About

Andrea Baccarelli, MD, PhD, is the Dean of the Faculty at the Harvard T.H. Chan School of Public Health and an internationally recognized scientist and thought leader. His pioneering work has transformed understanding of how environmental factors reshape the human epigenome and impact long-term health. Dr. Baccarelli has explored diverse molecular mechanisms, from epitranscriptomics to the microbiome, helping guide public policies and advance global health innovations. He is recognized as one of the world’s most highly cited scientists, with influence spanning research, education, and policy. Before assuming his role as Dean of the Faculty in January 2024, he served as the Leon Hess Professor and Chair of the Department of Environmental Health Sciences at Columbia Mailman School of Public Health and as president of the International Society for Environmental Epidemiology. He previously worked at Harvard Chan School as an Associate Professor from 2010 through 2016. Dr. Baccarelli holds an MD from the University of Perugia in Italy, an MS in Epidemiology from the University of Turin, and a PhD from the University of Milan. His research focuses on the impact of environmental exposures on health, with a particular emphasis on epigenetics and molecular mechanisms influencing disease.

Research topics

• Medicine
• Biology
• Genetics
• Internal medicine
• Bioinformatics
• Physiology
• Environmental health
• Computer Science
• Andrology
• Ecology
• Environmental chemistry
• Risk analysis (engineering)
• Demography
• Environmental science
• Surgery
• Computational biology
• Data science
• Engineering
• Chemistry
• Nursing
• Obstetrics

Selected publications

• CoxMDS: multiple data splitting for high-dimensional mediation analysis with survival outcomes in epigenome-wide studies

  Briefings in Bioinformatics · 2026-01-01

  articleOpen access

  Causal mediation analysis investigates whether the effect of an exposure on an outcome operates through intermediate variables known as mediators. Although progress has been made in high-dimensional mediation analysis, current methods do not reliably control the false discovery rate (FDR) in finite samples, especially when mediators are moderately to highly correlated or follow non-Gaussian distributions. These challenges frequently arise in DNA methylation studies. We introduce CoxMDS, a multiple data splitting method that uses Cox proportional hazards models to identify putative causal mediators for survival outcomes. CoxMDS ensures finite-sample FDR control even in the presence of correlated or non-Gaussian mediators. Through simulations, CoxMDS is shown to maintain FDR control and achieve higher statistical power compared with existing approaches. In applications to DNA methylation data with survival outcomes, CoxMDS identified eight CpG sites in The Cancer Genome Atlas that are consistent with the hypothesis that DNA methylation may mediate the effect of smoking on lung cancer survival, and two CpG sites in the Alzheimer's Disease Neuroimaging Initiative that are consistent with the hypothesis that DNA methylation may mediate the effect of smoking on time to Alzheimer's disease conversion.

  PublisherDOI

• Association between adipokines and glycemia in children under age 8: the PROGRESS cohort of Mexico

  medRxiv · 2026-01-22

  articleSenior author

  Background: The role of adipokines in childhood glycemia is poorly understood. We investigate the longitudinal association between adipokines and glycemia in a cohort of children in Mexico City. Methods: were measured at four, six, and eight years, and fasting insulin at eight years. Adiponectin to leptin ratio (ALR) and HOMA2 indices were computed. Longitudinal associations were examined by linear mixed models and cross-sectional associations were examined by multivariable linear regression. All models were adjusted for maternal and child covariates. Findings: Between ages four and eight years, average levels of leptin increased from 3·2 to 10·8 ug/mL; adiponectin dropped from 15·7 to 13·7 ng/mL; and ALR dropped from 9·1 to 3·1 ug/ng. Longitudinally, across timepoints four, six, and eight years after birth, there was no association between adipokines and glycemia. However, the cross-sectional analysis at age 8 years found an association between leptin and insulin (1·0, 95% CI: 1·0; 1·1), HOMA2-B (1·0, 95% CI: 1·0; 1·0), HOMA2-IR (1·0, 95% CI: 1·0; 1·1), and HOMA2-S (0·9, 95% CI: 0·9; 0·9). Interpretation: Further investigation is needed to understand the role of adipokines in the development of T2DM in children and the factors that may alter adipokine metabolism.

