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Data reporting by Melissa Lewis
In remote Northeast California, about 10 miles outside the lumber mill town of Chester and a half-hour’s drive from the old hunting cabin I bought and fixed up about a decade ago, I steer my old Toyota Tacoma down a bumpy dirt road to where the Lassen National Forest gives way to private timberland. Lilly rides shotgun.
We’d come to this exact spot seven years ago. Lilly, my sharp-eyed border collie, had jumped out of the truck and chased a rabbit through a meadow of knee-high grass, returning covered in mud and burrs. The landscape was straight out of an L.L.Bean catalog: a flower-dotted meadow buzzing with life. Douglas firs, incense cedars, and some of the tallest sugar pines on the planet sheltered protected species ranging from gray wolves to Pacific fishers and northern goshawks. The Sierra Nevada red fox, one of California’s rarest mammals, was known to live nearby, amid the vast patchwork of private and public lands. The Lassen area is where I come to reset, forage for wild mushrooms, and let stress evaporate.
But today, I’m looking out over a barren, sun-bleached expanse that stretches across the former meadow and up the sides of denuded mountains as far as the eye can see. No birds. No animals. No insects. No big trees. Just some waist-high piles of volcanic rock, a nod to the still-active Lassen Peak nearby. It is eerily quiet—desolate. The Dixie Fire roared through here in July 2021, burning nearly 1 million acres. The Park Fire three years later took out another 430,000 acres nearby. But the fires aren’t directly responsible for what I’m seeing today. People did this.
Just a few minutes down the road, nature has crept back to life. There, I saw vibrant green mountain whitethorn bushes, rabbitbrush, and purple-tinged bull thistles, with energetic bees bopping from flower to flower. The towering trees were gone, but new saplings abounded—cedars, pines, firs, and more—scattered randomly amid the greenery, already a foot or two high. No such verdant revival is visible on the private timberland before me. No bees, no flowers—it’s a virtual dead zone where the only life consists of row upon row of manually planted, tightly packed conifer saplings, all less than a foot tall.
This is because, unbeknownst to most people, logging companies and the US Forest Service have been spraying massive amounts of herbicide in clear-cut and fire-ravaged forests of California—and throughout the nation. And not just any herbicide, but glyphosate, a potent and problematic weed killer best known by the brand name Roundup.
This once-idyllic landscape, spanning tens of thousands of acres, is among California’s most heavily sprayed forest areas. The Pacific Crest Trail—a hiking route immortalized in the Hollywood movie Wild, starring Reese Witherspoon—runs straight through it. Yet thanks to all the chemicals, it remains a moonscape even now, nearly five years after the Dixie Fire.
I keep Lilly in the truck.
Burn zones treated with glyphosate lack signs of life even years after the fires. The Pacific Crest Trail passes through this area—California’s most heavily sprayed forestland in 2023.Scott Anger
Reporter Nate Halverson examines land sprayed with glyphosate in the wake of the 2021 Dixie Fire.Scott Anger
My first hint of all this was a single word in a letter the Forest Service sent to me and my neighbors about a year and a half ago. Lassen, it said, was to be part of an ambitious new wildfire recovery project. This was welcome, as the fires had burned perilously close to our properties. Workers would remove selected trees, cull undergrowth, and set prescribed fires, as Native Americans have done for millennia to keep forests healthy and reduce the risk of megafires. The agency also would plant new trees where few had survived.
Then I came to the word “herbicides.” The Forest Service would, starting in spring 2026, spray glyphosate on some 10,000 acres of public land in Lassen to wipe out leafy plants and shrubs that might compete with replanted conifers, whose needles allow them to tolerate the chemical.
Introduced in 1974 by agri-giant Monsanto, glyphosate is among the world’s most controversial herbicides, one the World Health Organization’s cancer agency calls a probable carcinogen. In the late 1990s, widespread spraying on US crops genetically engineered to withstand it helped propel the organics movement and led scientists and activists to decry the chemical’s potential to wreak environmental havoc, from decimating monarch butterfly populations to killing wild frogs.
Bayer, the multinational conglomerate that acquired Monsanto in 2018, has agreed to pay more than $12 billion in legal settlements to thousands of people who say Roundup gave them cancer or other ailments. (Bayer says its herbicide is safe when used as directed.) But the company, which has hired lobbyists with deep ties to the Trump administration, may have notched a win in February, when President Donald Trump issued an executive order deeming glyphosate critical to national security. He even invoked the Defense Production Act to bolster domestic production of the herbicide and extend some immunity from lawsuits to its manufacturers.
