Environmental health sciences, epigenetics, mitochondriomics, and computational epigenomics
Institutions
National Cancer Institute’s Division of Cancer Epidemiology and Genetics Universita' degli Studi di Milano Harvard T.H. Chan School of Public Health Columbia University Mailman School of Public Health
Baccarelli is also well known for his work drawing a link between Tylenol and autism, with the Trump Administration citing his work when advising pregnant women not to take the drug.[3]
He also served as Professor and Chair of the Department of Environmental Health Sciences at the Columbia University Mailman School of Public Health from 2016 to 2023.[6][7] While at Columbia, he led the NIEHS Center for Environmental Health, which brought together scientists, advocates, community organizations and the public to understand health concerns caused by environmental exposures.[8]
Baccarelli has served as the Dean of the Faculty at the Harvard T.H. Chan School of Public Health since January 2024. He previously taught at the Harvard Chan School as the Mark and Catherine Winkler Associate Professor of Environmental Epigenetics from 2010 to 2016.[9]
Deanship at the T. H. Chan Harvard School of Public Health (2024–present)
In January 2024, Baccarelli assumed the role of Dean of the Harvard T.H. Chan School of Public Health. He immediately initiated a yearlong listening tour to engage with faculty and staff, leading to the formation of working groups focused on three strategic areas for the School, i.e., finance, research, and education.[10] Baccarelli also initiated comprehensive reviews of faculty and academic programs aimed at enhancing rigor and quality.[11] Additionally, he has emphasized the importance of cultivating a pluralistic institutional culture aligned with the school's core values and accountable practices.[12]
Facing significant challenges, including substantial federal funding cuts to research programs from the federal government, in early 2025 he introduced a strategic framework emphasizing agility, accessibility, and accountability.[10] His leadership during this period was characterized by transparency and collaboration, as he conducted multiple town hall meetings to address concerns and outline the school's path forward. Faculty members have noted his compassionate and inclusive approach during this crisis.[10]
Research
Baccarelli's research has pioneered the field of public health epigenetics, which explores how environmental factors can modify gene expression without changing the DNA sequence.[13] His studies have demonstrated that air pollution can alter the epigenome, leading to changes in gene regulation that may contribute to the development of diseases such as cardiovascular disorders and neurodegenerative conditions.[14][15]
Baccarelli conducted research showing that short-term exposure to air pollution, including levels considered "acceptable," can impair cognitive ability in the elderly.[16][17][18] Baccarelli also found that the use of nonsteroidal anti-inflammatory drugs such as aspirin partially protected against the negative cognitive effects of pollution.[19] He also conducted research showing that ambient air pollution is associated with an increased risk of osteoporosis and bone fractures in older individuals.[20][21]
In April 2024, Baccarelli authored an opinion article in The Boston Globe, highlighting the scientific advancements related to the exposome, which represents the sum of all environmental and behavioral exposures affecting human health. The article emphasized the potential of DNA methylation and epigenetic analysis to improve public health by identifying and preventing harmful environmental exposures through advanced diagnostic methods.[22]
In 2025, Baccarelli coauthored a systematic review and synthesis that concluded that prenatal acetaminophen (Tylenol) exposure was related to increased risk of neurodevelomental disorders such as autism and ADHD.[23] Shortly after publication, the Trump Administration referenced the paper in a controversial announcement claiming a link between acetaminophen and autism.[24][25]
This is not Baccarelli's first work related to acetaminophen. The study has garnered strong criticism by the scientific community because of its inconsistent methodology and multiple choices that swayed the interpretation of results.[26] Nonetheless, the conclusions of the study by Baccarelli and his colleagues were consistent with a consensus statement published by experts worldwide that also linked prenatal use of acetaminophen with higher risk of child's neurovelopmental disorder.[24]
Expert testimony
In 2023 he was a proposed expert plaintiff witness in a lawsuit against acetaminophen manufacturers. A judge excluded him and other plaintiff witnesses because the experts' bases for their opinions did not meet required court scrutiny.[27] In September 2025, Baccarelli stated that he was paid $150,000 for his work to prepare the comprehensive written report needed to serve as an expert witness in the court case.[28][29] Dr. Bruce Lamphear, a renowned epidemiologist, reported how he routinely encourages scientists to testify in similar cases-as Baccarelli did-as a means to have science influence practice.[30]
Awards and recognition
In 2020, Baccarelli was elected to the National Academy of Medicine.[31] He has also been an active member of the International Society of Environmental Epidemiology, serving as the society's president from 2022 to 2023.[32]
In 2025, Baccarelli was honored with the John Goldsmith Award from the International Society for Environmental Epidemiology (ISEE), the society's highest accolade, recognizing his sustained and outstanding contributions to the knowledge and practice of environmental epidemiology.[36] As part of the award, he was invited to present the John Goldsmith Memorial Lecture at the ISEE annual conference.[36]
↑ Rebecca, Robbins; Ghorayshi, Azeen (September 23, 2025). "Harvard Dean Was Paid $150,000 as an Expert Witness in Tylenol Lawsuits". The New York Times. Retrieved September 26, 2025. Trump administration officials have leaned heavily on Dr. Baccarelli's research in pushing the idea, citing him in the news conference, posting on social media and championing him in a television interview as a highly credentialed expert backing the evidence for an autism-acetaminophen link.
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