Most medico-legal controversies over causation resolve in the pages of medical journals and within the walls of state and federal courthouses. The claim that pregnant women’s ingestion of acetaminophen causes their children to have an increased risk of autism, however, has become a flash point in American political drama.[1]
After the district court entered judgment against plaintiffs in the acetaminophen MDL, a sea change in the politicization of science occurred in the executive branch of the United States. In November 2024, the United States returned Donald Trump, its first fully post-modern president to office. For most of his life, Trump, in an homage to Michel Foucault, has seen no difference between assertions and truth. In the run up to the general election of 2024, Trump forged an alliance with independent candidate Robert F. Kennedy, Jr., whose disdain for evidence and truth has long made him a notorious source of misinformation on vaccines, autism, antidepressants, pesticides, glyphosate, among other things.
In August 2024, Kennedy quit his campaign and endorsed Trump, in return for a role in a future Trump Administration. After promising Kennedy a cabinet level position, Trump told his supporters that: “I’m going to let him go wild on health. I’m going to let him go wild on the food. I’m going to let him go wild on the medicines.”[2] Trump kept his promise of an appointment to Kennedy. On February 13, 2025, Robert F. Kennedy Jr. was confirmed by a narrow vote of the Senate, and sworn in as Secretary of Health and Human Services. President Trump immediately issued Executive Order 14211 to establish a “Make America Healthy Again [MAHA] Commission,” to be chaired by Secretary Kennedy.[3] One of the key objectives of the MAHA commission included investigating the causes of chronic childhood diseases and “assess[ing] the prevalence of and threat posed by the prescription of selective serotonin reuptake inhibitors, antipsychotics, mood stabilizers, stimulants, and weight-loss drugs.”
Two months later, at a press conference in April 2025, Kennedy asserted that environmental toxic substances were responsible for the increasing prevalence of autism. Only a day earlier, the Centers for Disease Control issued a report in which over 50 government scientists explained that evolving diagnostic criteria and improved awareness of parents and teachers (not to mention entitlements to social and educational support) were largely responsible for the changing patterns of diagnosis and assessment.[4]
Channeling his lawsuit industry practice in which Kennedy labeled any adverse evidence as a manufacturing industry conspiracy, the Secretary dismissed the CDC’s explanations as a (manufacturing) industry “canard” to deflect attention from possible environmental causes. Kennedy promised a massive research initiative to identify the environmental “culprit,” with results to be available by September 2025.[5]
The scientific community might well have been skeptical about how Kennedy was going to deliver answers to etiological questions surrounding autism in five months, when causal conclusions had eluded the scientific world for decades. In the fullness of the next five months, not much new research was done, but with the clock ticking, a conclusion was launched in the absence of evidence.
On September 22, 2025, President Trump, along with Secretary Kennedy, FDA Commissioner Marty Makary, Director of the National Institutes of Health Jay Bhattacharya, and Administrator of the Centers for Medicare & Medicaid Services Mehmet Oz, called a news conference to announce the “conclusion.”[6] Stumbling over the pronunciation of acetaminophen, Trump told women not to take the medication; it caused autism. Kennedy struck a more moderate note about acetaminophen, in describing a “potential” association between acetaminophen and ASD and ADHD. He acknowledged reviewing “contrary” studies showing no association, and announced that the FDA would issue a notice to physicians and begin a change in the medication label.
When Commissioner Makary spoke, he cited studies showing “consistent” associations between acetaminophen and autism. In a flourish, Makary stated that:
“four weeks ago, a Mount Sinai Harvard study [“Pada 2025”] reviewed all the existing literature and found the overwhelming body of evidence points to an association. Sure, you’ll be able to find a study to the contrary, that’s how science works, but to quote the dean of the Harvard School of Public Health, there is a causal relationship between prenatal acetaminophen use and neurodevelopmental disorders of ADHD and autism spectrum disorder.”[7]
The dean referenced by Makary was none other than Andrea Baccarelli, the key expert witness for plaintiffs’ in the acetaminophen MDL, who was excluded by Judge Denise Cote’s Rule 702 decision. Baccarelli has only recently moved from Columbia University to assume a new position at Harvard. The Mount Sinai study published four weeks earlier was a review by four authors, including Baccarelli.[8] Baccarelli and his co-authors, however, decidedly did not embrace a causal conclusion in their publication. In their statement of conclusions in the paper’s abstract, Baccarelli and his co-authors stated that their “analyses using the Navigation Guide thus support evidence consistent with an association between acetaminophen exposure during pregnancy and increased incidence of NDDs.” (emphasis added). In the discussion section of their paper, the authors explained that their “analysis demonstrated evidence consistent with an association between exposure to acetaminophen during pregnancy and offspring with NDDs, including ASD and ADHD, though observational limitations preclude definitive causation.”[9] In his press conference remarks, Makary was quoting not from a peer-reviewed article, but from Baccarelli’s expert witness report, written for litigation, and excluded from evidence by Judge Cote’s decision in 2023.
