It’s everywhere — packing peanuts, ice chests, beach toys, dock floats, mooring buoys and fish trays.

But the proliferation of Styrofoam may end soon in San Francisco under legislation by Supervisor London Breed, who is proposing the most extensive ban on the product in the country.

“The science is pretty clear: This stuff is an environmental and public health pollutant, and we have to reduce its use,” Breed said.

Industry representatives counter that Styrofoam, technically known as polystyrene foam, is still the most reliable and cost-effective packaging product available. And they say Breed and the city’s Department of the Environment, which helped craft the legislation, overstate its negative impacts.

“In reality the city of San Francisco is not going to be helping the environment. They are just going to appear to be helping the environment,” said Betsy Steiner, executive director of EPS Industry Alliance, which represents the interests of foam transport packaging.

The California Grocers Association has also expressed opposition to the legislation. “Grocers need to ensure we can provide safe and quality food before making any packaging changes,” Dave Heylen, a spokesman for the group, said in an email.

Pluses and minuses

Polystyrene is an abundant, cheap and lightweight packaging product. It’s used to send everything from flowers to furniture and medicines that need to be stored at a certain temperature. Unlike some replacement materials, it doesn’t disintegrate if it touches water.

But it takes centuries to decompose, clogging landfills and, when it gets into the water, contaminating the food chain and ecosystem. The preamble to Breed’s legislation ticks off a list of polystyrene’s problems. It “has been linked to cancer as well as reproductive and developmental disorders,” it “threatens the entire food chain,” and it constitutes a “significant source of litter on San Francisco’s streets, parks, and public places.”

Steiner, with the industry alliance group, counters that the city is “picking and choosing numbers to make the problem look like it’s bigger than it is.”

Breed’s legislation builds off San Francisco’s decade-old ban on most foam food containers. Since then, more than 100 cities have enacted laws restricting the sale of foam products, and companies like Jamba Juice and McDonald’s have also phased them out.

Seattle has the most expansive ban on polystyrene foam. Since 2010, it has prohibited the sale of meat and fish in foam containers. Breed’s legislation goes even further by also banning polystyrene beach toys, dock floats and mooring buoys, as well as packaging products, said Russell Long, president of the nonprofit Sustainable San Francisco.

San Francisco’s Department of the Environment will be responsible for enforcing the legislation. It would have the authority to fine companies that don’t comply.

Creating ‘a ripple’

Long hopes San Francisco’s legislation is the first step in getting a ban enacted statewide. “You start getting some momentum on a local level like this and you create a ripple that other cities and counties follow and before long states as well,” he sad. “That’s the goal for the legislation.”

Industries that rely on polystyrene are fighting back. Last year, the Restaurant Action Alliance, polystyrene manufacturers and recyclers sued to halt New York City’s 2014 ban on Styrofoam food containers. A judge agreed, saying the city disregarded evidence that it could save $400,000 a year by recycling the material.

San Francisco began recycling large pieces of polystyrene six years ago. Recology, the city’s garbage and recycling collection firm, uses a machine that densifies the material and turns it into a hard paste, which it then sells for use as paint trim. But project manager Robert Reed said Recology doesn’t recycle polystyrene left in recycle bins and most still ends up in the garbage — or the water.

At a Recology facility in the Bayview where building contractors dump their waste, he picks up a crumbling piece of polystyrene. Tiny droplets the size of peppercorns blow away with a light gust of wind.

“The fish — they see that and they think it’s food. It looks like fish eggs,” Reed said.

Steiner, with EPS Industry Alliance, said the city could do more to try to recycle the product. She said 52 communities in California have a curbside program for dropping off polystyrene for recycling, including Sacramento and Los Angeles. San Francisco is not one of them.

While Breed’s legislation is likely to pass, a looming question is to what extent and when it will be implemented.

The ordinance gives the Department of the Environment the power to make exceptions for categories of polystyrene use. Department spokesman Guillermo Rodriguez said it would probably allow companies that ship medicines at prescribed temperatures to continue using polystyrene for at least a few more years.

The legislation will not impact packages with polystyrene foam sent from out of state. Amazon packages sent from Portland, Ore., to San Francisco, for example, could still include polystyrene.

Grocers seek waiver

The California Grocers Association has also said it will ask the department for a waiver to continue using polystyrene for meat and fish packaging.

“Our request is the city allows grocers substantial time to identify food-packaging options that are safe and reliable as well as acceptable to the city,” Heylen said in an email.

Sustainable San Francisco opposes such a waiver, saying grocers in Seattle have already found a viable alternative.

Breed said the Department of the Environment will have the final say. But she emphasized that the legislation is long overdue.

“We should have made plans years and years ago,” she said. “This is about the fact that we have the technology to do better and we should be doing better.”

Emily Green is a San Francisco Chronicle staff writer. Email: egreen@sfchronicle.com

Twitter: @emilytgreen