The Forest Service and private loggers say they use glyphosate because it helps commercially attractive conifers like pine and Douglas fir rebound faster after fires and timber harvests. It does so by killing deciduous trees, native shrubs, flowering plants, and anything else that might compete for water, nutrients, and sunlight. In short, a key rationale for spraying a disputed chemical in natural settings boils down to executives and regulators treating forests, including our national forests, as tree farms.
To learn more about how widely glyphosate was being used and the risks of using it in places where people camp, forage, hike, hunt, and swim, I began by requesting all California spraying reports going back to 1990. My colleague Melissa Lewis and I analyzed more than 5 million records, and what we found was eye opening: Forest spraying, which practically nobody knows about, is happening at record levels. The amount applied annually in state forests—266,000 pounds of pure glyphosate in 2023, the latest year for which data was available—is nearly five times what it was two decades ago. And though far more glyphosate is sprayed on state croplands overall, forest uses have become the herbicide’s fastest-growing market in California.
My Lassen neighbors had a mixture of reactions to the Forest Service letter. Some of them are reflexively averse to environmental concerns. They remember back before the timber wars of the 1990s, when logging boomed and so did good jobs. Classrooms were packed. Families fished, hunted, and called these forests home. Their prosperity was upended by a “tree-hugger” movement to save what remained of California’s old-growth forests. Logging communities were hit hard, and locals paid an economic and emotional price they haven’t forgotten.
Others, upset about the proposed spraying, wrote to the agency to register their opposition. They knew of the health concerns—studies suggesting glyphosate might contribute to ailments ranging from non-Hodgkin lymphoma to brain inflammation and metabolic and liver problems in children. There’s a growing body of evidence, too, suggesting it disrupts the gut microbiome, with implications for chronic disease. (Bayer disputes these findings and says glyphosate safety is “supported by one of the most extensive bodies of research.”)
How, I wondered, given the myriad health and environmental concerns, had regulators come to approve so much forest use of glyphosate—especially at a time when bad press around the chemical had left many a farmer and landscaper searching for alternatives? At least part of the answer lies within the thousands of pages of additional public records, court filings, and internal Monsanto emails I obtained.
The collected documents detail a secret campaign the company hatched in the late 1990s—not unlike the ones used by Big Tobacco decades earlier—to counter public health concerns and convince government agencies to keep approving its multibillion-dollar product. They show how Monsanto orchestrated, financed, and even ghostwrote studies that were published in peer-reviewed scientific journals under the names of supposedly independent researchers—papers that state and federal agencies have relied upon to justify copious spraying of Roundup.
As my reporting proceeded, the questions kept piling up: Is glyphosate as safe for humans as Bayer insists? Does it really help forests bounce back after fires or, conversely, might it leave them more susceptible? And finally, what would come of the Trump administration setting two key parts of its coalition—Big Agriculture, which embraces glyphosate, and the Make America Healthy Again crowd, which loathes it—on a collision course?
This hillside, burned in the 2024 Park Fire, has not yet been treated with glyphosate. Scott Anger
Reporter Nate Halverson stands in the scar of the 2024 Park Fire, where baby trees and other plants are reemerging from the ashes, and where the Forest Service plans to spray glyphosate this spring. Scott Anger
Back in the burn zone, a sudden movement catches my eye; not a rabbit this time but a dust devil forming. It swirls and dances over the sunbaked terrain, taking on the color of the rust-colored dirt. The vortex grows ever larger, now towering hundreds of feet in the air, where an overhead wind, like an unseen paintbrush, streaks the reddish dirt off into the distance, a miles-long trail of impressionistic art.
This can’t be good. That topsoil was drenched with chemicals not so long ago. Now it’s airborne and presumably traveling well beyond the intended spraying boundaries. Joe Van Meter, owner of the Mill Creek Resort about 15 miles away, mentions the dust devils when I visit him. He’s seen them, too, on his drive to Chester.
Van Meter is a charming and earthy fortysomething who in 2017 bought the nearly century-old, 12-acre resort with his wife, Jillian. They are raising their three young daughters here, having revitalized the old cabins, RV sites, and campground, adding retro trailers and glamping tents to attract the hip Bay Area crowd. “As you see, we’ve got a little slice of heaven,” he tells me.
The resort, as its name suggests, sits alongside Mill Creek, which originates in nearby Lassen Volcanic National Park and meanders through the area. The fast-flowing mountain creek has long been hallowed ground for Native Americans and anglers because it remains undammed and is a spawning ground for some of the state’s last remaining spring-run Chinook salmon. Recent studies have found that glyphosate-based herbicides caused “deleterious effects” on fish development and reproduction, which is one reason Van Meter has helped lead local pushback to the Forest Service’s plan. Having perused the science—and lawsuits—he also fears that spraying Roundup on local hillsides, whose feeder streams empty into the creek, could taint his community’s primary water source.