Makary’s reference to language from Baccarelli’s 2023 expert witness litigation report thus raises two interesting questions. First, given that expert witness reports do not generally find their way to the desks of the FDA Commissioner, how did Makary come by this plaintiffs’ litigation report? Second, and more troubling, why did Baccarelli defend his causal conclusion under oath, at an examination before trial in 2023,[10] when he was unwilling to embrace a causal conclusion two years later, in 2025? The first question raises at least the appearance of collusion between the lawsuit industry and political actors such as Secretary Kennedy and Commissioner Makary. The second question raises the issue of fraud on the court by a witness who is willing to assert a causal conclusion in legal proceedings, but is not willing to publish and defend the causal conclusion to his peers in a scientific journal.
In the wake of the news conference, the New York Times talked with Baccarelli, and reported that he opined in the interview that “[f]urther research is needed to confirm the association and determine causality, but based on existing evidence, I believe that caution about acetaminophen use during pregnancy — especially heavy or prolonged use — is warranted.”[11] In essence, Baccarelli was offering a precautionary principle interpretation of the available evidence, not a causal conclusion. Baccarelli issued a statement on social media, the day of the news conference, to state that he and his colleagues “had conducted a rigorous review funded by a grant from the National Institutes of Health (NIH), of the potential risks of acetaminophen use during pregnancy.” Baccarelli disclaimed having reached a causal conclusion, describing his review as showing merely “evidence of an association between exposure to acetaminophen during pregnancy and increased incidence of neurodevelopmental disorders in children,” and that “[f]urther research is needed to confirm the association and determine causality….”[12] As we will see, Baccarelli’s claim that the Prada review was funded by an NIH grant was a bit of a tall tale, but his disclaiming a causal conclusion and explaining that his position was based upon the precautionary principle, not a showing of medical causation, was both candid and at odds with his litigation expert report.
The lead author of the Prada Review, Diddier Prada, an epidemiologist at Mount Sinai Hospital in New York, similarly told the Times that “[w]e cannot answer the question about causation — that is very important to clarify.”[13] A third author of the Prada Review was Ann Bauer, the lead author of the 2021 putative consensus paper that was instrumental in starting the acetaminophen mass tort. Bauer commented in advance of the September press conference. In anticipating the Administration’s embrace of a causal claim, Bauer noted that she was “a little concerned about how this message is going to come because I think they may be jumping the gun”; “I think those of us in the research community would like to see stronger evidence.”[14]
Scientific Community’s Reaction to Trump’s News Conference
Trump’s press conference on acetaminophen and vaccines was widely met with condemnation and disbelief.[15] Most medical organizations were appalled at the administration’s sloppy messaging. The day after the press conference, the American College of Medical Toxicology (ACMT) issued a statement in response, to affirm the safety of acetaminophen in pregnancy. The ACMT noted that its position agreed with those of the American College of Obstetrics and Gynecologists, the Society for Maternal-Fetal Medicine, the American Academy of Pediatrics, and the Society for Developmental and Behavioral Pediatrics.[16]
In Europe, where pharmaceutical regulation is typically even more precautionary than in the United States, the European Medicines Agency (EMA) announced, a day after the Trump news conference, that using acetaminophen during pregnancy was safe, with no showing that it causes autism in offspring. The EMA announcement quoted Steffen Thirstrup, the EMA’s Chief Medical Officer, as stating that “[p]aracetamol remains an important option to treat pain or fever in pregnant women. Our advice is based on a rigorous assessment of the available scientific data and we have found no evidence that taking paracetamol during pregnancy causes autism in children.”[17] In the United Kingdom, the governmental Medicines & Healthcare Products Regulatory Agency issued a notice, on September 23, 2025, that acetaminophen was safe to take in pregnancy and that the medication has not been shown to cause autism in children.[18]
The day of the news conference, the Autism Science Foundation issued a statement of deep concern about Trump’s announcement. The Foundation observed that “[b]ased on the existing data, there is not sufficient evidence to support a link between acetaminophen and autism.”[19] Medical ethicist Dr. Professor Arthur Caplan, who is not given to hyperbole, called the conference “the saddest display of a lack of evidence, rumors, recycling old myths, lousy advice, outright lies, and dangerous advice I have ever witnessed by anyone in authority.”[20]
The official governmental messaging in the wake of Trump’s press conference was more circumspect. In her press release on the day of the news conference, Press Secretary Karoline Leavitt used the meaningless locution, “suggested link,” and cited the Prada review, which eschewed causal conclusions.[21] Leavitt gratuitously added that “[t]he Trump Administration does not believe popping more pills is always the answer for better health.” Unless of course, it is Propecia for Donald Trump, testosterone for Peter Hegseth, or ketamine for Elon Musk.
