RFK, Jr., Cites ‘Truly Appalling’ Studies to Tie Autism to Circumcision and Tylenol

RFK, Jr., claims that using Tylenol for circumcision causes autism. Here’s why this statement is wrong

By Allison Parshall

At a cabinet meeting today, U.S. Secretary of Health and Human Services Robert F. Kennedy, Jr. asserted that there is a link between autism and circumcision. “Two studies show that children who are circumcised early have twice the rate of autism. This is very likely because they are given Tylenol,” he said, without citing the studies.

Kennedy was likely referring to a 2013 study of eight countries and a 2015 study from Denmark, both of which claimed to show a link between circumcision and autism rates. Helen Tager-Flusberg, an autism researcher and professor emeritus at Boston University, calls the methods used in these studies “appalling.” Tager-Flusberg leads the Coalition of Autism Scientists, a group that advocates for high-quality autism research.

Neither study shows a causal link between circumcision — or the painkillers that are often prescribed along with the procedure — and higher rates of autism. In the decade since each was published, autism researchers have been highly critical of the studies. And after reviewing both studies, scientists last year found no evidence supporting the claim that circumcision leads to autism or any other adverse psychological effects.

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There is also very little evidence that giving acetaminophen (sold under the brand name Tylenol) to babies or children increases their risk of being diagnosed with autism. There is also very little evidence, as the Secretary of Health and Human Services recently suggested, that acetaminophen taken during pregnancy increases the baby’s risk of developing autism.

For the 2013 study, researchers compared circumcision rates in eight countries, including the United States, with autism rates. They found that countries with higher autism rates tended to have higher circumcision rates. “They’re looking at an association involving a sample of eight countries,” an extremely small number to make such a connection, “and they’re not taking into consideration any other factors about those countries,” says Tager-Flusberg. Factors such as the average age at which one becomes a parent in each country, as well as genetics, are known to affect autism rates. Autism awareness and diagnostic practices also vary from country to country. All of these factors could explain the correlation, but they were not taken into account in the analysis. “I am ashamed that there are colleagues in my field who embarked on such a flimsy study and it was published,” says Tager-Flusberg.

Experts say circumcision rates are not a reliable substitute for acetaminophen use in babies anyway. Researchers in the 2013 study explained that they chose to examine circumcision because acetaminophen is often prescribed after the procedure. The medication is commonly taken for many childhood illnesses and is not always prescribed for circumcision. This means that relying on circumcision to estimate acetaminophen use in newborns is flawed, Tager-Flusberg says.

Scientists who conducted the 2015 study looked at autism rates among 3,347 predominantly Jewish and Muslim boys who were ritually circumcised in hospitals or medical clinics. This study showed a higher likelihood of being diagnosed with autism among this group than among those who had not been circumcised. “This study is riddled with flaws, which others have written about,” psychologist David S. Mandell said in a statement sent to Scientific American on behalf of the Coalition of Autism Scientists. The sample was small, limiting the power of its findings, and did not account for many Muslim circumcisions that are not performed by doctors, likely skewing the results. The association between circumcision and autism was only significant for children aged 0 to 4, and not for those aged 5 to 9, suggesting that there may be another explanation for the results.

These types of observational studies are inherently limited: even if they show a link between two variables, they cannot explain the cause. Relying on weak evidence like this to make claims about the causes of autism is “terribly alarming,” Tager-Flusberg continues, and ultimately leads to confusion and distress for families.

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