On the heels of a new report showing that rates of autism diagnoses have again increased, Health and Human Services Secretary Robert F. Kennedy Jr. said he was determined to find the “environmental exposures” behind the rise and directed the National Institute of Health to launch new studies into “everything” — from mold to obesity — that could potentially be a factor.
Kennedy, who prioritizes autism as one of the chronic illnesses he’s determined to tackle in his aim to “Make America Healthy Again,” ardently pushed back against the explanation that a broadening definition of autism spectrum disorder is a meaningful contributor to more autism diagnoses.
Secretary of Health and Human Services Robert F. Kennedy Jr. speaks during a news conference at the Department of Health and Human Services, April 16, 2025, in Washington, D.C.
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Kennedy said he wanted to “move away” from the idea that “the autism prevalence increases — the relentless increases — are simply artifacts of better diagnoses, better recognition or changing diagnostic criteria.”
“This epidemic denial has become a feature in the mainstream media, and it’s based on an industry canard. And obviously there are people who don’t want us to look at environmental exposures,” Kennedy said, speaking at a press conference at the department headquarters on Wednesday in Washington, D.C.
The report Kennedy mentioned — published Tuesday by the Centers for Disease Control and Prevention — estimated that autism prevalence has increased to 1 in 31 children, which Kennedy called “shocking.”
In 2020, the same report found a prevalence of 1 in 36, and over two decades ago in 2000, the rate was 1 in 150.
Experts in the field agree that the rates of diagnoses are increasing and that environmental factors could be at play — but also say most of the increase can be attributed to the expanding definition of autism, which broadened dramatically in recent decades to include subtler features of the illness, including new descriptors as recently as 2013.
“It’s a fair question” to ask why autism prevalence has increased, Dr. Catherine Lord, a psychologist and autism researcher at UCLA’s David Geffen School of Medicine, told ABC News, but she said that it’s also important to acknowledge how much has changed.
“There’s been a huge shift in terms of awareness of autism, particularly awareness of autism without severe intellectual disability, that really changed even since I entered this field,” said Lord.
Studies also suggest that autism risk is heavily rooted in genetics, by as much as 80%.
Dr. Walter Zahorodny, a clinical psychologist and professor who studies autism at Rutgers University, joined Kennedy at Tuesday’s press conference to emphasize that there has been a “true increase” in cases, something he said he has seen throughout his career in New Jersey — though he acknowledged, unlike Kennedy, a wider variety of possibilities, from environmental exposures to other “risk factors.”
“It is a true increase. There is better awareness of autism, but better awareness of autism cannot be driving disability like autism to increase by 300% in 20 years,” Zahorodny said, referring to studies from New Jersey and the CDC report.
Zahorodny said finding the cause was crucial and lamented a lack of progress to “address this question seriously” over his career.
“I would urge everyone to consider the likelihood that autism, whether we call it an epidemic, tsunami or a surge of autism, is a real thing that we don’t understand, and it must be triggered or caused by environmental or risk factors,” he said.
Kennedy on Tuesday acknowledged that the increase in autism diagnoses could be in part caused by increased awareness, but said that still left a large portion of the jump in diagnoses unaccounted for.
He called it “indefensible” to accept awareness as the main reason, describing high stakes of ruined families and “individual tragedy.”
“Autism destroys families, and more importantly, it destroys our greatest resource, which is our children. These are children who should not be suffering like this,” Kennedy said. “These are kids who will never pay taxes, they’ll never hold a job, they’ll never play baseball, they’ll never write a poem, they’ll never go out on a date. Many of them will never use a toilet unassisted.”
“We have to recognize we are doing this to our children, and we need to put an end to it,” he added.
Not every case is as severe as Kennedy described, however; many people diagnosed with autism live highly functional adult lives. The recent CDC report found fewer than 40% of children diagnosed with autism spectrum disorder were classified as having an intellectual disability, meaning an IQ of less than 70.
Dr. Barry Prizant, an adjunct professor in the department of communicative disorders at the University of Rhode Island and director of the private practice Childhood Communication Services, told ABC News that Kennedy’s comments misrepresent what autism is like for families.
“I am not dismissing the challenges. There are considerable challenges, and a lot of those are barriers to services,” he said. “We’ve been doing a parent retreat weekend for 27 years, where we spend a weekend with 60 parents and family members, and we’re not meeting with family members and parents who say, ‘Autism is just a tragedy and it’s hell in our lives.’ They talk about the positives and the negatives, the joys as well as the challenges.”
Autism Speaks also released a statement on Wednesday, calling Kennedy comments “extremely disappointing and damaging.”
“Autism is not a preventable condition,” the nonprofit autism organization said. “The suggestion that it is—especially when linked to environmental toxins without scientific evidence—contributes to decades-old misinformation and distracts from the real needs of autistic people and their families.”
Kennedy said the NIH, led by Dr. Jay Bhattacharya, a former professor at Stanford University, will soon announce a series of new studies aimed at identifying precisely which environmental toxins are to blame. Kennedy cited mold, food, pesticides, medicines, ultrasounds, and the age and health of parents as possible culprits.
Kennedy qualified that the study would provide “some of the answers” by September, which is a variation — welcomed by experts — from his claim to President Donald Trump last week that “by September, we will know what has caused the autism epidemic.”
However, he also claimed on Tuesday: “We know it’s an environmental exposure.”
Asked by ABC News if he would commit to following the science revealed by the studies, regardless of his current expectations on what’s causing the rise in diagnosis, the secretary said yes.
“We’re going to follow the science no matter what it says,” he said.
Medical experts have been studying the potential causes of autism for decades. Research to date suggests that autism is driven by genetics, and the risk may increase when paired with certain outside factors, such as having children at an older age or exposure to pollutants.
“It’s not simple,” Lord said. “If you look at high-quality publications, the findings are small and, in terms of causes other than the genetics, have been quite hard to replicate. Not meaning they’re wrong, but just that we haven’t quite figured out what they should be.”
HHS or NIH have not provided details about how the new studies will be conducted within the given timeframe, but Kennedy pledged transparency, saying the studies would be conducted in the traditional way of funding to academic institutions through the NIH.