When the administration physicians communicated with the public, they said something very different from Trump’s presentation. Dr. Mehmet Oz, former surgeon and television talking head, who stood mute by Trump’s side, found his voice later in the week, when he acknowledged that pregnant women of course should take acetaminophen when physicians direct them to do so.[22]
When FDA Commissioner Makary issued a notice to physicians, the same day as the Trump news conference, he carefully avoided causal language:
“In recent years, evidence has accumulated suggesting that the use of acetaminophen by pregnant women may be associated with an increased risk of neurological conditions such as autism and ADHD in children.
* * *
To be clear, while an association between acetaminophen and autism has been described in many studies, a causal relationship has not been established and there are contrary studies in the scientific literature.”[23]
An FDA news release, also on September 22, 2025, announced that the agency was beginning a change in safety labeling, but the agency press release spoke only in terms of association and correlation, and like the FDA notice to physicians, explicitly disavowed a causal conclusion.[24] The FDA also noted that it was undertaking a safety label change, but the official communication did not reveal the dodgy origins of this initiative. The impetus for the label change appears to have come not from FDA scientists, but from Aaron Siri, a plaintiff’s lawyer who worked in concert with Robert Kennedy for years in anti-vaccination litigation. In a remarkable coincidence, Siri filed a citizen’s petition with the FDA, the same day of Trump’s news conference to raise “exigent concerns” over a need for a label change.[25] The New York Times noted some of the troubling ethical concerns raised by Siri’s parallel activities. In 2023, Siri’s law firm recruited plaintiffs for acetaminophen mass tort litigation. In 2024, Siri represented Kennedy in his election campaign.[26] The week before the Trump news conference, Jill Schoff, an employee of Siri’s law firm, uploaded Baccarelli’s expert witness report from the acetaminophen MDL to the Internet Archive, which explains how Dr. Makary was able to quote from its conclusions at the September 22nd news conference.[27] Siri cited to Baccarelli’s for-litigation report, at the Internet Archive, in his citizen’s petition that plumped for a label change.
The politicization of the acetaminophen issue appeared to be complete, when a month after Trump’s press conference, Trump sycophant and Texas Attorney General Ken Paxton sued manufacturers of acetaminophen for “deceptively marketing Tylenol to pregnant mothers despite knowing that early exposure to acetaminophen, Tylenol’s only active ingredient, leads to a significantly increased risk of autism and other disorders.”[28] Only a month earlier, the FDA acknowledged in its press release and its notice to physicians, that causation was not known. Paxton filed the complaint in Panola County, Texas, where Trump received 81.4% of the counted votes in 2024.[29] In addition to lawyers at the Office of the Texas Attorney General, Ashley Keller and others from the Keller Postman LLC firm were listed as representing Texas in its epistemic and scientific overclaiming. Ashley Keller was the principal lawyer for plaintiffs in the MDL, which had been dismissed by Judge Cote in 2024.
(to be continued)
[1] I am indebted to, and thank, Barbara McIntyre for sharing some of the research for this series.
[2] Brett Samuels, Trump says he’ll let RFK Jr. ‘go wild’ on health and food in potential second term, THE HILL (Oct. 27, 2024), available at https://thehill.com/homenews/campaign/4956319-trump-says-hell-let-rfk-jr-go-wild-on-health-and-food-in-potential-second-term/.
[3] Executive Order 14211, Establishing the President’s Make America Healthy Again Commission”. The White House (Feb. 13, 2025), available at https://www.whitehouse.gov/presidential-actions/2025/02/establishing-the-presidents-make-america-healthy-again-commission/.
