- The U.S. Forest Service is spraying record amounts of glyphosate on fire-damaged public lands across California, with 266,000 pounds applied in 2023 alone — five times the amount sprayed 20 years ago.
- The agency uses the herbicide to kill native vegetation that competes with commercially valuable conifer species replanted after wildfires.
- A key study used to justify the spraying — a 2000 paper concluding glyphosate poses no health risk — was retracted in November 2025 after being exposed as ghostwritten by Monsanto employees.
- The Forest Service's 2011 risk assessment, which remains in use, cites the retracted paper 27 times and relies heavily on industry-funded research.
- Health experts warn the spraying threatens nearby communities, watersheds, wildlife and especially children, whose developing systems are uniquely vulnerable to glyphosate exposure.
Why the Forest Service is spraying record herbicide
Northeast California's Lassen National Forest once teemed with wildflowers, bees and towering sugar pines. Today, vast stretches of the burn zone left by the 2021 Dixie Fire resemble a barren, sun-bleached desert—devoid of birds, animals or insects.
The devastation is not solely the work of flames. According to an investigation by Mother Jones published in May 2026, the U.S. Forest Service and private timber companies are spraying record amounts of glyphosate — the active ingredient in Monsanto's Roundup — on fire-damaged public lands. California sprayed 266,000 pounds of glyphosate on forests in 2023, nearly five times the amount used two decades ago, making forest spraying the fastest-growing market for the controversial herbicide in the state.
The Forest Service plans to spray up to 75,000 acres destroyed by the 2021 Caldor Fire near Lake Tahoe, including campgrounds, trailheads and areas close to homes. Another 10,000 acres in the Lassen burn zone are scheduled for treatment starting spring 2026, with workers using backpack sprayers to apply up to 8 pounds of glyphosate per acre.
The ghostwritten science behind the spraying
At the heart of this controversy lies a question of scientific integrity. The Forest Service's 2011 risk assessment, which broadly depicts glyphosate as posing no significant threat, relies heavily on a 2000 study by Dr. Gary Williams and colleagues published in Regulatory Toxicology and Pharmacology. That paper concluded glyphosate posed no health risk to humans.
In November 2025, the journal retracted the study after learning that Monsanto employees had ghostwritten the paper and that the named authors had relied entirely on company data while disregarding other evidence. Internal Monsanto emails, obtained through lawsuits, reveal a systematic campaign to manipulate the scientific record — a strategy reminiscent of Big Tobacco's decades-long deception.
Monsanto scientist William Heydens wrote in a 1999 email that the company sought researchers who would "get up and shout Glyphosate is non-toxic." When one expert the company hired concluded that glyphosate could cause chromosome damage linked to cancer, Monsanto executives dismissed his findings and never reported them to the EPA. They instead recruited scientists willing to declare Roundup safe.
The Forest Service's risk assessment cites Williams' retracted paper 27 times — more than any other peer-reviewed article. Five of the seven most-cited journal articles in the report were either orchestrated by Monsanto or written by authors with financial ties to the company.
Children face unique risks from widespread exposure
California pediatrician Dr. Michelle Perro, an expert on glyphosate's effects on children's health, said the spraying poses particular dangers to young people. "Children are not simply mini adults," Perro said. "Their developing neurological, endocrine, immune and detoxification systems are uniquely vulnerable to environmental exposures like glyphosate."
Research supports these concerns. A 2023 study led by University of California Berkeley professor Brenda Eskenazi followed 480 mothers and their children for more than 18 years. The study found that young adults exposed to glyphosate in the womb or during early childhood showed a 14% increase in liver inflammation and a 55% increase in metabolic syndrome — conditions that can lead to liver cancer, diabetes and cardiovascular disease.
A 2024 study at Arizona State University found that mice fed glyphosate at levels the EPA considers safe in human food developed brain inflammation that persisted for months after the chemical was removed from their diets. The exposure also resulted in premature death and Alzheimer's-like brain damage.
The Centers for Disease Control and Prevention found glyphosate residues in more than 80% of urine samples collected from U.S. adults and children. A 2020 U.S. Geological Survey study detected the chemical in 74% of American streams tested.
Lax oversight and worker safety concerns
Despite California's relatively strict chemical regulations, oversight of forest spraying remains minimal. When state regulators were asked for all site inspection reports for forest spraying from 2020 through 2022, they returned only 11 records despite more than 8,000 reported sprayings covering a quarter-million acres.
One inspection report from El Dorado County documented contract workers handling Roundup without gloves and lacking protective equipment or safety training. The inspector photographed a worker's hand stained purple with the herbicide.
Bayer, which acquired Monsanto in 2018, has paid more than $12 billion to resolve lawsuits over Roundup-related cancer claims. The company still faces more than 60,000 lawsuits. In 2018, a jury awarded $289 million to Bay Area groundskeeper Dewayne Johnson, concluding that occupational exposure to Roundup caused his non-Hodgkin lymphoma. A California appeals court later reduced the award but affirmed that jurors were entitled to declare Roundup dangerous based on evidence that Monsanto had behaved unethically to sway regulators.
From tobacco tactics to forest management
The parallels to Big Tobacco are striking. Monsanto's campaign to shape the scientific conversation around glyphosate — ghostwriting studies, recruiting compliant experts and suppressing unfavorable research — mirrors strategies used for decades by cigarette manufacturers to obscure the link between smoking and cancer.
A retired EPA veterinarian, Marion Copley, wrote to colleague Jess Rowland in 2013, imploring him to follow the science on glyphosate, which she "strongly believed" triggered tumors. "For once in your life, listen to me and don't play your political conniving games with the science to favor the registrants," Copley wrote before dying of breast cancer nine months later. Rowland later faced scrutiny for his relationship with Monsanto; internal emails showed him assuring company employees he could help manage regulatory outcomes.
The Forest Service's reliance on glyphosate marks a departure from traditional forest management. Quebec, one of North America's largest timber-producing regions, banned glyphosate in 2001 and switched to manual and mechanical methods to control vegetation. A 2010 government study found minimal effects on timber yields. California, meanwhile, continues to expand spraying. Gov. Gavin Newsom signed an emergency executive order in 2024 allowing state agencies to bypass normal safety procedures when applying the herbicide.
A path forward or more of the same?
The Trump administration has further complicated the situation. A February executive order deemed glyphosate critical to national security, invoking the Defense Production Act to boost domestic production and extend some legal immunity to manufacturers. The solicitor general asked the Supreme Court to hear a case that could shield Bayer from further Roundup lawsuits, with oral arguments scheduled for April 27.
The Forest Service acknowledges it can achieve similar timber yields without chemicals by using workers and machines, but at triple the cost — a "major factor" in the decision to spray, according to a 2024 agency report. That report cites a 40-year-old study claiming injuries are more likely when vegetation is culled by hand, but it does not address health risks for crews spraying chemicals.
For residents like Joe Van Meter, owner of the Mill Creek Resort near Lassen, the issue is personal. His family's water source comes from Mill Creek, which originates in nearby Lassen Volcanic National Park and flows through areas targeted for spraying. Recent studies have found that glyphosate-based herbicides cause "deleterious effects" on fish development and reproduction. Mill Creek remains one of California's last undammed spawning grounds for spring-run Chinook salmon.
"We need work to be done, and so I want to see that work done," Van Meter said. "But I want it done without the use of toxic chemicals."
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