As more cities and states ban plastic shopping bags and single-use plastic items like straws, we’re starting to see evidence that the policies might be having an effect quite the opposite of what their originators intended.  

The idea, of course, is to keep plastic waste out of the waterways and stop it from eventually ending up in the ocean, where tens of thousands of tons of trash now cover hundreds of thousands of square miles. But as this article explains, a study in California—the first state to issue a statewide ban on bags—shows that although people do in fact use fewer plastic bags to carry their groceries, they’re actually purchasing more of them to use for other purposes, like lining their trash bins and picking up after their dogs. Because they can’t reuse the flimsy shopping bags as they once did, they’re buying heavier ones, resulting in an overall increase in plastic. “About 30% of the plastic that was eliminated by the ban comes back in the form of thicker garbage bags,” says Rebecca Taylor, the economist who conducted the study.  

In addition, the article notes, people are replacing the plastic shopping bags with paper ones, which—even though they’re biodegradable—in some ways have a worse effect on the environment: “They require cutting down and processing trees, which involves lots of water, toxic chemicals, fuel, and heavy machinery. While paper is biodegradable and avoids some of the problems of plastic, Taylor says, the huge increase of paper, together with the uptick in plastic trash bags, means banning plastic shopping bags increases greenhouse gas emissions.” 

And reusable cloth bags could be even worse. The article cites a British study that says a cotton bag would have to be used 131 times to make it less damaging to the environment that a single-use plastic bag. It also mentions a Danish study that says—taking into account water use and pollution from growing and transporting cotton—“you would have to use an organic cotton bag 20,000 times more than a plastic grocery bag to make using it better for the environment.”