“It seems like it’s poison that they’re putting into the woods,” Van Meter says.
“This is our backyard. This is where my children play.”
He gets the need for fire mitigation. The 2024 Park Fire burned right up to the edge of his property and sent him fleeing for his life on highways lapped by flames. “We came to a couple points where we had to stop because of how intense it was ahead of us,” he recalls. But the family got out and the resort was spared. The earlier Dixie Fire had also come close, forcing him and Jillian to shut down at the peak of the busy summer season. As such, he’s on board with the thinning and replanting and supports logging in the area, but Van Meter and others oppose the use of Roundup and related herbicides. “We need work to be done, and so I want to see that work done,” he says. “But I want it done without the use of toxic chemicals.”
Roundup has been on the market for half a century, but sales exploded in the late 1990s after Monsanto introduced “Roundup-ready” GMO soybeans and corn, crops genetically modified to withstand a direct hit with glyphosate. This allowed farmers to kill everything else in their fields, increasing crop yields and giving struggling growers hope that they might eke out more money. Monsanto cashed in doubly by selling them both Roundup and the seeds that could survive it.
But after a series of studies in the late 1990s indicated glyphosate might be harmful to people, Monsanto executives and scientists concocted a plan to convince regulators otherwise. Internal emails obtained through discovery in various lawsuits against the company show how Monsanto personnel sought out researchers who would “get up and shout Glyphosate is non-toxic,” as William Heydens, one of the company’s scientists, told colleagues in a May 1999 email. Their testimonials, he wrote, could “be referenced and used to counter-balance the negative stuff.”
In the emails, Heydens, who helped spearhead the strategy, and whom we tried to contact without success, emphasized that his team would work with “outside scientific experts who are influential at driving science, regulators, public opinion, etc.” They turned first to a British scientist, James Parry, a globally recognized expert on genetic mutations. But Parry’s internal report to Monsanto concluded that glyphosate potentially caused clastogenicity—chromosome damage—which can lead to cancer. He recommended more tests.
Monsanto executives were not thrilled. Heydens informed his crew that the company had no intention of doing “the studies Parry suggests”—the goal, rather, was to identify scientists willing to declare Roundup safe. “Let’s step back and look at what we are really trying to achieve here. We want to find/develop someone who is comfortable with the genetox profile”—an assessment of cancer risk—“of glyphosate/Roundup and who can be influential with regulators,” he wrote. “My read is that Parry is not currently such a person.”
The border between unsprayed parcels and those where glyphosate has been applied is hard to miss.Scott Anger
Reporter Nate Halverson visits a site burned by the 2024 Park Fire where dead trees are being cleared and harvested for sale.Scott Anger
The team turned instead to Dr. Gary Williams, a physician who taught at the New York Medical College. Williams and two co-authors then published an April 2000 review article in the peer-reviewed journal Regulatory Toxicology and Pharmacology. Unlike the Parry report, which included independent research in its analysis, the Williams paper relied entirely on Monsanto’s internal lab tests to evaluate whether glyphosate causes cancer. Its conclusions were unequivocal: “There is no potential for Roundup herbicide to pose a health risk to humans.” (Williams could not be reached for comment.)
In another email, this one from a trove of trial records dubbed the Monsanto Papers, Heydens reminded his team they’d ghostwritten the Williams paper, a claim he would later deny under oath. “Apparently I didn’t have good recollection, because that’s not what happened,” he said in a 2017 deposition. But the emails make clear that ghostwriting was widely discussed at Monsanto. Michael Koch, an executive who oversaw teams responsible for Roundup and glyphosate’s safety and regulatory approval, emailed subordinates at one point to ask them to orchestrate a study with a “manuscript to be initiated by MON ghostwriters” and published by one of their go-to scientists—Williams and four others were listed as options. Heydens, one of the recipients, noted in a separate message that “we would be keeping the cost down by us doing the writing and [the outside scientists] would just edit and sign their names, so to speak.” Their imprimatur would make the articles more credible to regulators and the public, he added.
Monsanto would orchestrate several influential studies over the years. In 2016, Williams was the lead author on another paper secretly overseen by the company and published at a crucial moment. WHO’s International Agency for Research on Cancer had made headlines the year before by concluding that glyphosate probably causes cancer. Monsanto responded with a PR onslaught that included a ghostwritten Forbes op-ed under the byline of former FDA official Henry Miller, a Stanford Hoover Institution fellow and regular contributor to the magazine. “The reality is that glyphosate is not a human health risk,” it concluded. (When Forbes editors learned Monsanto had ghostwritten the piece, they cut ties with Miller, who did not respond to requests for comment.)
