In remarks laced with scientific inaccuracies, Robert F. Kennedy Jr., the secretary of the Department of Health and Human Services, said on Wednesday that autism was preventable while directly contradicting researchers within his own agency on a primary driver behind rising rates of the condition in young children.
Mr. Kennedy made his comments at a news conference, responding to a new report from the Centers for Disease Control and Prevention showing that rates of autism had increased to one in 31 among 8-year-olds, continuing a long-running trend.
Blaming environmental risk factors for the uptick, he accused the media and the public of succumbing to a “myth of epidemic denial” when it came to autism. He also called research into the genetic factors that scientists say play a vital role in whether a child will develop autism “a dead end.”
“Genes don’t cause epidemics,” he said. “You need an environmental toxin.”
Autism rates among children have increased nearly fivefold since 2000, when the C.D.C. first began collecting data on the condition’s incidence in children. The C.D.C.’s new report attributed some of the increase in autism’s prevalence to more screening for the condition. And researchers have pointed to several other factors, including greater awareness of what autism looks like, more access to services, more parents having children later in life and broader definitions of the disorder.
Mr. Kennedy vowed that under his leadership, the health department would focus on looking into certain substances, like mold and food additives, and parental obesity to try to reverse rising rates of autism in children.
“These are kids who, many of them, were fully functional and regressed because of some environmental exposure into autism when they’re 2 years old,” he said.
Scientists have not ruled out the possibility that both genes and environmental factors could influence whether a child develops autism. Still, there is no evidence to suggest that autism can be avoided, and researchers immediately criticized the suggestion.
Dr. Eric Fombonne, who is a longtime autism researcher and professor emeritus at Oregon Health & Science University, called Mr. Kennedy’s claim “ridiculous.”
“Autism is not an infectious disease. So there aren’t preventive measures that we can take,” said Dr. Joshua Anbar, an assistant teaching professor at Arizona State University who helped collect data for the C.D.C. report.
Though Mr. Kennedy did not specifically mention vaccines in his remarks on Wednesday, he has previously sought to tie childhood vaccinations to rising rates of autism.
Dozens of studies have failed to establish a link between autism and vaccines. Nevertheless, the health department recently hired a discredited vaccine skeptic to examine the theory.
When asked by a reporter whether differences in the way autism is diagnosed could explain the rise in cases, Mr. Kennedy argued such changes could account for no more than a fraction the increase.
Researchers said there is no one reason autism rates have risen, but that increased screening was likely a large factor.
“The more you look for it, the more you find,” said Dr. Maureen Durkin, a professor of population health sciences and pediatrics at the University of Wisconsin-Madison who has long studied autism. Dr. Durkin is one of the authors of the C.D.C. report.
Mr. Kennedy repeatedly dismissed the idea that screenings had driven the uptick as a “canard” and chastised “epidemic deniers” for focusing on genetics instead of environmental factors.
He argued that genes could not do any more than predispose someone to be more susceptible to environmental factors, likening it to the fact that not all smokers die of lung cancer.
Experts said there is legitimate research to be done examining potential environmental factors, but recoiled at Mr. Kennedy’s apparent all-or-nothing approach, which seemed to discount entirely the merits of continuing to study the genetic underpinnings of the condition.
Scientists have known since the 1970s that genetics contribute to the development of the neurodevelopmental disorder. Studies of twins from that time showed that identical twins were more likely than fraternal twins, who do not have the same genetic makeup, to develop the disorder.
Studies since have identified hundreds of genetic abnormalities that are associated with autism.
“We know there is a clear genetic contribution. That is not in question,” said Catherine Lord, a psychologist and autism researcher at the University of California, Los Angeles. “The question is, could it interact with environment? Could it be that someone who has a genetic risk for autism is then exposed to something that then results in autism?”
Mr. Kennedy also reiterated plans to commission studies to identify environmental toxins to explain rising rates of the condition. He said he would have “some of the answers” by September, and then invite the research community to participate. “We’re going to task them with certain outcomes,” he said.
Mr. Kennedy said the studies would focus particularly on toxins that were introduced into the environment around 1989, identifying that as the year the autism “epidemic” began — a claim disputed by experts. The first study of autism was published in 1943, and the condition was added to the Diagnostic and Statistical Manual of Mental Disorders, the primary classification system used by psychiatrists, in 1980.
Dr. David Mandell, a psychiatry professor at the University of Pennsylvania, said that researchers would be better off looking into the genetic components of autism and funding efforts to develop new services to support people with the condition.
“We are being set up to look up in the wrong place, to put our money in the wrong place,” Dr. Mandell said.
