Autism has become a front-and-center concern for many families as diagnoses reach new highs. According to the CDC, about 1 in 31 children in the U.S. is now diagnosed with autism spectrum disorder (ASD) — a dramatic rise from decades ago.
Stepping into the conversation, U.S. Health Secretary Robert F. Kennedy Jr. has raised alarms by suggesting that environmental “toxins” — including mold, pesticides, food additives, certain medications, and even prenatal ultrasounds — may be fueling what he calls an autism epidemic.
Kennedy, known for his populist style and controversial public health positions, has promised to launch a sweeping research initiative to uncover the cause of autism. “By September, we will know what has caused the autism epidemic,” he told President Donald Trump, claiming it could be eliminated by removing specific exposures.
At the core of Kennedy’s theory is the belief that modern life has introduced harmful environmental elements not present in past generations.
He links the rise in autism to increased use of processed foods, pharmaceuticals, and prenatal technologies — arguing that these “new” exposures must explain the surge.
Kennedy has long promoted discredited claims that childhood vaccines are linked to autism — a stance scientists have repeatedly debunked.
Now, he’s broadening his focus beyond vaccines, but experts warn that his new list of suspects lacks compelling evidence as well.
Scientific community pushes back
Health experts say Kennedy’s toxin theory oversimplifies a complex condition.
Autism, they emphasize, is a neurodevelopmental difference shaped by a mix of genetic and environmental influences — not a poisoning caused by a single trigger.
“There’s no credible evidence that everyday exposures like mold or ultrasound scans are causing autism,” said Dr. Peter Marks, a former FDA official. “Giving people false hope is something you should never do.”
Researchers worry Kennedy’s push could reignite interest in theories that have already been rigorously tested and rejected. “There’s deep concern we are going backward,” said Kristyn Roth of the Autism Society of America.
The numbers behind the narrative
Kennedy and others often cite CDC data showing autism rates have climbed from 1 in 150 children in the early 2000s to about 1 in 31 today.
In some communities, nearly 1 in 20 boys are diagnosed — leading many to describe the trend as an “autism epidemic.”
But scientists caution that the rise reflects better awareness and broader diagnostic criteria more than an actual explosion in cases.
In the past, autism diagnoses were limited to more severe developmental challenges.
Today, the term “autism spectrum disorder” includes a wider range of presentations, including milder and previously overlooked cases.
“Expanded criteria and increased screening have played a huge role,” said Dr. Karen Pierce, co-director of the UC San Diego Autism Center.
Pediatricians now routinely screen toddlers, and social stigma around autism has decreased, prompting more families to seek evaluations.
Experts also point to demographic shifts. Diagnoses have increased across all races and socioeconomic groups — especially in communities that were historically underdiagnosed. Today, more girls and children of color are being recognized as autistic, suggesting a “catching up” effect rather than a sudden new threat.
Still, is there a real rise?
While improved diagnosis explains much of the trend, some researchers acknowledge there may also be a small real increase in autism rates.
Factors like older parental age, changes in reproductive patterns, and certain prenatal conditions may contribute incrementally.
“There does seem to be an underlying increase,” said Dr. Céline Gounder, a public health expert. “But it’s not caused by any one thing.”
Importantly, no environmental factor studied so far — including those Kennedy lists — has been proven to cause autism.
Most children exposed to things like food additives or prenatal ultrasounds do not develop ASD, and many autistic children have no known exposure to potential risk factors.
What science actually says about causes
Decades of research have shown that autism is largely genetic. Studies of twins and families consistently find that inherited traits account for 80–90% of autism risk.
Dozens of genes have been linked to the condition, underscoring its roots in brain development beginning before birth.
Environmental factors may influence autism risk, but their impact is far smaller and often difficult to isolate.
The NIH lists several possibilities — from air pollution during pregnancy to low birth weight or maternal health conditions — but none are definitive.
Most importantly, these risk factors are not new, and they don’t explain the rapid rise in diagnoses.
Vaccines, perhaps the most heavily scrutinized environmental factor, have been conclusively ruled out.
Multiple large-scale studies involving millions of children show no difference in autism rates between vaccinated and unvaccinated groups.
Similarly, Kennedy’s newer concerns — such as prenatal ultrasounds — have also been examined.
These scans have been standard in obstetric care for decades without corresponding spikes in autism in heavily scanned populations.
Gender gaps raise more questions
Autism is diagnosed about 3.8 times more often in boys than girls.
This consistent pattern raises questions about any theory blaming external toxins: Why would modern exposures disproportionately affect boys?
Researchers believe biological differences may make boys more vulnerable, or that girls are underdiagnosed due to subtler presentations of autism.
Either way, this gender gap complicates Kennedy’s one-size-fits-all theory.
Stigma, support, and the danger of oversimplification
Beyond scientific critique, advocates are concerned that Kennedy’s framing of autism as a tragedy caused by “toxins” may reinforce harmful stigma.
Autism is not a disease to be cured, they argue, but a form of neurodiversity that society should support and accommodate.
“Claims that autism is caused by environmental exposures, parenting styles, or vaccines not only lack scientific evidence but are incredibly irresponsible,” said Christopher Banks of the Autism Society of America.
The Autistic Self-Advocacy Network echoed these concerns, calling Kennedy’s promise to find a definitive cause by September “absurd.”
Such statements, they warn, could mislead families and divert resources from real needs like early intervention, inclusive education, and adult services.
The bottom line
Kennedy’s toxin theory resonates with parents searching for answers — especially amid rising autism diagnoses.
But scientists caution that his claims are not backed by evidence and risk reviving discredited theories.
Autism is a complex, multifactorial condition.
Its rise is real, but it’s rooted in broader recognition, expanded definitions, and shifting demographics — not simply in what we eat, breathe, or scan.
As the public conversation around autism grows, experts urge that it be grounded in science, compassion, and a commitment to understanding — not fear.
