Plastic bag bans may lead shoppers to buy more plastic

Many cities around the world have set plastic bag bans or have introduced fees to reduce the amount of plastic usage. That’s because plastic is notoriously hard to get rid of in landfills, and micro- and nanoplastics have contaminated rivers, seas and can be found even in our bodies.

Yet even though these policies are meant to reduce plastic use, they may end up simply causing more plastic bags to be purchased instead, as a new study by a University of Georgia researcher, published in Environmental and Resource Economics, details.

Plastic shopping bags are seen as single-use items. They often end up being reused as bin liners for small trash cans. When people end up with fewer plastic bags from their shopping trips because they now carry a fee or are banned altogether, they end up buying multipacks of garbage bags as bin liners, defeating the purpose of the plastic bag bans or fees altogether.

“We know there is a demand for using plastic bags, and we know, if these policies go into effect, some bags will disappear or will become more costly to get,” says Yu-Kai Huang, a postdoctoral researcher at the UGA Warnell School of Forestry and Natural Resources. “So, we wanted to see the effectiveness of this policy in reducing bag usage overall.”

Studies conducted earlier have assessed the effect of bag bans on plastic consumption, but not the combined effects of fees or a bag ban. According to a news release, Huang, an environmental economist, “used a new way to calculate the effect of either policy while also accounting for variables such as residents’ income levels and an area’s population density, both of which influence the amount of trash generated in a community.”

Huang’s study employed retail scanner data and a general synthetic control method, finding “that both types of [carryout grocery bag] regulations are associated with significantly higher plastic trash bag sales.”

Knowing that plastic grocery bags are often reused in the home, Huang and professor Richard Woodward of Texas A&M University assessed plastic bag sales in counties with bans or fees in place. They compared this data with that from counties without these policies in place. In order to leave out shoppers crossing over to neighbouring counties to avoid the policies, they chose counties far away from each other to study.

The result of their assessment found that California communities with bag policies saw sales of 4-gallon (15 litres) trash bags increase by 55 percent to 75 percent. Meanwhile, sales of 8-gallon (30 litres) trash bags increased by 87 percent to 110 percent. “These results confirm previous findings on bag bans and provide new evidence on bag fees,” the authors note.

Even though sales of small garbage bags increased after bag bans or bag fee policies, sales of 13-gallon (49 litre) trash bags – the size of kitchen trash cans – were almost the same. This further underscored the double life of plastic grocery bags, Huang says.

“Carryout grocery bags were substituted for similar sizes of trash bags before implementing the regulations,” he wrote in the paper. “After the regulations came into effect, consumers’ plastic bag demand switched from regulated plastic bags to unregulated bags.”

When the side effects of plastic bag bans or fees were calculated according to weight, purchases of 4-gallon trash bags increased consumption by between 30 and 135 pounds (approx 14 to 61 kilograms) per store per month. The sales of 8-gallon trash bags created an additional 37 to 224 pounds (approx 17 to 102 kilograms) of plastic per store per month.

But, Huang noted, bag bans or fees could make a dent in plastic waste among high-volume stores. The study found that if a store generated at least 326 carryout plastic bags a day—about 9,769 per month—the policy would end up sending less plastic to the landfill.

It’s important for policymakers to understand the unintended consequences of plastic bag bans or fees before implementing them, Huang says. And, if residents are reusing bags for trash cans, it can also affect the overall use.

“There’s no clear answer for this,” he says. “Whether the provided free carryout grocery bags are reused is a key to determining the overall effectiveness of the related grocery bag policies.”