Use and safety of Roundup questioned in Michigan and Midwest
Not since DDT was introduced to U.S. agriculture to kill insects after World War Two has a farm chemical been as important to American crop production, and come under more scientific, political, and legal scrutiny as the weedkiller Roundup, and its active ingredient, glyphosate.
The collaborative’s five newsrooms — Bridge Michigan, Circle of Blue, Great Lakes Now, Michigan Public and The Narwhal — are funded by the Charles Stewart Mott Foundation.
With the election of President Donald Trump, the conflict over glyphosate’s risks and benefits entered a new realm of confrontation that has the potential to alter its stature as the favored chemical tool in agriculture, the largest user of fresh water in the blue economy of Michigan and the Great Lakes.
Lee Zeldin, the administrator of the Environmental Protection Agency, is supporting new regulation that would stabilize glyphosate’s continued use by immunizing it from any claims of injury. The rule is consistent with legislation under review in Congress and introduced in 10 states.
But Robert F. Kennedy Jr., the Secretary of the Department of Health and Human Services, also is the country’s most prominent glyphosate opponent, calling it a “poison.” Kennedy has focused on limiting exposure to glyphosate as a feature of his Make America Healthy Again campaign to combat chronic disease. “There are many, many diseases linked to glyphosate exposure,” Kennedy told Joe Rogan, an influential podcaster, in 2023.
Said to be safe by manufacturer
Bayer, the German chemical maker, which controls 40% of the glyphosate market, asserts that glyphosate is safe. The EPA reached the same conclusion so long as the chemical is applied according to the label instructions, which call for wearing long-sleeved shirts, long pants, and washing hands and exposed skin after application. Jessica Christiansen, the chief spokesperson for Bayer’s crop science division, did not respond to repeated requests for an interview.
Because it’s effective in killing weeds at reasonable cost, and because they don’t have to make multiple weed-killing passes in their fields, thus saving fuel expenses, farmers favor glyphosate. With $2.8 billion in annual sales, and roughly 280 million pounds applied annually on U.S. crop fields, most of it on corn and soybeans in Michigan and other Midwest farm states, glyphosate is the best-selling farm chemical ever in American agriculture.
“Glyphosate is important to producers that grow soybeans, corn, sugar beets — most of our field crops,” said Christy Sprague, professor of Crop and Soil Sciences at Michigan State University. “Glyphosate is the one herbicide that is definitely used the most in Michigan. If you talk to any grower that is using herbicides to help manage weeds, they are including glyphosate in some form of their rotation.”
But as its popularity increased since it was introduced in 1974, so did concerns about its presence in the environment and effects on health. The U.S. Geological Survey found traces of the chemical in 94% of the streams it tested in the Great Lakes and Midwest states, and across the country. The Centers for Disease Control and Prevention found that 81% of all Americans are exposed to glyphosate in fruits, fruit juices, vegetables, and cereals, as well as from breathing airborne particles. Separate research by the CDC found 87% of 650 children tested, and 80% of 1,600 adults tested had detectable levels of glyphosate in their urine.
A study by researchers at the University of Michigan found that the presence of glyphosate in pregnant women was linked to an increased risk for premature birth.
Glyphosate also has negative consequences for growing crops. Michigan State University is one of a select group of agricultural universities that has documented the spread of weeds that developed resistance to glyphosate and are damaging yields in 37 of the state’s 83 counties.
The finding pushed glyphosate to the center of ferocious disagreement in Europe and the United States about its safety.
Austria, Belgium, France, and the Netherlands enacted bans on household use of glyphosate. Germany and Portugal banned it in public spaces.
Following the 2015 IARC carcinogenic classification Americans began to file lawsuits to recover financial damages for cancers they asserted were caused by glyphosate. Bayer set aside $16 billion to settle claims and since 2018 has paid over $14 billion in judgments to 115,000 Americans who asserted they weren’t warned about the chemical’s hazards. In the newest verdict, a Georgia jury awarded nearly $2.1 billion in damages in March to a plaintiff who claimed Roundup caused his cancer and he wasn’t sufficiently warned.
