气候变化领域集成服务门户

It’s not easy to create a new habit like bringing your own bags to buy groceries, even for someone like Dan Donovan, spokesman for Pittsburgh-based Giant Eagle grocery chain. 

“I can t tell you the number of times that I ve walked into a Giant Eagle and thought ‘shucks, I forgot my bags back in my car,’ ” he admitted.

In January, Giant Eagle made an effort to help people remember by providing fuel perks to customers who brought their own bags from home, as part of a goal to eliminate single-use plastic bags in its stores by 2025. A pilot program also removed them from checkout counters at the Waterworks location in Pittsburgh, at a store near Columbus, Ohio, and at multiple locations in the Cleveland area. 

“We actually helped eliminate 20 million single-use plastic bags from entering our landfills or otherwise cluttering our communities,” Donovan said. “So we were very excited about that.” 

Things changed in February and March, as COVID-19 hit the region. There was uncertainty about how the virus spread, and questions about the safety of reusable bags. 

“All of us were just uncertain. We were just concerned, and we were scared, to be quite frank,” Donovan said. “We brought the plastic bags back in and we asked customers not to bring in their own reusable bags.” 

Other supermarket chains did the same. States including California, New York and New Hampshire backed off bans on certain single-use plastics, as did many cities like Philadelphia and Chicago. Reusables were being associated with the possible spread of the virus, while single-use plastics seemed cleaner and less likely to carry disease. 

This general idea by many people was not an accident, according to Robert Hale, environmental chemistry professor at the Virginia Institute of Marine Science.

“There was a fairly organized campaign among plastic manufacturers and the related industries to basically infer that reusable plastics did indeed present some sort of COVID- related health risk,” Hale said.

Hale points to a well publicized letter by the Plastics Industry Association, which asked the Centers for Disease Control to speak out against plastic bans as a public safety risk. The letter said reusable bags can carry viruses and bacteria that can spread throughout a store in “study after study after study.” Hale thought this meant there was a basketful of studies, but then he looked into it. 

“Well, yeah, there were three,” he said.

In a scientific opinion piece he wrote in the journal, Environmental Health and Technology, Hale found that none of the studies were specifically relevant to the transmission of coronavirus. 

In one, researchers from Oregon studied the spread of a norovirus from a reusable bag that had been in the bathroom while a person was sick. The food in that bag was later eaten. Hale says here, the food was studied as a transmission route, but not the bag itself. 

The other two studies looked at cross-contamination from bacteria, also not coronavirus, from reusable plastic bags after repeated use.

“I think these studies that are cited point out that there is a potential issue from reusable bags, but it is probably not from COVID, but the fact that you need to wash these things every once in a while,  Hale explained. Don t put your gym socks in with your groceries,” 

In addition to not looking at coronavirus, the studies didn’t look at the outside of a bag, where it could spread throughout a store. “They are not really, truly appropriate to the question at hand.” he said. “But the concept that reusable bags present a hazard because of COVID, it has nothing to do with that.”

The Plastics Industry Association declined to comment for this story. A CDC spokesperson said in an email that they do not have specific guidance on grocery store bags.  

Jodi Sherman with her reusable bag. Photo courtesy of Garrett Sendlewski / Yale University

There is a 2018 study from Loma Linda University School of Public Health where researchers sprayed reusable bags with a surrogate for norovirus, which causes gastroenteritis, or stomach flu, that can come from contaminated food or surfaces. After volunteer shoppers moved through the store, the surrogate was found on the hands of grocery store clerks, on the checkout counter and shopping cart handles. 

When COVID-19 first became an issue, study author Ryan Sinclair used these findings to recommend people stop using reusable bags during the pandemic, and opt for the single-use grocery bags provided at checkouts.

“[Single-use bags] are new, and they didn t transit to somebody s home, and they didn t go in the trunk of your car, and they didn t go on your kitchen counter, and in the grocery cart,” Sinclair said. “So, they re much less likely to have the contamination.”

But norovirus isn’t coronavirus, and transmission through reusable bags is “a very unlikely route of transmission [for coronavirus],” said Dr. Jodi Sherman, associate professor of epidemiology at Yale School of Public Health.

“Single-use or reusable bags are no better or worse for transmission or prevention of transmission of the COVID infection.

Sherman says it was prudent in the early days of the pandemic to limit reusable bags, but now coronavirus transmission routes are better understood. “Single-use or reusable bags are no better or worse for transmission or prevention of transmission of the COVID infection,” she said. 

Sherman is one of more than 115 public health experts, including virologists and food packaging safety specialists, who signed a statement on this issue, which was released by Greenpeace USA. The letter assures retailers and consumers that during the COVID pandemic, reusable bags can be used safely. 

“The bottom line is that there is no study looking at infection transmission of viruses through single-use versus [reusable] bags,” Sherman said. “So really what we have are case reports and case studies, and I know of none that have tied anywhere in the world an outbreak or transmission of SARS-CoV-2 through reusable bags.” SARS-CoV-2 is the name of the coronavirus that causes COVID-19.

Sinclair agrees that there is no data on whether reusable bags spread coronavirus. But he says that doesn’t mean bags people bring from home are totally safe either. With [reusable] grocery bags, you can t rule them out yet,” he said. 

Still, based on mounting evidence that coronavirus spreads mostly through the air, and not surfaces, Sinclair is updating his initial recommendations against reusables, as long as people are careful. “If you re going to use reusable bags, you need to wash your bags,” he said. He also suggests using cloth bags because plastic has been shown to hold onto the virus for up to 72 hours, and cloth is more easily washed. 

While New York continues to delay implementation of its ban on single-use plastic bags, California has reinstated its bag ban.

In Pennsylvania, United Food and Commercial Workers Local 1776 represents more than 20,000 supermarket workers, including cashiers and baggers at Giant Eagle. Its president, Wendell Young, supports efforts to reduce plastic waste. He says the initial fear of resuables spreading coronavirus is now tempered with more information.

“I m okay with customers using reusable bags. We are, as a union, okay with that,” he said. “We just don t want our members handling them because we don t know how they were cared for.” 

Some grocery chains have already started allowing customers to bring in reusable bags again. Giant Eagle plans to officially welcome them starting in September. Customers with reusable bags will be asked to use self-checkouts, and bag their own groceries.