Philippines and Vietnam.

Lomborg observes that despite China’s 2008 ban of thin plastic bags, China still contributes more than an estimated “27 per cent of all marine plastic pollution originating from land.”

And yet, as with Canada’s small contribution to global greenhouse gas emissions, many people argue we have an obligation to reduce our contribution to plastic pollution. Prime Minister Trudeau recently said Canada will ban some “single use” plastics by early 2021, including “straws, bags and cutlery.”

But will it do any good?

Lomborg cites a 2018 study by the Danish Ministry of Environment and Food, which looked not only at plastic waste but also climate-change damage, ozone depletion, human toxicity and other indicators. The study found that an organic cotton shopping bag must be reused 20,000 times before it will inflict less environmental damage than a plastic bag. Yes, 20,000 times.

And there are downsides to using reusable bags. A 2010 study by Loma Linda University tested reusable bags and found that “large numbers of bacteria were found in almost all bags and coliform bacteria in half. Escherichia coli were identified in 12% of the bags and a wide range of enteric bacteria, including several opportunistic pathogens. When meat juices were added to bags and stored in the trunks of cars for two hours, the number of bacteria increased 10-fold indicating the potential for bacterial growth in the bags.” Worse yet, research indicates that people rarely wash their reusable grocery bags, having left them culturing bacteria in the car trunk for days.

And eventually you run into the fact that humans find plastic bags convenient and desirable. As Lomborg notes: it’s one thing to ban something, it’s another thing to have the outcome you expect. “A new study shows California’s ban eliminates 40 million pounds of plastic annually,” he writes. “However, many banned bags would have been reused for trash, so consumption of trash bags went up by 12 million pounds, reducing the benefit. It also increased consumption of paper bags by twice the saved amount of plastic—83 million pounds. This will lead to much larger emissions of CO₂.”

Banning plastics is a feelgood gesture in response to a genuine concern about ocean pollution. But plastic bags aren’t the problem. The real problems, mainly the lack of widespread sanitary and fishery waste disposal in developing countries, are more complex and won’t be helped by virtue-signalling from Sobeys or anyone else.