Conservatives Focus on an Unproven Link Between Tylenol and Autism

For more than a decade, scientists have asked whether acetaminophen — the active ingredient in the painkiller Tylenol — could affect fetal brain development, causing problems in children like autism and A.D.H.D. Some studies have suggested that there is a link; others have found none.

Now the latest study, a scientific review by researchers at Harvard’s T.H. Chan School of Public Health and the Icahn School of Medicine at Mount Sinai, has been swept into a larger debate about the causes of autism, spurred in part by the views of Robert F. Kennedy Jr., the Health and Human Services secretary.