Heydens and other insiders, meanwhile, were busy preparing a series of five new papers involving Williams and 15 named co-authors. The package ran in the September 2016 issue of Critical Reviews in Toxicology, with a title suggesting it was written by “four independent expert panels.” Critical Reviews, like most academic journals, requires authors to disclose any ethical conflicts in a declaration of interest section, in which Williams et al. wrote: “Neither any Monsanto company employees nor any attorneys reviewed any of the Expert Panel’s manuscripts prior to submission to the journal.”
That was a lie.
The declaration also said the authors “were not directly contacted by the Monsanto Company,” which wasn’t true, either. Monsanto employees had exchanged emails with at least some of them, provided comments and edits on drafts, and in some cases agreed to pay authors tens of thousands of dollars. Heydens himself contributed to the 2016 package: “Here is my 1st shot at starting the Manuscript for the Panel report,” he wrote in an email to colleagues more than a year before it was published. Entire paragraphs from his draft ran verbatim, or nearly so, in the published version, such as: “A molecule with these characteristics would be expected to exhibit, if any, only a low order of toxicity. The results from toxicity studies and regulatory risk assessments have been consistent with that expectation.” Emails and court records show that at least some of the authors were aware of Monsanto’s involvement in editing the package, which, like Williams’ earlier article, was cited in the glyphosate safety assessments of regulators worldwide. “Plaintiff lawyers have cherry-picked isolated emails out of millions of pages of documents,” Bayer said in a statement, and Monsanto’s involvement “did not rise to the level of authorship.”
“We’re not claiming that this paper being retracted proves that glyphosate is scary dangerous. We’re saying it proves that Monsanto poisoned the well of public understanding of science.”
The Forest Service’s 2011 risk assessment, which broadly depicts glyphosate as posing no significant threat to people and the environment, references Williams’ 2000 article 27 times—more than any other peer-reviewed paper, often to refute studies that raised health concerns. In fact, five of the seven most-cited journal articles in the report were either directly orchestrated by Monsanto or written by authors with financial ties to the company.
The only potential human risk acknowledged in the Forest Service’s assessment has to do with people unknowingly ingesting glyphosate after foraging for mushrooms and plants in recently sprayed areas. That’s a problem not just for foragers like me, but for anyone who has ever eaten a chanterelle, morel, or porcini mushroom, none of which can be farmed. Stores and restaurants purchase them from permitted commercial foragers who collect them in wild places, including the Lassen National Forest.
One warm day last August, I drive out to Chester to meet biologist Russell Nickerson, the district ranger in charge of the Lassen spraying. Bespectacled, mustachioed, and clad in the light tan uniform of the Forest Service, he ambles into the district office’s visitor center to greet me. We’re surrounded by taxidermied forest critters, including falcons and owls, a river otter, and a mountain lion set to pounce. Nickerson helped create the October 2024 fire recovery plan, and so, after shaking hands, we head to a little outbuilding to discuss it. The Forest Service has a complex portfolio. On one hand, it manages recreation and conservation in the nation’s woodlands. But as a division of the Department of Agriculture, it also oversees timber production on public land. In the wake of a March 2025 Trump executive order calling for more logging, the agency is more focused than ever on the commercial side of its mission.
That includes reviving areas recently logged or damaged in wildfires so as to regrow the trees as profitably as possible. In Lassen, the agency will deploy workers with portable backpack sprayers to hike through the massive burn zone and apply up to 8 pounds of glyphosate per acre—enough to kill every leafy plant. A first round of spraying is tentatively planned for spring or early summer 2026, followed by another round in the fall. Once new baby conifers are planted, workers will reapply glyphosate one or more times to terminate anything growing too close to them.
Above and below: Timber harvesting operations in the scar of the 2024 Park Fire.Scott Anger
Scott Anger
Nickerson concedes that the Forest Service still relies on its 15-year-old risk assessment—the one that cites Williams 27 times. When I ask him point-blank whether Roundup is safe, he fidgets in his chair and laughs uncomfortably. “It’s probably our Washington office that you would talk to on that,” he says. The chemical is approved, so he uses it.
I show him what I’ve learned about Monsanto’s efforts to sway agencies like his. He shrugs. “Something you’d have to talk about with our national office.”
I then show him a 2020 EPA report that concluded glyphosate harms 93 percent of endangered species and 96 percent of the critical habitat they rely on—creatures including the Sierra Nevada red fox, gray wolf, and spotted owl, all protected in Lassen. Nickerson says he’s never seen the report. Fair enough, but do its findings make him think twice about using Roundup? “Still gotta talk to our national office on that one, sorry,” he says.