Kennedy’s appointment to Trump’s cabinet as the health secretary raised more alarms at Bayer, which fears the U.S. might follow the trend in Europe and severely regulate glyphosate. Kennedy served on the legal team that won the first jury verdict in 2018 that awarded $290 million to a California groundskeeper who asserted that exposure to Roundup was the source of his non-Hodgkin’s lymphoma.
The day after Kennedy was sworn in, President Trump activated Kennedy’s initiative on limiting exposure to glyphosate with an executive order to “aggressively combat the critical health challenges facing our citizens.” In his first address to the agency’s staff in February, Kennedy said "nothing is going to be off limits" in the department's work, including pesticides like glyphosate.
The scientific, legal, and political turmoil is weighing on Bayer’s top executives. Bill Anderson, the company’s chief executive, told the Wall Street Journal in March that Bayer is closing in on a decision to halt sales to farmers. “We’re pretty much reaching the end of the road,” Anderson said. “We’re talking months, not years.”
The consequence of that decision would roil agriculture in Michigan and other states at the center of the country. Glyphosate is applied as a weedkiller to 90% of the country’s row crops. It’s as essential to U.S. harvests as a saddle is to riding a horse. Limiting its use, or banning glyphosate, would raise costs for controlling weeds, the company asserts. And it would compel farmers to use other, more hazardous weedkillers, like paraquat, that has been found to cause damage when it touches the lining of the mouth, stomach, or intestines and may also damage the kidneys, liver, and esophagus.
“There’s not one herbicide that can replace glyphosate,” said Christy Sprague of Michigan State University. “There are, though, a number of herbicides applied in mixtures or sequentially that could act as replacements. But those could, potentially, have health or environmental issues, also.”
“If Bayer backs out of the market many other companies will gladly pick up their market share,” added Charles Benbrook, an agricultural economist who’s served as an expert witness for plaintiffs in several glyphosate trials. “This is a ploy by Bayer to trigger paranoia among farmers that their litigation is going to take their Roundup away.”
Health authorities, families of people injured by the chemical, and legislators who’ve studied the risks say it’s well past the moment when the chemical’s hazards should prompt more intensive restrictions on its use. Here’s why. In testimony in class action lawsuits brought against Bayer, researchers have described how the formula for Roundup includes a sister chemical that enables glyphosate to penetrate through leaves, be transported by the vascular system to the roots, and kill the plant.
The same chemical penetrates human skin enabling glyphosate to reach the bloodstream and bone marrow, where white blood cells form. Research on the behavior of glyphosate in the marrow has found it is capable of causing genetic mutations in developing white blood cells. With regular exposure to glyphosate, from spraying it on farm fields or applying it to kill weeds on lawns and gardens, enough mutations can occur to lead to lymphoma, a cancer that results from white blood cells growing out of control.
“This is one of the big reasons that dermal exposure is a much more dangerous route of exposure than dietary exposure,” said Benbrook. He added that EPA needs to add more stringent safety guidelines to glyphosate’s label that specifically warn of its cancer-causing potential.
Campaign to protect market share
In an expensive effort to protect itself from more billion-dollar verdicts, and to maintain market share, Bayer launched a multi-front counter campaign last year. It convinced attorneys general in 11 Republican-led states to submit a petition asking the EPA to initiate a rulemaking process that would further affirm the EPA’s authority on pesticide labeling. In other words, applying a pesticide that complies with the directions and restrictions on an EPA-approved label means that adequate warnings and requirements have been provided. Litigation would no longer be based on a “failure to warn” claim, which lies at the center of the class action lawsuits.
Bayer has asked the Supreme Court to revisit a seminal decision in a case filed by Texas peanut farmers in the 2000s that upheld the farmers’ “failure to warn” claim in the wake of damage to their crops from a Dow AgroSciences herbicide.
In other actions, Bayer helped Republican members of Congress write legislation, the Agricultural Labeling Uniformity Act. If passed, it would establish EPA registration and label requirements as the safety standard for pesticides. The company also sponsored bills in 10 states calling for the same result.
The record of success is mixed. In April, North Dakota became the first state to enact such a bill into law. The Georgia Legislature approved the legislation in March, and it awaits review by Governor Brian Kemp.
