San Francisco is expected to take a step closer today to becoming the first city in the nation to charge shoppers for grocery bags with the idea of reducing waste.

The San Francisco Commission on the Environment is likely to approve a resolution urging Mayor Gavin Newsom and the Board of Supervisors to impose a 17-cent fee on both plastic and paper bags, said Mark Westlund, spokesman for the Department of the Environment.

The resolution also calls for an independent study -- requested by Supervisor Ross Mirkarimi along with the mayor -- of just how much the use of disposable checkout bags, including their disposal, costs the city.

The 17-cent fee could be adjusted depending on the results of the study, Mirkarimi said.

Newsom joined Mirkarimi in requesting the study, but a spokesman for the mayor said Newsom hadn't taken a position on imposing the fee.

Even if the commission approves the resolution today, it will be months before it comes before the supervisors for a vote -- and it's likely that it would be amended by then.

"Where the meat of this is going to work out is at the board level, and it's going to be based on the analysis," Westlund said.

Mirkarimi said that the American Plastics Council, which is among the groups that have successfully lobbied to keep such a fee from passing at the state Legislature, also was beginning to work against the local proposal.

"This hype is being generated by the Plastics Council to scare people away from something that hasn't been built yet," he said.

The American Plastics Council and the California Grocers Association oppose the fee.

Tim Shestek, spokesman for the Plastics Council, says that plastic bags - - which make up 90 percent of bags at groceries -- are a valuable commodity used in the production of goods, including composite lumber. Instead of imposing a fee, municipalities should create recovery programs to keep the bags out of the waste stream, he says.

"Whatever happens (today), we're very eager to have a dialogue with the supervisors and mayor's office on different approaches," Shestek said.

Although the fee would be levied on grocery stores -- and perhaps down the road on other businesses including drug stores, newspapers and dry cleaners -- the cost would be passed on to the consumer.

Half of the revenue generated would go to the city for use by the Department of the Environment. Supermarkets would be able to keep up to half of the fee for programs such as providing discounted reusable checkout bags to low-income residents and bags in the produce and bulk aisles that can be composted.

The commission will meet at 5 p.m. in room 416 of City Hall.