As I’m getting ready to leave, he makes a casual comment that sticks with me: It’s his understanding that the agency’s risk assessment says glyphosate is so safe “you could bathe in it.” I looked, and it doesn’t say that exactly. It does say that if you were fully immersed in undiluted glyphosate, there would be no cancer risk. One of the sources it cites for skin contact being safe? Williams et al., 2000. Nickerson later disputes using that language. His point, he says, was that given the quantities of glyphosate used by the Forest Service, it “did not rise to a level of concern.”
In December, four months after we spoke in person, Regulatory Toxicology and Pharmacology announced it was retracting the 2000 Williams article. The journal had “lost confidence in the results and conclusions,” Co-Editor-in-Chief Martin van den Berg wrote, after learning that the paper’s named authors, Williams, Robert Kroes, and Ian Munro, “were not solely responsible for writing its content” and had relied entirely on Monsanto data, disregarding other evidence.
The retraction was prompted by a critical analysis shared with the editors by scientists Naomi Oreskes and Alexander Kaurov. Oreskes is co-author of Merchants of Doubt, a 2010 book showing how corporations deliberately distort science to influence policy. “We’re not claiming that this paper being retracted proves that glyphosate is scary dangerous,” Oreskes tells me. “We’re saying it proves that Monsanto poisoned the well of public understanding of science.”
It also nullifies the Forest Service’s most-cited journal article in support of glyphosate safety. The agency, which had previously declined me an interview with its chief, Tom Schultz, provided a statement noting that the USDA supports the EPA’s “use of gold-standard science to assess pesticide safety.”
Oreskes doesn’t fault the regulators. They “are making a good-faith assumption that because this paper was published in a respectable, peer-reviewed journal that it was a legitimate paper and that its findings were valid,” she says. But “what we’ve shown is that it was not a legitimate paper.” Rather, it was a ploy by Monsanto “to manipulate the scientific conversation and thereby the regulatory conversation, and to persuade people of the safety of a product [when], in fact, there is significant scientific evidence to raise concern.”
“As a person who studies scientific integrity, that profoundly offends me,” Oreskes says. “But also, it’s crucial because it means we can’t trust what they say.”
A 2020 EPA report determined that glyphosate harms a wide range of wild animals and their habitats. This artistic rendition shows a gray fox photographed in California’s Bodie Mountains.Billie Carter-Rankin; Ken Hickman/Forest Service Research Data Archive
The Forest Service intends to keep using Roundup, and far more heavily than in years past, per our analysis of California pesticide reports, which include herbicides. It approved a plan that could spray more glyphosate on those 10,000 Lassen acres than it sprayed in an average year two decades ago across its entire portfolio of 193 million acres. It also plans to spray up to 75,000 acres affected by the 2021 Caldor Fire, including spots near Lake Tahoe’s famed ski resorts—such as the base and parking lot at Sierra-at-Tahoe and in forests close to Kirkwood and Heavenly. The plan includes spraying in campgrounds, around trailheads, and close to homes in Meyers. These applications alone will amount to more spraying in California’s woodlands than happened in all of 2023.
It is difficult to say whether the Golden State is an outlier, because most states, unlike California, don’t have a mandatory and comprehensive reporting system for commercial pesticide and herbicide users. But a 2020 EPA study largely based on private industry data suggests that glyphosate use may be even more prevalent elsewhere: Sixteen Southern states accounted for about 90 percent of the nation’s overall forest spraying in 2016, the authors estimated.
The Forest Service acknowledges it can get similar timber yields by reforesting without chemicals, using workers and machines, but at triple the cost—expense is a “major factor” in the decision to spray, according to a 2024 agency report. The same report cites a 40-year-old study that claims injuries are more likely when vegetation is culled by hand, but it doesn’t address potential health risks for crews hired to spray the chemical.
Oversight of spraying is lax, even here in California. When I asked state regulators for records of all site inspections for forest spraying from 2020 through 2022, they returned only 11 reports, despite more than 8,000 reported sprayings covering a quarter-million acres during those three years. In one report, from El Dorado County, an inspector witnessed contract workers handling Roundup with their gloves off. They’d been hired to spray on Forest Service land but had neither the protective equipment nor the safety training mandated by the state. The inspector snapped a photo in which one of the workers’ hands is bright purple—covered in Roundup.
Skin exposure was central to the first-ever glyphosate cancer lawsuit against Monsanto. In 2018, a jury awarded $289 million to Bay Area groundskeeper Dewayne Johnson, concluding that occupational exposure to Roundup caused his non-Hodgkin lymphoma. The 1st District Court of Appeal reduced the award to $20.5 million but ruled that the jurors were entitled to declare Roundup dangerous based on WHO’s review, expert witnesses, and evidence that Monsanto had behaved unethically to sway regulators and research findings. “Even if the evidence did not require an inference that Monsanto was more concerned about defending and promoting its product than public health, it supported such an inference,” the presiding judge wrote.