In Iowa, though, where more glyphosate is applied than anywhere in the U.S., and which has developed the nation’s second-highest incidence of cancer, opponents dubbed Bayer’s legislation the “cancer gag act.” The legislation failed in 2024, and was killed again in April by the Iowa House of Representatives.
Dr. Megan L. Srinivas, a physician and Democratic representative from northwest Iowa, was one of the opposition leaders.
“They chose Iowa because if they could get it through Iowa, they could probably get it through everywhere,” said Srinivas in an interview. “The arguments that they made were ‘there's no correlation to cancer.’ They kind of laughed about it and joked about it, ‘there's no science to back any type of health issues with glyphosate.’ And I really thought, based on that conversation, that they had the perception that this was going to go through very easily.”
Chemical opens new farm era
Though DDT was invented to kill bugs and glyphosate developed to clear weeds, both chemicals share comparable levels of importance in American agriculture.
In the years following World War Two, DDT introduced chemical pest-control into agriculture. Glyphosate, developed in 1974 and sold as Roundup by the St. Louis-based Monsanto Company, launched the era of biotechnology in agriculture.
Paired with another scientific breakthrough, glyphosate soared to relevance in the early 1990s. That was when Monsanto scientists discovered a bacteria that showed no ill effects from exposure to glyphosate. The researchers identified the bacterial gene that provided the protection and inserted it into the corn genome.
In 1994 Monsanto introduced genetically modified Roundup-resistant corn to the American market and discovered keen interest among farmers. The chemical was priced right, was easy to apply, and worked so effectively to kill weeds. Soon after, genetically modified varieties of Roundup-resistant soybeans, cotton, alfalfa, canola, and sugar beets also were introduced. The convergence of chemistry and biotechnology in crop production was so valuable that Bayer purchased Monsanto in 2018 for $63 billion.
But every technological advance as significant as breeding crops' resistance to farm chemicals is accompanied by the competition between benefits and risks. Glyphosate’s path to the market was marked by trouble from the very start. In seeking to meet the requirements of registering the chemical with the EPA, Monsanto had to subject glyphosate to long-term rat and mouse toxicity studies to determine its potential effects on people.
It conducted those studies at Industrial Bio-Test Laboratories (IBT), a product-safety testing firm based outside Chicago. Monsanto even dispatched Paul L. Wright, one of its top scientists, to work at IBT to oversee the rodent studies on glyphosate and several more chemicals IBT was conducting for Monsanto.
In 1981, Wright and three top IBT executives were indicted on federal charges of committing one of the worst scientific frauds in U.S. history. Government investigators discovered that IBT faked its rat and mouse studies. Wright and two other IBT executives were found guilty in 1983 after a long trial and sentenced to short prison terms and fines.
In the years since, no other farm chemical has been swept up in a longer, more expensive, and more visible confrontation over risks and benefits as glyphosate.
Farmers are paying attention. Dennis Kellogg, who is 76 years old and farms soybeans with his son on 220 acres in Ithaca, Michigan, is well aware of the risks of farm chemicals, including glyphosate. A cancer survivor — likely due, he says, to exposure to years of applying “chemicals and handling fertilizer and that type of thing” — Kellogg began using Roundup four years ago to increase yields.
He doesn’t blame Roundup for any of his health problems but is careful in how he applies it to his fields. Kellogg does not allow his son to spray Roundup. “I don’t want him exposed to any of that chemical,” he said in an interview.
Kellogg’s concern also is founded in the experience of his wider family. His brother-in-law died of non-Hodgkin’s lymphoma late last year. He was 64 years old and spent 30 years of his work life spraying Roundup as a technician in Michigan for TruGreen, the lawn care company.
Before he died, the TruGreen technician became a plaintiff in one of the class-action lawsuits, asserting his disease was the result of exposure to glyphosate and was awarded a small settlement. In an interview, his widow confirmed those details but asked that neither she nor her husband be identified in this article.
Dennis Kellogg is not nearly as reticent. “Oh goodness,” said Kellogg of his brother-in-law. “It got into his bones and stuff. He died from exposure to Roundup. I’m sure about that.”