[4] Kelly A. Shaw, et al., Prevalence and Early Identification of Autism Spectrum Disorder Among Children Aged 4 and 8 Years — Autism and Developmental Disabilities Monitoring Network, 16 Sites, United States, 2022, 74 MORBIDITY & MORTALITY WEEKLY REP. 1 (Apr. 17, 2025).
[5] Meredith Wadman, Claiming autism ‘epidemic,’ RFK Jr. describes NIH initiative to find environmental causes, SCIENCE (Apr. 16, 2025), available at https://www.science.org/content/article/claiming-autism-epidemic-rfk-jr-describes-nih-initiative-find-environmental-causes
[6] Transcript, News Conference – Remarks: Donald Trump Makes an Autism Announcement at the White House, ROLLCALL (Sept. 22, 2025), available at
https://rollcall.com/factbase/trump/transcript/donald-trump-remarks-health-autism-white-house-september-22-2025/ (Transcript).
[7] Transcript at 24:35.
[8] Diddier Prada, Beate Ritz, Ann Z. Bauer and Andrea A. Baccarelli, “Evaluation of the evidence on acetaminophen use and neurodevelopmental disorders using the Navigation Guide methodology,” 24 ENVT’L HEALTH 56 (2025) [Prada]
[9] Prada Review at 38.
[10] Notes of Testimony from Deposition of Andrea Baccarelli, In re Acetaminophen ASD-ADHD Prods. Liab. Litig., Case No. 1:22-md-03043-DLC (Aug. 14, 2023).
[11] Azeen Ghorayshi, Trump Issues Warning Based on Unproven Link Between Tylenol and Autism, N.Y. TIMES (Sept. 22, 2025), available at https://www.nytimes.com/2025/09/22/health/kennedy-autism-tylenol-trump.html?searchResultPosition=2
[12] Statement from Andrea Baccarelli on X (Sept. 22, 2025), available at https://x.com/RapidResponse47/status/197023187271541578.
[13] Id.
[14] Jon Hamilton, Yuki Noguchi & Nell Greenfieldboyce, Trump blames Tylenol for autism. Science doesn’t back him up, NAT. PUBLIC RADIO (Sept. 22, 2025) (quoting Dr. Bauer), available at https://www.npr.org/sections/shots-health-news/2025/09/22/nx-s1-5550153/trump-rfk-autism- tylenol-leucovorin- pregnancy#:~:text=Many%20physicians%20and%20autism%20advocacy,studies%20in%20the %20scientific%20literature.%22
[15] Jeff Mason, Ahmed Aboulenein, and Julie Steenhuysen, Trump Links Autism to Tylenol and Vaccines, Claims Not Backed by Science, REUTERS (Sept. 22, 2025) (quoting Britain’s health regulator as saying that using paracetamol was safe and that there is no evidence paracetamol caused autism in children; quoting Coalition of Autism Scientists as stating that “[t]he data cited do not support the claim that Tylenol causes autism … .”) available at https://www.reuters.com/business/healthcare-pharmaceuticals/trump-expected-link-autism-with-tylenol-experts-say-more-research-needed-2025-09-22/; Brianna Abbott & Andrea Petersen, The Trump administration said acetaminophen could cause autism. Doctors maintain it is safe during pregnancy, WALL ST. J. (Sept. 22, 2025) (“Doctors and medical societies say acetaminophen, the active ingredient in Tylenol, remains the best option for treating fever and pain during pregnancy”), available at https://www.wsj.com/politics/policy/tylenol-pregnancy-autism-trump-report-what-to-know-2873d8e1; Will Weissert, Dr. Trump? The president reprises his COVID era, this time sharing unproven medical advice on autism, ASSOC. PRESS NEWS (Sept. 23, 2025), available at https://apnews.com/article/trump-doctor-vaccines-autism-tylenol-covid-disinfectants-22f5bcfe2fd3c18fdd412419941541f8; Editorial Board, ‘I’m not a doctor’: This shoddy autism science helps no one; President Donald Trump’s rant on vaccines and Tylenol has no basis in fact, WASH. POST (Sept. 22, 2025), available at https://www.washingtonpost.com/opinions/2025/09/22/trump-autism-vaccines-tylenol-acetaminophen/; Vivian Ho & Karla Adam, WHO joins global health leaders rejecting U.S. acetaminophen warnings; The World Health Organization is the latest to criticize claims from President Donald Trump and Robert F. Kennedy Jr. linking autism to Tylenol use during pregnancy, WASH. POST (Sept. 24, 2025), available at https://www.washingtonpost.com/health/2025/09/24/paracetamol-acetaminophen-tylenol-autism-who-trump/; Ariana Eunjung Cha, Matt Viser & Dan Diamond, As Trump ties Tylenol to autism, doctors raise alarms; U.S. officials will issue a warning label for pregnant individuals — a move that contradicts the guidance from the major medical societies, WASH. POST (Sept. 23, 2025), available at https://www.washingtonpost.com/health/2025/09/22/tylenol-autism-trump-announcement/
[16] American College of Medical Toxicology, ACMT Position Statement: ACMT Supports the Safe Use of Acetaminophen in Pregnancy (Sept. 23, 2025), available at https://www.acmt.net/news/acmt-position-statement-acmt-supports-the-safe-use-of-acetaminophen-in-pregnancy/
[17] European Medicines Agency, Use of paracetamol during pregnancy unchanged in the EU (Sept. 23, 2025), available at https://www.ema.europa.eu/en/news/use-paracetamol-during-pregnancy-unchanged-eu
[18] Medicines & Healthcare Products Regulatory Agency, MHRA confirms taking paracetamol during pregnancy remains safe and there is no evidence it causes autism in children (Sept. 23, 2025), available at https://www.gov.uk/government/news/mhra-confirms-taking-paracetamol-during-pregnancy-remains-safe-and-there-is-no-evidence-it-causes-autism-in-children.
