U.S. Health and Human Services Secretary Robert F. Kennedy Jr. announced Thursday that the department has launched a “massive testing and research effort” involving hundreds of scientists worldwide, aiming to determine the cause of what he described as the “autism epidemic” by September. However, experts have raised concerns about the integrity of the effort, given Kennedy’s long-standing and widely discredited claims linking vaccines to autism.

“We’ve launched a massive testing and research effort that’s going to involve hundreds of scientists from around the world,” Kennedy told President Donald Trump during a Cabinet meeting. “By September, we will know what has caused the autism epidemic, and we’ll be able to eliminate those exposures.”

Trump responded that such findings would lead to the “biggest news conference,” suggesting, “There’s got to be something artificial out there that’s doing this.”

Rates of autism have steadily increased in the U.S., with the CDC reporting 1 in 36 children identified with autism spectrum disorder in 2020—up from 1 in 150 in 2000. Kennedy claimed on Thursday that the number may now be as high as 1 in 31.

Medical researchers attribute the rise to a combination of broader diagnostic criteria, increased awareness, improved screening, and earlier detection. While the exact causes remain unclear, contributing factors may include genetics, advanced parental age, and environmental exposures like air pollution or pesticides.

What experts agree does not cause autism: vaccines.

“No link has been found between autism and vaccines, including those containing thimerosal, a mercury-based compound,” according to the National Institute of Environmental Health Sciences.

Still, Trump appeared to entertain the idea that Kennedy’s initiative could uncover a direct cause.

“If you can come up with that answer, where you stop taking something, you stop eating something, or maybe it’s a shot,” he said. “But something’s causing it.”

Kennedy has a long history of anti-vaccine advocacy. Despite assuring Sen. Bill Cassidy, who chairs the Senate Health, Education, Labor and Pensions Committee, that he would not dismantle the federal vaccine safety system, Kennedy’s actions in office have raised alarm.

Last month, he directed the CDC to reexamine links between vaccines and autism—even though its own data has long shown no connection. Under his leadership, Dr. Peter Marks, the top vaccine regulator at the FDA, was pushed out. In his resignation letter, Marks wrote that Kennedy “wishes subservient confirmation of his misinformation and lies.”

The department has also hired David Geier, a controversial figure who co-authored a now-retracted study with his father falsely claiming a link between vaccines and autism, as a senior data analyst.

Kennedy has further come under fire for minimizing a deadly measles outbreak in West Texas that has killed two unvaccinated children. Asked on Fox News about one of the deaths, he responded, “She had a lot of complications that could have killed her,” despite state health officials reporting no pre-existing conditions in either case.

Though Kennedy recently offered his strongest public endorsement of the measles-mumps-rubella (MMR) vaccine—telling CBS News, “We encourage people to get the measles vaccine”—he has also praised alternative treatments, such as budesonide and clarithromycin, which are not approved therapies for measles.

“These are not treatments for measles,” said Dr. Adam Ratner, a pediatric infectious disease expert in New York City. “The thing that stops a measles outbreak is vaccination, which is also the thing that prevents the measles outbreak from happening in the first place.”

At Thursday’s Cabinet meeting, Kennedy also claimed that measles cases had “plateaued,” despite data showing continued weekly increases of 19% to 36% in Texas and new outbreaks emerging in Indiana and Ohio. He urged the media to focus more on what he called the “chronic disease epidemic,” citing rising childhood diabetes and autism rates.