The science on the key ingredient in the top-selling U.S. weedkiller, Bayer's Roundup, is still in fierce dispute as the company settles thousands of lawsuits claiming health impacts for billions of dollars.

Scientists Split Over Herbicide Risk, Leaving Public in Lurch

Identifying clear guidelines for the level of exposure to glyphosate that could cause cancer or other illness is a contentious business. Monsanto owner Bayer denies glyphosate, the active ingredient in weedkiller Roundup, is a carcinogen. The European Union and the U.S. Environmental Protection Agency back that view. That’s despite a finding from the World Health Organization in 2015 that glyphosate probably is a human carcinogen.

San Francisco city workers use blowtorches to remove grass and weeds from a median on Broadway at Polk Street on Feb. 3, 2020. City workers rely much less on herbicides than they did just five years ago, as health concerns mount.

As Cancer Concerns Lead Cities to Ban Herbicide, S.F. Scales Back Use of Roundup

When San Franciscans hike up Twin Peaks or stroll through Glen Canyon Park, they could be exposing themselves to an herbicide that some studies have linked to cancer. But thanks to growing concerns about public health and liability, their risks are substantially lower than they were five years ago, when the city used 20 times as much of the chemical.

That chemical is glyphosate, the key ingredient in Monsanto’s top-selling weedkiller, Roundup. Monsanto owner Bayer agreed in June to a settlement of more than $10 billion with plaintiffs in thousands of pending lawsuits over claims Roundup caused cancer.

As legal victories against the company pile up, Bay Area cities have faced a tough choice — keep using a chemical that evidence increasingly shows is dangerous and exposes them to the legal liability it entails or switch to other, often less effective methods. San Francisco has limited its risk through a strategy known as integrated pest management and its move to scale back dramatically on glyphosate since 2015.

An aerial rendering shows the proposed BUILD development at 700 Innes in Bayview-Hunters Point, with the city's proposed park at 900 Innes at bottom right.

Is This the Bayview’s Big Park Moment?

The Bayview has the city’s attention – for better or for worse, depending on whom you ask. If voters approve a $487 million open-space bond measure in November, it will help fund a park at 900 Innes Ave., the first waterfront land the city’s Department of Recreation and Parks has ever owned. Yet, despite efforts to include the local community in the planning and the benefits, many are skeptical.