Pesticides once appeared to be a clear target for Robert F. Kennedy Jr.’s desire to “make America healthy again.” Before becoming the health secretary, he described Monsanto, the maker of the glyphosate-based herbicide Roundup, as “enemy of every admirable American value,” and vowed to “ban the worst agricultural chemicals already banned in other countries.” Since he came to power, many of Kennedy’s fans have waited eagerly for him to do just that.
Kennedy has yet to satisfy them: In the latest MAHA action plan on children’s health, released last week, pesticides appear only briefly on a laundry list of vague ideas. The plan says that the government should fund research on how farmers could use less of them, and that the government “will work to ensure that the public has awareness and confidence” in the EPA’s existing pesticide-review process, which it called “robust.”
Unlike Kennedy’s concerns about vaccines, his concerns about pesticides have echoed those found in a body of legitimate research. Studies have found associations between exposure to some herbicides and pesticides and cancer, hormone disruption, and other acute and chronic health conditions. These include neurodevelopmental impacts in children, such as autism—which Kennedy has also promised to tackle.
Right now his department’s promised report on what has caused rates of autism to rise over recent decades is expected to highlight Tylenol use, whether during pregnancy or, as my colleague Tom Bartlett reported, based on Kennedy’s correspondence with a fringe researcher, in early childhood. Researchers generally point to a change in diagnostic criteria as the primary reason rates have spiked so dramatically. They also consider autism a complex condition that does not appear to have a single cause: Studies suggest that genetics play a bigger role than environmental factors in determining a person’s risk, though both seem likely to contribute and may work in concert. A serious effort from the government to understand its causes would require investment in long-term, large-cohort, and detailed studies that might cast light on the contribution of many environmental factors, including pesticides.
Several studies have found neurological impacts associated with pesticides. UC Davis’s MIND Institute put out a study in 2014 that found autism risk was much higher among children whose mothers had lived near agricultural-pesticide areas while pregnant. A 2017 paper found that zip codes that conducted aerial spraying for mosquitoes—a pesticide—had comparatively higher rates of autism than zip codes that didn’t. Others have linked pesticides to a range of behavioral and cognitive impairment in children.
Rebecca Schmidt, a molecular epidemiologist and professor at UC Davis, has been researching potential risk factors for autism as part of the school’s long-term MARBLES study of mothers and children. Schmidt and her colleagues study families with at least one child already diagnosed with the condition—to see what environmental and biological factors may raise the risk of subsequent children being diagnosed. (Younger siblings of a child with autism have on average a 20 percent chance of also having it.) Her own research, she told me, has not seen as dramatic of results for pesticides as the 2014 paper—which she also worked on—reported, though other labs have found associations of their own between prenatal pesticide exposure and autism.
These studies, like most studies that assess environmental exposures, typically cannot determine causality between agricultural-pesticide exposure and autism risk. Investigating links between pesticides and health outcomes is challenging; researchers can look at geographic proximity to sprayed fields, but drilling down to find out how much pesticide actually ended up in a person’s body requires herculean diagnostic efforts, such as frequent urine sampling. And the conclusions drawn from these studies can only point to associations between certain exposures and the likelihood of developing the condition: Showing direct causality would involve willingly exposing pregnant mothers and infants to pesticides and seeing what happens, which scientists cannot do, for obvious reasons. But based on what she knows now, Schmidt told me, “pesticides are probably not a good exposure for any pregnant person, or even children,” since their brains are still developing.
In investigating autism causes, Kennedy could also consider another environmental factor: air pollution. Breathing air pollution does have robust evidence linking it to neurodevelopmental effects in children, including autism. The Trump administration’s policy changes since January have predominantly tipped the country toward more air pollution, not less, while its climate-policy rollbacks will contribute even further to the burden of air pollution from wildfires. Meanwhile, some evidence also suggests a link between flame-retardant exposure and behavioral-developmental problems in children. Other studies have found possible links between pre- and postnatal exposure to PFAS, or “forever chemicals,” and autism.
All of this means that following the science would give Kennedy many places to look. “We’ve been working on this for over a decade,” Schmidt told me. “Every time we do a study, it raises new questions. And so it’s a complex picture that takes time to tease apart.” Designing and completing strong studies of any of these factors is challenging and costly. If the federal government did want to put its resources toward finding the causes of autism, Kennedy would do well to increase funding for large, national studies that follow people for years.
The latest MAHA plan does say that the National Institutes of Health, along with other agencies, will develop a way to evaluate “cumulative exposure,” or the impact of the cocktail of chemicals Americans are regularly interacting with—including pesticides. It does not say how that research will be funded or which of the tens of thousands of in-use chemicals the agencies would focus on.
Since taking office, Kennedy has mostly avoided even rhetorically linking specific environmental exposures to health concerns. An earlier MAHA report had more to say on pesticides, but The New York Times and Politico reported that Republican lawmakers as well as the farm lobby expressed concern about its potential impact on farmers. At a Senate hearing, Kennedy said that there are “a million farmers who rely on glyphosate” and told lawmakers that “we are not going to do anything to jeopardize that business model.” At a Heritage Foundation event last month, Kennedy’s senior adviser, Calley Means, said on a panel that corn and soybean farmers are not the “enemy,” but rather that the “deep state” is. (Corn and soy are two of the most heavily sprayed crops.) In response to a request for comment, HHS pointed me to last week’s MAHA plan, as well as the EPA’s work to evaluate environmental risks while phasing out animal testing.
This shift has raised the ire of some of Kennedy’s most ardent fans. Zen Honeycutt, the founder of the advocacy group Moms Across America who has been a major Kennedy supporter, said shortly after the MAHA plan was unveiled last week that her vote for the Republican Party is not guaranteed: “We will be actively campaigning to get people into office coming in the midterms that will protect our children, and we are not beholden to political parties.” In a statement later that day, she said that eliminating specific mentions of glyphosate and atrazine, another widely used pesticide that appeared in the first report and has concerning health implications, is “a tactic to appease the pesticide companies.”
Some of Kennedy’s defenders rightly point out that he is not in charge of the EPA, which regulates pesticides, or the U.S. Department of Agriculture, which oversees farming policies. Even if he cannot regulate pesticides himself, he is in charge of the National Institutes of Health, “and the NIH can study the causes of the effects of these chemicals on Americans. Those studies can drive the marketplace and policy change,” Vani Hari, a food activist, MAHA influencer, and vocal supporter of Kennedy, told me. (In particular, she wants to see the United States, as some other countries have, eliminate the practice of spraying glyphosate on crop fields right before harvest, which farmers do to dry out the crops.) Kennedy understands the threat these chemicals pose, she told me: “When there is an opportunity to add influence, he will. He’s not afraid to speak up.”
I asked whether she would be disappointed if the forthcoming autism report doesn’t mention pesticides and instead focuses on Tylenol and folate deficiencies. She told me she doubted that the autism report would overlook pesticides. “I don’t see that even happening,” she said. Yet in his few months in office, Kennedy has had many chances to let science guide him and has let them pass—on the health benefits of seed oils, the safety of abortion pills, children’s mental-health screening, and, most notably, vaccine policy. This may be one more.