Craig Thomas, a fire reduction expert who in 2021 served on a congressional wildfire recovery commission with then–Agriculture Secretary Tom Vilsack, raised similar concerns with the Forest Service, he says, and was told the agency wasn’t aware of anyone harmed by spraying Roundup on the job. “And I’m like, ‘No, they die of non-Hodgkin lymphoma 15 years later,’” Thomas tells me when we meet up not far from my cabin to survey land where the agency plans to spray.
I show him some of what I’ve found. “Oh god, that’s totally corrupt,” he says. “Do we care about human beings or our natural landscapes? Doesn’t sound like it.”
Forest Service mascot Smokey Bear, he declares, has become a glyphosate junkie. “It’s a chemical addiction that’s been fostered inside the agency with the help of Bayer and Monsanto,” he says. “The system operated for thousands of years without it.”
You don’t need herbicides for fire recovery, Thomas says. That’s about cost cutting.
The forests, he says, can be adequately managed using just machines, laborers, and tools such as prescribed burns.
Consider that Quebec, the largest timber-producing region in North America, has eliminated glyphosate and other herbicides in 90 percent of its forests. Back in 1994, the province put in place a “forest protection strategy” designed to balance jobs and profits with healthy forests. Glyphosate, once widely used, was banned in 2001, and logging companies switched to manual and mechanical methods to stifle plant competition with minimal effects on yields, according to a 2010 government study. Now, instead of enriching a German chemical company, the money goes to pay local workers.
Quebec’s experience has gone unheeded by California officials, who aim to expand glyphosate spraying in state-run forests as part of their own fire prevention strategy. Gov. Gavin Newsom even signed an emergency executive order last year allowing the state Department of Forestry and Fire Protection (Cal Fire) and other agencies to bypass normal safety procedures when spraying the herbicide.
The state’s plans rely on Cal Fire’s 2015 glyphosate safety report, which also leaned on Monsanto’s ghostwritten studies. The report’s author, contractor Bill Williams, who is unrelated to the physician Monsanto recruited as the lead author for its papers, has a long history working for the chemical industry. He once, for instance, argued that dioxin, a highly toxic chemical known to cause cancer and other health problems, doesn’t hurt bald eagles. (It does.) At a 2003 chemical industry event, he gave a presentation titled “A Little Pesticide Is Good For You,” arguing that the EPA should loosen regulations around pesticide exposure. (Williams did not respond to my outreach attempts.)
While working on the Cal Fire report, according to his own résumé, Williams was also working for a consulting company, Cardno, that helps firms like Monsanto recruit scientists to conduct and write studies for them. That same year, court records show, a Cardno scientist pitched Monsanto executives, offering to help manage Roundup’s PR problem in the wake of WHO’s carcinogenicity declaration.
California already sprays glyphosate in state parks, such as Jackson Demonstration State Forest, where it issues permits for people to forage for mushrooms and where the Mycological Society of San Francisco hosts an annual gathering. Last year’s attendees were unaware of the spraying, several members told me. And that’s problematic, because many foragers and chefs recommend not rinsing wild mushrooms in order to maintain their flavor. But eating unwashed food recently sprayed with glyphosate is a problem—even the Forest Service’s outdated risk assessment says so.
High on the list of California’s biggest overall glyphosate users is the state Department of Transportation, which sprays along roads and highways to keep flammable grasses and brush in check. Caltrans also sprays in counties, including Los Angeles, that won’t let their own workers use the herbicide. The spraying isn’t just in rural areas. Records show Caltrans has been applying herbicides in downtown Hollywood, right along Santa Monica Boulevard.
The state’s No. 1 forest sprayer in 2023, records show, was Sierra Pacific Industries, a timber company owned by billionaire Trump supporter Archie Aldis “Red” Emmerson. Sierra Pacific is the largest landowner in the state and the second-largest in the country, controlling more acreage than Ted Turner and Bill Gates put together. It was responsible for 70 percent of reported glyphosate spraying in California’s wooded areas that year, including the lands near my cabin. The company did not respond to multiple requests for comment—ditto the timber company Collins, another major user.
The irony of firms and government agencies spraying replanted burn zones is that they may be setting us up for more trouble down the road. Deciduous hardwoods such as oak, aspen, and birch can slow a fire’s progression, studies show, whereas resin-filled conifers are more flammable than other trees. A densely packed commercial conifer forest like the one I saw taking shape near Chester is, according to a growing scientific consensus, a megafire waiting to happen.
An artistic rendition. The US Forest Service is now gearing up for more woodland spraying in California—including in campgrounds, around trailheads, and near ski resorts—than ever before recorded.Billie Carter-Rankin; Randy Pench/Sacramento Bee/Getty
Given everything we’ve learned, it’s worth asking: Just how bad is glyphosate for human health?
