A new peer-reviewed study has found no evidence that exposure during pregnancy to traces of pesticides commonly found on fruits and vegetables is linked to autism-related traits in children, a finding that challenges one of the environmental factors Health and Human Services Secretary Robert F. Kennedy Jr. has suggested could be contributing to rising autism rates.
The research, published on August 24 in JAMA Pediatrics, examined pesticide metabolites in urine samples collected from pregnant women and later evaluated their children for autism-related social difficulties. Researchers found no association between the pesticide exposures measured and traits commonly associated with autism spectrum disorder. The findings come as Kennedy has repeatedly cited pesticides among the environmental exposures he believes warrant investigation as possible contributors to autism.
The study adds to an ongoing debate about the causes of autism and how to explain an increase in diagnoses across the United States. While Kennedy has argued that environmental toxins must be playing a major role, many researchers and medical organizations point to a complex mixture of genetic and environmental influences and say there is no evidence that a single factor is responsible.
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Newsweek reached out to Kennedy for comment via email.
What Did Autism Prenatal Study Find?
The study tracked more than 3,000 mothers who were part of the National Institutes of Health’s (NIH) Environmental Influences on Child Health Outcomes (ECHO) Program. Researchers from New York University (NYU) analyzed urine samples collected during pregnancy to assess exposure to organophosphate pesticides, chemicals commonly used in agriculture that can leave trace residues on produce.
According to the study and accompanying NYU Langone announcement, researchers found that nearly all participating pregnant women had detectable levels of pesticide metabolites, reflecting the widespread presence of these substances in food and the environment. Despite the prevalence of exposure, investigators found no evidence that higher levels were associated with increased autism-related social difficulties in children.
The mothers were enrolled in the study between January 1997 and December 2019. The mothers gave one urine sample during pregnancy and then, years later, filled out a 65-question survey about their child’s social behavior. Among the questions asked were how well their child reads other people’s feelings and if they struggle with eye contact.
Researchers concluded that prenatal exposure to the organophosphate pesticide metabolites measured in the study did not predict autism-related traits. The findings were notable because they were based on biological measurements of exposure collected during pregnancy rather than estimates based on residential proximity to farms or self-reported dietary habits.
However, the authors said they couldn’t rule out that the risk of autism could be greater among people with exposure to high levels of pesticides or among people with genetic susceptibilities.
The findings arrive amid heightened national attention on autism research following Kennedy’s calls for studies into environmental causes of the condition.
What RFK Jr. Has Said About Pesticides and Autism
Kennedy has repeatedly argued that environmental exposures are responsible for what he describes as an autism epidemic.
Following the release of a Centers for Disease Control and Prevention (CDC) report on autism prevalence in April 2025, Kennedy said autism was caused by an environmental exposure rather than genetics alone.
“We know it’s an environmental exposure. It has to be,” he said. “Genes do not cause epidemics. They can provide a vulnerability, but you need an environmental toxin.”
As part of the research effort he announced, Kennedy said federal officials would investigate a range of potential environmental factors, including pesticides, food additives, mold, medicines, obesity, ultrasound exposure and contaminants in water.
He has not claimed that pesticides have been definitively proven to cause autism. Rather, he has argued that they deserve closer scrutiny as a possible explanation for the increase in autism diagnoses.
Those assertions have drawn criticism from autism researchers and public health experts, who say existing evidence does not support the idea that a single environmental toxin explains autism prevalence.
What Is Autism?
Autism, formally known as autism spectrum disorder (ASD), is a neurodevelopmental condition that affects how people interact, communicate, learn and experience the world around them.
The condition exists on a spectrum, meaning symptoms and support needs can vary widely from person to person. Some autistic people require substantial support in daily life, while others live independently and may have fewer challenges.
According to the CDC, characteristics of autism can include differences in social communication, difficulty interpreting social cues, repetitive behaviors, highly focused interests and sensitivities to sensory experiences such as sound or light.
Scientists have identified hundreds of genes associated with autism, and researchers generally view the condition as arising from a complex combination of genetic and environmental influences rather than a single cause.
Many autism advocates also emphasize that autism is a neurological difference rather than a disease that needs to be cured. The language used to describe autism remains a source of debate within the scientific and autistic communities.
Is Autism Rising in U.S.?
Autism diagnoses have increased dramatically over the past several decades, though researchers disagree about how much of the rise reflects a true increase in prevalence versus changes in diagnosis and awareness.
The CDC reported in 2025 that about 1 in 31 U.S. children aged 8 had been identified with autism spectrum disorder in 2022. That compared with about 1 in 36 children in the agency’s previous surveillance report and roughly 1 in 150 children when national monitoring began in 2000.
Kennedy has pointed to those figures as evidence of an environmental cause driving a surge in autism rates. But many researchers argue that expanded diagnostic criteria, better screening, increased awareness among clinicians and parents, and improved access to services have played a major role in the rise in diagnoses.
Experts interviewed by PolitiFact and PBS said no single factor has been shown to account for the increase. Instead, they suggest a combination of changing diagnostic practices and a growing understanding of the condition explains much of the trend.
That scientific disagreement has helped fuel debate over how government agencies should prioritize autism research funding and what questions future studies should seek to answer.
What Signs of Autism Did Study Use?
The new study did not diagnose children with autism spectrum disorder. Instead, researchers measured autism-related traits, particularly social difficulties that are commonly associated with autism.
Investigators relied on standardized behavioral assessments completed when children reached school age. The evaluations focused on social communication challenges and behaviors frequently examined in autism research. Researchers then compared the results with pesticide exposure levels measured during pregnancy.
The use of autism-related traits rather than formal autism diagnoses allowed researchers to examine whether prenatal pesticide exposure was associated with characteristics commonly observed among autistic people across a broader population sample.
The findings do not rule out the possibility that other environmental factors may influence neurodevelopment. However, they add to a growing body of evidence suggesting that the low-level pesticide exposures many people encounter through ordinary diets are unlikely to explain rising autism prevalence.
For policymakers and researchers, the study is likely to become part of an increasingly contentious debate over autism’s origins. For Kennedy, who has highlighted pesticides as one potential environmental culprit, the results represent a significant challenge to one of the theories receiving renewed national attention.
Contact Newsweek editors on this story: Jenni Fink and Dave Siminoff.