With a stroke of his pen, Boston Mayor Martin J. Walsh gave cause for celebration to environmentalists and drew grumbled complaints from food retailers. The ordinance he signed into law, which bans Boston stores from giving out single-use plastic bags beginning December 2018, has been hailed by many environmental groups as a significant and necessary step in Boston’s continuing green push. Simultaneously, it has been panned by those in the food industry as misguided and potentially harmful.

The ordinance, which Boston’s City Council passed unanimously in late November and Walsh signed Dec. 17, 2017, leaves consumers with a few options when it comes to toting their groceries: They can pay a five-cent fee for a paper, handled bag or a thick, compostable plastic bag; they can ask for a free paper bag without handles; or they can bring a reusable bag to the store.

Kirstie Pecci, a senior fellow at the Conservation Law Foundation, said removing plastic bags from Boston’s waste stream is a needed step toward Boston becoming waste neutral, something Walsh has said is a primary goal for the city.

“If you look at plastic bags by weight, it’s not a huge development,” Pecci said. “However, if you look at how plastic bags operate in the environment and the negative impact they have on recycling programs, getting them out of the system is extremely important.”

She presented throwaway plastic bags as a litter problem, a culprit in jamming recycling equipment and a type of plastic that can’t easily be recycled.

A few plastics — plastics with resin types 1, 2 or 5, which are not used to make single-use bags — can be commercially recycled at a net gain. Only 5 percent of single-use plastic bags get recycled. And that’s a best-case scenario, Pecci said. The other 95 percent end up in landfills or incinerators, and both scenarios create toxic pollutants “you wouldn’t want to live near.”

“All the way through, from the production of plastic bags to the recycling of them to the disposing of them, it’s all highly polluting,” she said. “We should be looking to get rid of these.”

A senior vice president of the Massachusetts Food Association, a trade association that represents many Boston grocery stores and opposed the ordinance, said the measure is disruptive to recycling systems already in place and is bad for consumers. The vice president, Brian Houghton, also questioned the wisdom of pushing paper bags over plastic ones.

Houghton said claims that the ordinance will help the environment may be misguided.

“Is paper better for the environment?” he said. “Paper bags are heavier, so you’re going to need more trucks to transfer them. They cost more to make. Paper mills aren’t the best thing for the environment, and if you’re going to make more paper bags, there’ll be more use of paper mills spewing out pollutants.”

Pecci said it may be Houghton and other business advocates, though, who are misguided. A study — conducted by the Franklin Associates consulting firm for The Plastic Foodservice Packaging Group — concluding plastic is greener than paper has been categorically refuted. A letter from more than 40 environmental and civic groups urging City Council to pass the ordinance cites a Mass Green aggregation of scholarly and world government studies that debunks the notion of plastic being environmentally healthier than paper.

“The [Franklin Associates] study ignores the health effects of polystyrene [plastic],” the Mass Green report says. “Unlike paper, it never decomposes into the soil. Rather, it just breaks down into smaller bits, microplastics.”

Because of plastic’s toxicity — another characteristic it does not share with paper — this longevity poses “extensive consequences for the food chain.” This, in effect, flips the script on any concern about paper being “heavier” than plastic, the study says.

Houghton also abstractly references pollutants “spewed” by paper mills and doesn’t address pollution caused by plastic production. The aforementioned letter, though, does address that: More than 1.6 billion gallons of oil are used to produce plastic bags each year; bags used in Boston alone produce over 9,532 metric tons of carbon dioxide yearly.

Houghton also said the ordinance interferes with his constituent stores’ recycling programs for plastic bags — he said they send whatever bags they collect to construction companies to be used in the production of plastic decking.

“I don’t know what they’re going to do with these programs now,” he said. “They’re going to have to be altered. You can’t mix compostable bags in with plastic bags to have them remade into something like decking, or new plastic bags. Maybe they’ll just stop collecting plastic bags at all, which would be very harmful.”

Proponents of the ordinance counter this by saying the objective is not to push compostable or paper bags, but to push reusable bags and cut down on all bag disposal.

Shifting consumers toward reusable bags may not be not that far-fetched. There’s a success story just across the Charles: Cambridge, which enacted a similar ordinance in March 2016, has seen a 50 percent reduction in the use of any single-use bag since then, according to Michael Orr, the recycling director of the Cambridge Public Works department.

Orr said the ordinance has been a success for Cambridge in promoting reusable bag use and is indicative of potential future success for Boston.

“When you put a charge on bags, it changes the behavior of the consumer,” Orr said. “The behavior that changes is the frequency of them bringing reusable bags. In Cambridge, our huge increase of reusable bag use meant there were fewer plastic bags that needed to be recycled.”

Orr proposed that reducing the need for recycling is perhaps more important than recycling itself moving forward.

“You talk about the mantra of ‘reduce, reuse, recycle’ — ‘recycle’ falls at the end of that, not at the beginning,” Orr said. “The goal of the program is to reduce single-use bags, to reuse bags, which we’re seeing people do, and then recycle, if you have to use a single-use bag.”

The Husky Environmental Action Team (HEAT) has been advocating for the elimination of single-use plastic bags, and they’ve found success: Northeastern stopped using such bags at its on-campus dining locations long before the City Council vote, beginning in August 2017. HEAT vice president Max Wagner said this saves more than 200,000 bags annually from one eatery, Outtakes, alone.

A Northeastern Dining employee, who wished to remain anonymous to protect his job, said the new, reusable bags used in Outtakes are an improvement.

“You can fit more things in these bags, they’re a lot more convenient,” the employee said, as a cashier nearby held up one of the purple bags for show. “It doesn’t matter what we [the employees] want, it’s what the students want. And it’s better for the environment. Students bring these [bags] back, it’s like recycling.”

The employee added that it’s been hard to gauge how many of the reusable bags are needed, resulting in stretches of time in which the store awaits a shipment and students are left without any bag to carry their items.

HEAT is also advocating for the replacement of paper towels with hand dryers, composting and eliminating plastic single-use bottles on campus.

“I’d like to think the [city-wide] bill will encourage everyone to reconsider how wasteful they’ve been in the past,” Wagner, a third-year finance major told The News last month.