  PublisherDOI

• Evaluation of the evidence on acetaminophen use and neurodevelopmental disorders using the Navigation Guide methodology

  Environmental Health · 2025-08-13 · 48 citations

  reviewOpen accessSenior authorCorresponding

  BACKGROUND: Acetaminophen is the most commonly used over-the-counter pain and fever medication taken during pregnancy, with > 50% of pregnant women using acetaminophen worldwide. Numerous well-designed studies have indicated that pregnant mothers exposed to acetaminophen have children diagnosed with neurodevelopmental disorders (NDDs), including autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD), at higher rates than children of pregnant mothers who were not exposed to acetaminophen. METHODS: We applied the Navigation Guide methodology to the scientific literature to comprehensively and objectively examine the association between prenatal acetaminophen exposure and NDDs and related symptomology in offspring. We conducted a systematic PubMed search through February 25, 2025, using predefined inclusion criteria and rated studies based on risk of bias and strength of evidence. Due to substantial heterogeneity, we opted for a qualitative synthesis, consistent with the Navigation Guide's focus on environmental health evidence. RESULTS: We identified 46 studies for inclusion in our analysis. Of these, 27 studies reported positive associations (significant links to NDDs), 9 showed null associations (no significant link), and 4 indicated negative associations (protective effects). 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. CONCLUSIONS: Our analyses using the Navigation Guide thus support evidence consistent with an association between acetaminophen exposure during pregnancy and increased incidence of NDDs. Appropriate and immediate steps should be taken to advise pregnant women to limit acetaminophen consumption to protect their offspring's neurodevelopment.

  PublisherOA PDFDOI

• Epigenome-wide association study meta-analysis of wellbeing

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-09-12 · 1 citations

  preprintOpen access

  Abstract Wellbeing is associated with both behavioral phenotypes as well as several key life outcomes, such as health, employment, and coping with stressful events. These phenotypes associated with wellbeing could be potential indicators of differential epigenetic patterns between individuals that differ in their levels of wellbeing. We performed the largest epigenome-wide (EWAS) meta-analysis of wellbeing to date by combining whole blood DNA methylation data (Illumina 450k array) from 13 cohorts from Europe, Australia, and the USA ( N = 10,757 participants). After correcting for smoking and BMI, no epigenome-wide significant methylation sites were identified. We tested whether a weighted methylation score (MS) based on leave-one-cohort-out EWAS meta-analysis summary statistics predicted wellbeing in an independent cohort, and whether prediction was significant over and above the polygenic score (PGS) for wellbeing. The MS was associated with wellbeing (variance explained=0.22%, p =0.03) and was no longer significant after adding the polygenic score (PGS; variance explained=0.43%, p =0.0046, MS; variance explained=0.07%, p =0.2842). We further compared DNA methylation levels in 16 pairs of monozygotic twins discordant for wellbeing. These analyses revealed no significant within-pair DNA methylation differences at the top-sites from the meta-analysis or in MS. Our results suggest that larger EWAS meta-analyses with uniform phenotype assessment are required to identify methylation sites associated with wellbeing.

  PublisherOA PDFDOI

• Social factors as buffers for the adverse impact of adverse childhood experiences on biological age acceleration among adults in Hispanic Community Health Study / Study of Latinos

  Brain Behavior and Immunity · 2025-12-22

  articleOpen access
  PublisherOA PDFDOI

• Threats and humiliation at the workplace and mental health among environmental scientists - a cross-sectional study