[19] Autism Science Foundation, Statement on White House Announcement on Autism (Sept. 22, 2025), available at
https://autismsciencefoundation.org/press_releases/asf-statement-wh-briefing/.
[20] Ali Swenson & Lauran Neergaard, “Trump makes unfounded claims about Tylenol and repeats discredited link between vaccines and autism,” ASSOC. PRESS (Sept. 23, 2025) (quoting Prof. Caplan), available at https://apnews.com/article/tylenol-cause-autism-trump-kennedy-0847ee76eedecbd5e9baa6888b567d66
[21] Karoline Leavitt, “FACT: Evidence Suggests Link Between Acetaminophen, Autism,” WHITE HOUSE (Sept. 22, 2025), available at https://www.whitehouse.gov/releases/2025/09/fact-evidence-suggests-link-between-acetaminophen-autism/
[22] Sara Moniuszko & Céline Gounder, Dr. Oz says “of course” pregnant women should take Tylenol if a doctor says so (Sept. 26, 2025), available at https://www.cbsnews.com/news/dr-oz-says-of-course-pregnant-women-should-take-tylenol-if-a-doctor-says-so/
[23] Martin A. Makary, Notice to Physicians on the Use of Acetaminophen During Pregnancy, (Sept. 22, 2025) (emphasis added), available at https://www.fda.gov/media/188843/download?attachment=&utm_medium=email&utm_source=govdelivery
[24] FDA News Release, FDA Responds to Evidence of Possible Association Between Autism and Acetaminophen Use During Pregnancy (Sept. 22, 2025), available at https://www.fda.gov/news-events/press-announcements/fda-responds-evidence-possible-association-between-autism-and-acetaminophen-use-during-pregnancy.
[25] Informed Consent Action Network, Citizen Petition regarding safety-related labeling changes for the use of over-the-counter acetaminophen drug products during pregnancy, (Sept. 22, 2025), available at https://static01.nyt.com/newsgraphics/documenttools/88fe67f3f222ab88/66655cc8-full.pdf
[26] Christina Jewett, Kennedy’s Ties to Ally Leading Vaccine Lawsuits Raise Ethical Concerns, N.Y. TIMES (Oct. 3, 2025), available at https://www.nytimes.com/2025/10/03/health/kennedy-aaron-siri-vaccines-lawsuits.html
[27] Andrea Baccarelli, Rule 26 Witness Report, In re Acetaminophen ASD-ADHD Prods. Liab. Litig., Case No. 1:22-md-03043-DLC (Oct. 10, 2023), uploaded to Internet Archive on Sept. 16, 2025, available at https://archive.org/details/baccarelli-expert-report-acetaminophen-asd-adhd.
[28] Office of Texas Attorney General, Press Release: Attorney General Paxton Sues Big Pharma Manufacturers for Deceptively Marketing Tylenol to Pregnant Mothers Despite Known Dangers to Unborn Children (Oct. 28, 2025) (emphasis added), available at https://www.texasattorneygeneral.gov/news/releases/attorney-general-paxton-sues-big-pharma-manufacturers-deceptively-marketing-tylenol-pregnant-mothers.
[29] Panola County, TX Voting, available at https://www.bestplaces.net/voting/county/texas/panola.
