On Tuesday, Robert F. Kennedy Jr. held his first press conference as U.S. Secretary of Health and Human Services, announcing plans to investigate the potential environmental links to the higher recorded rates of autism in the country.

Kennedy called the condition an epidemic and claimed it is preventable, saying an “environmental toxin” could be the source of the rising prevalence.

“This is a preventable disease. We know it’s an environmental exposure. It has to be. Genes do not cause epidemics,” the Health Secretary said on April 16, per Reuters.

While Kennedy did not discuss vaccines as a potential cause for the spike in autism, the Health Secretary did note that he would commission a series of studies that will examine factors like “medicines” as a potential source, in addition to mold, air, water, food, and others.

Last month, The Dallas Express reported that the American Academy of Pediatrics (AAP) announced its opposition to the Centers for Disease Control and Prevention’s (CDC) plan to explore the possible connection between vaccines and autism. While the theory remains contentious, Kennedy has previously pledged to support an inquiry into any possible connection.

Although previous studies have not identified links between vaccines and autism, the CDC has previously indicated that it will examine the connection, including assessing the measles, mumps, and rubella vaccine.

Despite the controversy, experts say a combination of both genetic and environmental factors likely causes autism. Some experts claim the rise in autism rates is simply a reflection of expanded screening as well as the growing list of behaviors that now define the neurological and developmental disorder.

Karen Pierce, Co-Director of the Autism Center of Excellence at the University of California, San Diego, says that while autism has a strong genetic component, only one in 10 cases can be explained by an individual gene. Pierce agrees with Kennedy that the expression of the genes “can indeed be influenced by environmental factors.”