Health and Human Services Secretary Robert F. Kennedy Jr. raised the alarm earlier this year about the meteoric rise of reported autism cases in the United States, underscoring at a press conference, "We are doing this to our children, and we need to put an end to it."

"The [autism spectrum disorder] prevalence rate in 8-year-olds is now 1 in 31," said Kennedy, referring to a study that examined children born in 2014. The health secretary noted further that American boys face an "extreme risk" of ending up with autism, stating that they have a 1 in 20 chance of being diagnosed with the condition — or a 1 in 12.5 chance in California.

Kennedy promised President Donald Trump during a Cabinet meeting in April that "by September, we will know what has caused the autism epidemic and we'll be able to eliminate those exposures."

A study published this month in the peer-reviewed medical journal BMC Environmental Health could prove valuable to the Department of Health and Human Services' campaign to narrow down the possible causes of autism.

Researchers from the Harvard T.H. Chan School of Public Health, University of California Los Angeles' School of Public Health, and the Icahn School of Medicine at Mount Sinai systematically reviewed 46 "well-designed" studies incorporating data from over 100,000 participants regarding the relationship between neurodevelopmental disorders, including autism and attention-deficit/hyperactivity disorder, and prenatal exposure to acetaminophen.

'The research team’s findings strengthen the evidence for a connection and raise concerns about current clinical practices.'

Acetaminophen, the drug sold under the brand Tylenol in the United States and Canada, is the most common over-the-counter pain and fever medication used during pregnancy and is reportedly used by well over 50% of pregnant women worldwide.

The researchers found that 27 of the studies reported "significant links" between acetaminophen exposure in the womb and NDDs and noted that "higher-quality studies were more likely to show positive associations."

"Overall, the majority of the studies reported positive associations of prenatal acetaminophen use with ADHD, ASD, or NDDs in offspring, with risk-of-bias and strength-of-evidence ratings informing the overall synthesis," said the study.

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When specifically evaluating the studies pertaining to Tylenol use and autism in children, the researchers found "strong evidence of a relationship between prenatal acetaminophen use and increased risk of ASD in children."

The drug freely crosses the placental barrier, "reaching levels in fetal circulation similar to maternal circulation within less than an hour of maternal ingestion."

According to the researchers, the drug:

• "undergoes oxidative metabolism via the enzyme CYP2E1 — present in fetal brains, placenta, and lungs — to produce toxic metabolites";
• "affects prostaglandin and endocannabinoid pathways, which are involved in prenatal neuronal development";
• has been shown in animal models to increase "oxidative stress markers in the fetal brain and is associated with neurodevelopmental deficits"; and
• "directly perturbs hormone-dependent processes, affects neurodevelopment and reproductive disorders, and might alter steroidogenesis in the placenta and induce placental damage."

Dr. Diddier Prada, an assistant professor at the Icahn School of Medicine at Mount Sinai, said in a release, "Our findings show that higher-quality studies are more likely to show a link between prenatal acetaminophen exposure and increased risks of autism and ADHD."

"Given the widespread use of this medication, even a small increase in risk could have major public health implications," added Prada.

Mount Sinai noted that while the damning study "does not show that acetaminophen directly causes neurodevelopmental disorders," "the research team’s findings strengthen the evidence for a connection and raise concerns about current clinical practices."

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The medical community has long raised concern about the possible downsides of acetaminophen consumption during pregnancy.

An international coalition of public health experts said in a consensus statement published on Sept. 23, 2021, in the journal Nature Reviews Endocrinology that "increasing experimental and epidemiological research suggests that prenatal exposure to APAP [acetaminophen] might alter fetal development, which could increase the risks of some neurodevelopmental, reproductive, and urogenital disorders."

'This work is ongoing, and the department will follow the science wherever it leads.'

"Epidemiological studies consistently suggest prenatal APAP exposure might increase the risk of adverse neurodevelopmental and behavioral outcomes, such as attention deficit hyperactivity disorder (ADHD), autism spectrum disorder, language delay (in girls) and decreased intelligence quotient," said the experts. "Collectively, the studies suggest that the timing and duration of maternal APAP use are critical factors."

HHS press secretary Emily Hilliard told Blaze News that HHS does not comment on outside studies. Hilliard noted, however, that "under Secretary Kennedy’s leadership, HHS is taking action guided by gold-standard, evidence-based science. This work is ongoing, and the department will follow the science wherever it leads."

Tylenol does not appear to be particularly pleased with the study.

A company spokesperson for Kenvue, the maker of Tylenol, said in a statement to Blaze News, "Nothing is more important to us than the health and safety of the people who use our products. We continue to evaluate the science, and this study does not change our view that there is no causal link between acetaminophen use during pregnancy and fetal developmental issues."

"To date, the U.S. Food and Drug Administration and leading medical organizations agree on the safety of acetaminophen, its use during pregnancy, and the information provided on the label," added the spokesperson.

A source close to Tylenol noted further that "it appears the study was designed for litigation and not public health, as two of the authors are experts for the plaintiffs in the acetaminophen litigation."

Harvard University's Dr. Andrea Baccarelli, one of the authors on the study, served as an expert witness on matters of general causation involving acetaminophen use during pregnancy in a multi-district litigation class-action lawsuit against Tylenol.

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