One of the country’s most widely used weed-killing chemicals is now persona non grata in the city of Napa.

A policy announced last week closes off any future uses of glyphosate products on city property, completing a phase-out that Napa began three years ago. The move away from the herbicide widely sold under the Roundup brand for 45 years comes amid increasing controversy over the chemical’s safety record – intensified by a court verdict that implicated glyphosate in a California man’s battle with cancer.

The latest change, which City Manager Steve Potter announced March 19 to the City Council, formalizes what has been the practice of avoiding glyphosate into a formal policy applying to all Napa staff. It also extends the ban on Roundup use to contractors working on any properties owned or used by the city, and requires employees to immediately file a report to a superior if a glyphosate product has been or is being applied at a city site.

Potter said the policy, which did not require a council vote, stems from recent emails and inquiries by Napa residents over the past month about the state of city rules governing glyphosate use.

Napa began pulling back from the use of glyphosate in 2016 when the city parks department stopped using the chemical for weed control, followed by a similar move by the utilities department a year later. In the place of Roundup, workers have moved toward a combination of less toxic substances, mulching and mechanical removal to control the spread of invasive plants.

No glyphosate products have been used by Napa workers in at least a year and a half, and no contractors are known to have used the weed killer in recent months on city property, according to Potter. “All we were doing was formalizing the discontinuation of its use in a very public way,” he said Monday.

“I want to thank you for being so responsive; I’m surprised by how quickly this moved from an email I wrote,” Amy Martenson, a former Napa Valley College trustee and one of the letter writers to the city, told Potter and the City Council. Martenson is co-coordinator of GMO-Free Napa County, which advocates for reducing the use of synthetic pesticides and herbicides.

Potter’s announcement took place on the same day a jury in San Francisco federal court ruled that glyphosate-based herbicide was a substantial factor in the non-Hodgkin’s lymphoma afflicting Edwin Hardeman, 70.

Hardeman, who filed suit against Roundup’s manufacturer Monsanto, is the second plaintiff to go to trial out of thousands nationwide who allege the weed killer causes cancer. His trial will enter a second phase to determine whether Monsanto is liable and, if so, for how much money.

The connection between glyphosate and cancer has become the subject of intense debate. Monsanto, which brought Roundup to market in 1974, has strenuously denied any connection and cites hundreds of studies identifying the chemical as safe, but California has since 2017 listed glyphosate as a probable carcinogen under Proposition 65, the state law that requires warning labels for products deemed to cause cancer.

The dispute has extended to the national and international levels as well. Glyphosate has not been listed as a cancer risk by the Environmental Protection Agency, but the World Health Organization listed the weed killer as “probably carcinogenic” in a 2015 report.

Records indicate that glyphosate products are used on about 250 different crops within California and is sold it more than 160 countries, with sales boosted by its effectiveness on a wide range of weeds as well as “Roundup Ready” soybean and corn varieties that can endure spraying even as surrounding weeds die.

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Information from The Associated Press was used in this report.


Public Safety Reporter

Howard Yune covers the city of Napa and the town of Yountville. He has been a reporter and photographer for the Register since 2011, and previously wrote for the Marysville Appeal-Democrat, Anaheim Bulletin and Coos Bay (Oregon) World.