The science on cancer is mixed. Even successful lawsuits like Johnson’s found it to be only a weak or modest carcinogen. But that’s not the only worry. Brenda Eskenazi, a professor emeritus at the University of California, Berkeley, has studied glyphosate for decades. For a 2023 article, she followed 480 mothers and their children in California’s Salinas Valley for more than 18 years, testing their urine periodically. She found statistically significant increases in the prevalence of liver inflammation (14 percent) and metabolic syndrome (55 percent)—which can result in liver cancer, diabetes, and cardiovascular disease later in life—among young adults exposed to glyphosate in the womb or during early childhood. “Everyone was focused on cancer, and they weren’t looking elsewhere,” Eskenazi tells me. “There are other health effects that have long-term impacts.”
Given the heated rhetoric around glyphosate, Eskenazi speaks with restraint. “We need more research,” she says. Yet much of her funding has been in limbo since the Trump administration hit the brakes on grants from the National Institutes of Health. Without those funds, her lab may have to shut down and destroy some 400,000 biological samples. But she is unwilling as yet to pass final judgment on the safety of the world’s most widely used herbicide. “There are a lot of little pieces that make us concerned,” she says, but “I’m not one of these people who say we shouldn’t use pesticides at all. I think we should use it discretionarily and carefully. That means when nothing else works.”
Bayer asserts in its statement that “regulators, including the EPA, EU, and others around the world, have repeatedly concluded that glyphosate-based products—which are the most widely used and extensively studied products of their kind—can be used safely according to the product label directions.” The EPA’s glyphosate assessment relied heavily on a 2018 analysis based on the Agricultural Health Study. The researchers asked 57,310 people who had applied for pesticide licenses in North Carolina or Iowa whether they used glyphosate and then followed up with a series of health-related questions. The study, published in the peer-reviewed Journal of the National Cancer Institute, found no statistically significant correlation between glyphosate exposure and cancers such as non-Hodgkin lymphoma. But the paper had its critics. Lianne Sheppard, a professor of biostatistics at the University of Washington who served on the EPA’s scientific advisory panel on glyphosate, published a critique in the same journal arguing that the authors’ approach was likely to underestimate cancer risk. The authors responded, explaining why they believed their results were valid.
And so it goes. “I have friends who are good scientists and think it causes non-Hodgkin lymphoma,” David Eastmond, a professor of toxicology at UC Riverside, tells me. “And I have others who think it doesn’t.”
Eastmond is in the latter camp. About 10 years ago, a joint task force assembled by WHO and the UN’s Food and Agriculture Organization asked him and other scientists to conduct a new review of glyphosate studies in light of the 2015 probable-carcinogen determination. Whereas that determination had relied exclusively on published research, Eastmond and his colleagues were given full access to Monsanto’s internal glyphosate data as well. “This industry dataset was almost entirely negative for cancer and genotoxicity,” he recalls. With this data in the mix, he and his colleagues concluded glyphosate was unlikely to cause cancer. But his work preceded revelations that Monsanto was tampering with the scientific process—the lies and the ghostwriting. “Yeah, that’s totally dishonest,” Eastmond says. “A lot of this is very sleazy.”
Can Monsanto’s data still be trusted? “I think it’s fair to be skeptical,” he says. “When someone is putting pressure to manipulate things, then I become more skeptical, too.”
While the jury may still be out on the extent of Roundup’s harms, we know for certain that it’s in our bodies and environment. A 2020 study by the US Geological Survey found glyphosate in 74 percent of American streams tested. A study published two years later by the Centers for Disease Control and Prevention found glyphosate residues in more than 80 percent of the 2,000-plus urine samples it collected from US adults and children.
Such findings concern Ramon Velazquez, a researcher at Arizona State University whose team’s glyphosate study appeared in the Journal of Neuroinflammation in 2024. They fed glyphosate to mice at levels comparable to what the EPA considers safe in human food. The mice developed brain inflammation that persisted for months after the chemical was removed from their diets. The exposure, the authors wrote, also resulted in premature death of the rodents and Alzheimer’s-like damage to their brains. “I am very cautious about how I eat now,” Velazquez tells me. “I eat an organic diet.”
In 2020, after more than a decade of planning and review, the EPA released an updated glyphosate assessment. It said the herbicide is safe to use and does not cause cancer. Oreskes and Kaurov’s analysis points out that, whereas WHO’s cancer agency looked mainly at peer-reviewed studies, 70 percent of which indicated genotoxic effects, the EPA relied largely on industry-funded studies, 99 percent of which found no cancer links.
