If you own a grocery store, plastic bags have some big advantages. They’re cheap — around two or three cents each, compared to anywhere from six to 12 cents for paper bags. They’re also quick and easy to pack.

But according to Emily Norton, the Massachusetts Chapter Director for the Sierra Club, the problems they create are much, much bigger.

"By 2050, if not before, we’ll have more plastic than fish in our oceans," Norton said. "We put a garbage truck full of plastic into the ocean every minute. [We use] 100 billion plastic bags a year, and the vast majority are not being recycled."

Which is why the Boston City Council passed a proposed plastic bag ban last month. If it goes on the books, single-use plastic bags — the sort you often see sitting in a gutter, or washed up on a beach, or stuck in a tree — would disappear. Instead, stores could sell customers compostable plastic bags, or paper bags with handles, for a price of at least a nickel each, as well as heavier reusable bags.

"To have Boston take this vote, the biggest city in Massachusetts, the biggest city in New England, that’s really powerful," Norton said. "This’ll be the biggest city on the east coast to ban plastic bags."

Boston would also be the 60th Massachusetts community to take this step — but it’s not official just yet. When the ban was first passed by the Boston City Council, Mayor Marty Walsh expressed concern about the cost to seniors.

If he doesn’t sign the ban by Monday, it’ll become law anyway. Then again, Walsh could veto the measure — sending it back to the City Council for a possible override next year, and making the Massachusetts Food Association very happy in the interim.

"The way it’s written," said MFA senior vice president Brian Houghton, "we are in opposition to it."

Houghton notes that the proposed ban has a major loophole: stores could still provide paper bags without handles free of charge. He thinks they would — and that that’s the choice customers would ultimately make.

"They're going to just take a non-handled paper bag for free," Houghton predicted. "And that’s not really the best thing for the environment to push people towards paper."

And, he added, not the best thing for Boston’s grocers.

"Their costs are going to increase," Houghton said, noting that the supermarket sector is already grappling with rising health care costs and increases in the minimum wage. "Paper bags are heavier, they’re more expensive to create than plastic bags, they’re more expensive to transport."

Ideally, Houghton said, he’d prefer a statewide ban that nudges people toward reusable bags by charging for both paper and plastic.

The Sierra Club’s Emily Norton wants a statewide ban, too. But she'd like one that nixes plastic altogether — and as she tells it, Boston’s example could help make that happen.

"With everything going on in the country right now, people are looking for leadership, states are looking for leadership, cities are stepping up to lead on many issues, certainly on the environment," Norton said. "So it would make sense that Boston would be a leader in this effort."

So if Boston does ban plastic bags, how tough would the adjustment for retailers actually be?

Inside Tropical Foods, a bustling supermarket in Roxbury’s Dudley Square neighborhood, co-owner Ronn Garry predicted that his store would manage.

"What doesn’t work for our customers a lot of time is paper, because they’re using public transportation and that breaks easily," Garry said.

If the ban passes, he added, "We’re going to have to go to some form of [reusable] plastic. And it’ll be a learning curve. People are gonna have to remember to bring it to the store with them, but they’ll get used to it."

One customer we spoke with was grudgingly accepting when asked about the ban, saying, "Some things, you just can't control." 

Another, though, was far more enthusiastic.

"I support it because I bring reusable bags," she said. "I don’t like plastic."

A sentiment that’s increasingly widespread, whether Boston’s ban becomes law or not.