A group of Portland residents has proposed what would be the strongest municipal restriction on the sale and use of controversial outdoor bug and weed killers in Maine, and city councilors will begin discussing the plan Wednesday.

A residents’ group called Portland Protectors submitted the three-page ordinance proposal in August, hoping to prod city officials to address what they see as a mounting threat to humans, animals, beneficial insects and the environment as a whole, including Casco Bay.

Meanwhile, as Portland officials review the citizen proposal, city officials across the Fore River in South Portland are developing a proposal to restrict pesticides that they hope to present publicly in November.

A major concern among pesticide opponents is glyphosate, the active ingredient in Monsanto’s broad-spectrum herbicide, Roundup. While the U.S. Environmental Protection Agency says it’s “safe” when used correctly, the World Health Organization’s International Agency for Research on Cancer in March classified it as “probably carcinogenic.”

The Portland pesticide proposal goes beyond weed and bug killers to include synthetic lawn fertilizers, which some believe run into nearby sewers and streams, contribute to the acidification of Maine’s coastal waters and harm the plant and animal species that live there.

“This proposal pushes the council into action,” said Avery Yale Kamila, a founder of Portland Protectors.

The City Council’s sustainability committee is set to take up the proposal at 5:30 p.m. Wednesday in Room 209 of City Hall.

The proposal would prohibit the sale and use of synthetic fertilizers and pesticides, other than those allowed in organic farming or classified by the EPA as exempted materials, such as cedar oil and sodium lauryl sulfate.

The proposal also would require Portland to establish an ongoing community education campaign and would force commercial pesticide applicators to be certified in organic land care management, in addition to state-required licensing and training.

It contains no blanket exemptions, but would allow the council to grant seven-day emergency waivers to address public health or environmental threats, such as mosquitoes and other infestations, with the least-toxic material available.

“The presence of weeds, vegetative overgrowth and common fungal diseases encountered in the usual course of landscape management shall not constitute an emergency,” according to the proposal.

Twenty-five Maine communities, including Ogunquit, Brunswick, Rockland, Wells, Lebanon and Waterboro, have pesticide-control ordinances that ban or regulate the type or method of pesticides used in municipal, agricultural and forestry applications, and near drinking-water supplies.

Ogunquit is the only town to extend its ordinance broadly to include all private property owners, but it’s not an outright ban. It allows restricted pesticides to be used to kill noxious or invasive plants, such as poison ivy, and to address health and safety threats, such as disease-carrying insects.

Takoma Park, Maryland, was the first U.S. city to ban the use of “cosmetic lawn pesticides” in 2013. Some provinces and hundreds of municipalities across Canada have taken similar steps, along with anti-pesticide measures in France, Germany and the Netherlands.

In Maine, the use of various synthetic, natural and organic pesticides is overseen by the Board of Pesticides Control.

Deven Morrill, a supervisor at Lucas Tree Experts, is chairman of the board. Lucas provides a variety of commercial and residential landscaping services, including tree trimming, lawn care and mosquito control.

Morrill said many Maine companies already practice integrated pest management, which aims to use the least amount of the least toxic or environmentally hazardous materials to achieve the best results in landscaping.

“We offer both organic and conventional programs and we’re happy to do either,” Morrill said. “We applaud citizens groups for taking on this subject. It can be an emotional topic for some people, but it can be an educational opportunity as well. It allows us to explain what we do and why we do it.”

Morrill said any pesticide regulation must weigh the benefits and the costs of restricting use. Hindering the ability to combat the emerald ash borer or the Asian longhorned beetle, for instance, could devastate Maine’s forest industries, he said.

Portland city staffers are reviewing the citizen-proposed ban and are expected to issue recommendations in the coming weeks, said Councilor David Marshall, chairman of the sustainability committee.

However, it probably will be several months before some form of the proposal goes before the full council, especially with council elections coming in November.

“A lot of these things can be tough to implement,” Marshall said. “At this point it’s very preliminary. There will be plenty of opportunity for the public to comment.”

South Portland city staffers have been working on a pesticide ordinance for a few months and expect to present a draft to the City Council in November. They’re talking with proponents of a ban and various people who would be affected by it, including business owners and applicators, said Julie Rosenbach, South Portland’s sustainability coordinator.

“It’s extremely complicated, but it makes it very interesting,” Rosenbach said.

“I want a very strong ordinance, and part of that is going to be making it a very feasible ordinance.”