The EPA’s approval process was not without scandal. In 2013, Marion Copley, a veterinarian recently retired from the agency, wrote to her former colleague Jess Rowland, who was leading the EPA’s glyphosate cancer assessment. In her letter, now part of the Monsanto Papers, Copley, then dying of breast cancer, implored Rowland 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. For once do the right thing,” she wrote. “I have cancer and I don’t want these serious issues in [the Health Effects Division] to go unaddressed before I go to my grave.” (She died nine months later.)
Above and below: Post-fire growth emerges in as-yet-untreated areas near Mt. Lassen in the scar of the 2021 Dixie Fire. Scott Anger
Scott Anger
Rowland later came under scrutiny for his cozy relationship with Monsanto. While conducting the assessment, he’d spoken regularly with its employees, assuring them he could help, internal emails show. When insiders worried that CDC toxicologists might conduct an independent analysis and conclude that glyphosate was harmful, Rowland said he would try to intervene. One employee quoted him as saying, “If I can kill this I should get a medal.”
Rowland, who could not be reached for comment, left the EPA soon after someone leaked an unauthorized draft of the agency’s preliminary conclusion that glyphosate doesn’t cause cancer, according to court records. Monsanto immediately filed the document in court as evidence to refute claims that Roundup caused cancer.
The EPA inspector general’s office concluded in 2019 that Rowland had done nothing wrong and that there was no evidence the process lacked “scientific rigor.” But the EPA’s official assessment in favor of glyphosate was promptly challenged in court by the Natural Resources Defense Council and Pesticide Action Network North America, which accused the agency of ignoring its own cancer guidelines and glyphosate’s impacts on endangered species. In 2022, the 9th US Circuit Court of Appeals agreed. It overturned the assessment, noting that the “EPA did not adequately consider whether glyphosate causes cancer and shirked its duties under the Endangered Species Act.” The ruling pointed to serious “errors in assessing human-health risk” and noted that most of the studies the EPA examined had “indicated that human exposure to glyphosate is associated with an at least somewhat increased risk of developing non-Hodgkin lymphoma.”
A fresh EPA determination is expected this year. During Trump’s first term, according to one internal email, Monsanto executives were assured they “need not fear any additional regulation from this administration.” Last June, Bayer’s CEO met personally with EPA Administrator Lee Zeldin to discuss glyphosate’s “legal/judicial issues,” per an agency memo obtained by the Center for Biological Diversity. Six months later, Trump’s solicitor general asked the Supreme Court to take a case that would help shield Bayer from further Roundup lawsuits. The court agreed, and oral arguments were set for April 27. (Bayer shares soared 14 percent on the news.) North Dakota and Georgia have passed laws that would give Bayer legal immunity, and more such bills are expected at the state and federal level.
Then came Trump’s executive order saying America must ensure, even boost, production of glyphosate and white phosphorus, an incendiary weapon also manufactured by Bayer. “Lack of access to glyphosate-based herbicides would critically jeopardize agricultural productivity, adding pressure to the domestic food system,” it read.
The MAHA contingent saw the order and went ballistic. “There is a level of anger and frustration like I’ve never witnessed before,” a conservative wellness influencer with millions of Instagram followers told the New York Times. “Where is RFK JR?” asked a commenter. MAHA wants crop chemicals reduced, if not banned entirely, but that could prove a tough sell. Mexico’s leaders ran into heavy resistance in 2024 when they tried to ban glyphosate in their agriculture sector. Farmers were hooked on it and the government ultimately concluded that cutting them off might prove as dangerous to a farm operation as quitting heroin or alcohol cold turkey might to an addict. The ban was rescinded. “It is known to be harmful to health,” then-President Andrés Manuel López Obrador explained, “but there is no substitute.”
And now, as the global food industry grapples with glyphosate addiction, America’s forestry sector is headed down the same path—though, in a small concession to my neighbors, the Forest Service has agreed not to apply glyphosate so close to people’s homes or near certain waterways in the Lassen area, a roughly 2 percent reduction in spraying.
To sum up, the US government botched its safety review of glyphosate, thanks in part to Monsanto’s gaming of the system. Concerned researchers say we need additional data to fully understand the chemical’s harms. But the Trump administration has slashed research funding, and politicians are waiving safety reviews and working to ensure that people who say glyphosate made them sick cannot sue its manufacturer. The Forest Service, meanwhile, plans to spray even more of the herbicide, despite knowing that it hurts nearly all endangered species, that nonchemical options are available, and that its own assessment of human safety hinges on an industry-driven review paper, since retracted.
If all of these revelations are spiking your anxiety levels, you also should probably know that that’s one of the symptoms those Arizona State researchers observed in the mice they’d injected with supposedly safe levels of glyphosate.
