President-elect Donald Trump says he’s “open to anything” when it comes to understanding the dramatic rise in autism prevalence, an approach that advocates worry could distract from making real gains for those with the developmental disability.

In an interview with Kristen Welker on NBC’s “Meet the Press” over the weekend, Trump suggested that Robert F. Kennedy Jr., his nominee to lead the U.S. Department of Health and Human Services, would have wide latitude to look into the causes of autism, including investigating the long-discredited connection between autism and vaccines.

“I’m open to anything. I think somebody has to find out,” Trump said in response to questions prompted by Kennedy’s skepticism of vaccines. “If you go back 25 years ago, you had very little autism. Now you have it.”

The estimated prevalence of autism has increased from 1 in 150 U.S. kids in 2000 to 1 in 36 currently, according to the Centers for Disease Control and Prevention. Experts attribute the rise to improved awareness and identification.

Kennedy, however, has spent years blaming the increase in autism on childhood vaccinations. That idea originated from a 1998 study, which has since been retracted. The doctor behind the study had his medical license revoked and subsequent research has found no link between autism and vaccines.

Trump told Welker that he’s “not against vaccines,” but called the rise in autism over the last two decades “pretty scary.”

“I mean, something is going on,” he said. “I don’t know if it’s vaccines. Maybe it’s chlorine in the water, right. People are looking at a lot of different things. I want them to look at everything.”

The comments about autism and vaccines come in contrast to the position of several national autism advocacy groups, including Autism Speaks, the Autism Society of America, the Autistic Self Advocacy Network and the Autism Science Foundation, all of which align with the scientific consensus that vaccines do not cause autism.

“We are concerned,” said Kim Musheno, vice president of public policy at the Autism Society, about Trump’s comments. She pointed to a recent statement that her group issued urging “policymakers and leaders to prioritize accurate information and scientific integrity in all discussions and decisions affecting public health.”

Alison Singer, president of the Autism Science Foundation, said she welcomed interest in studying the causes of autism, but indicated that efforts to revisit any link to vaccines are misguided.

“We can’t let the discredited vaccine hypothesis become a distraction here,” Singer said. “Vaccines are probably the best studied potential cause of autism, and all the studies come back the same; there is no relationship.”

Likewise, Zoe Gross, director of advocacy at the Autistic Self Advocacy Network, warned that studying the long-discredited theory would minimize gains that could be had elsewhere.

“At this point, any time, effort and funding that goes into investigating a supposed link is wasted,” she said. “Worse than that, in order to fund this kind of study, the government would likely have to take funding away from research that could actually help autistic people, such as research investigating best practices in providing services to help autistic people with daily living.”