  SSM - Mental Health · 2025-12-19

  articleOpen accessSenior author

  Violence at the workplace (e.g., threats, humiliation) is an increasing area of concern in many countries around the world. This study aimed to quantify the prevalence of mental health conditions associated with workplace violence among environmental health professionals. We conducted a cross-sectional survey between January and February 2022 among scientists who are members and former members of the International Society for Environmental Epidemiology (ISEE). Of those contacted, 627 participated (32.9%), comprising 64.4% females (n = 397) and 35.6% males (n = 219), of those n = 500 (64.2% females, 35.8% males) could be included in the analyses. To analyse associations between threats and humiliation at the workplace and depression, anxiety, and stress, we used generalized linear models. Most participants (70.2%) were 31 – 60 years old and from North America (48.4%). Of those, 15.0% reported poor health, 17.0% depression, 24.7% anxiety, and 31.9% stress. Threats and humiliation were commonly reported at the workplace, threats reported by 77.4% of females and 56% of males, and humiliation reported by 77.4% of females and 68.9% of males. Joint reporting of threats and humiliation was most common among females, and humiliation was most commonly reported among younger and older scientists. Reporting of threats and humiliation was significantly negatively associated with health, depression, anxiety, and stress. The findings suggest that 1) violence at the workplace should be investigated more, 2) threats and humiliation at the workplace should be a target of policies and politics to reduce not only the suffering of those affected but also economic loss due to reduced health of workers. • Almost half of environmental health professionals reported threats, and two-thirds reported humiliation at the workplace. • Perceived threats and humiliation at the workplace are more frequent among females and younger and older age groups. • Perceived threats and humiliation at the workplace were associated with increased rates ofdepression and stress symptoms. The strongest associations between perceived threats and harassment were found with reported social exclusion, being advised to quit, and being prevented from publishing • Health of the working population is associated with threats, harassment, and humiliation at the workplace.

  PublisherDOI

• Diet Quality and Epigenetic Aging in the Women’s Health Initiative

  UNC Libraries · 2025-10-22

  articleOpen access
  PublisherDOI

• Extracellular vesicle-encapsulated microRNA signatures of cigarette smoking and smoking-related harm

  Respiratory Medicine · 2025-07-01 · 2 citations

  article
  PublisherDOI

• Impact of a prenatal exposure mixture of metals on DNA methylation-derived cell-type composition in cord blood

  Current Zoology · 2025-12-16 · 2 citations

  articleOpen access

  Abstract Metal(loid) exposure can exert immunotoxic effects, including changes in white blood cell proportions. The impact from metal exposure mixtures during pregnancy has not been examined in relation to cell-type composition at birth. Our aim was to evaluate the associations between a prenatal metal(loid) exposure mixture and cord blood DNA methylation-derived cell-type composition. We leveraged the PROGRESS birth cohort with measured prenatal immunotoxic metal(loid)s in blood (manganese, lead) and urine (arsenic, cadmium) and DNA methylation-derived cell-type composition from cord blood (n = 428). We used the novel Dirichlet Bayesian Weighted Quantile Sum regression to elucidate the association of metal mixtures on a compositional outcome with several DNA methylation-derived cell types: granulocytes (GR), CD4+ and CD8+ T-cells, B-cells, monocytes, natural killer (NK) cells, and nucleated red blood cells (nRBCs). We also conducted stratified analyses by fetal sex. We observed no associations in the overall population. In sex-stratified models, a one-quartile increase in metal mixture among the pregnant women carrying a female was associated with a 4.85% [95% credible intervals (CrI): 1.11%, 8.81%] increase in GR proportion, driven by arsenic. Conversely, a one-quartile increase in metal mixture in women carrying a male was marginally associated with a 3.44% (95% CrI: −7.08%, 0.37%; 80%CrI: −5.83%, −1.01%) decrease in GR proportion, driven by cadmium. We also observed marginal metal mixture associations with higher proportions of CD8+ T-cells in women carrying a male and lower proportion of NK cells and nRBCs in women carrying a female. Our findings suggest a potential differential metal mixture-cell composition associations given by fetal sex.

  PublisherOA PDFDOI

• Associations of Legacy and Emerging Halogenated Flame Retardant Exposures with Childhood Attention Deficit/Hyperactivity Disorder-Related Traits and Brain Functional Connectivity in a Canadian Birth Cohort

  Environmental Science & Technology · 2025-10-01 · 1 citations

  article

  Halogenated flame retardants (HFRs) are widely used chemicals with potential neurotoxicity, yet limited epidemiologic evidence exists for their association with childhood neurodevelopment. We investigated associations between HFR exposures and attention-deficit/hyperactivity disorder (ADHD)-related traits and brain functional connectivity in 194 children aged 8-12 years from the GESTation and Environment (GESTE) birth cohort in Sherbrooke, Canada. We assessed 16 legacy and emerging HFRs in plasma and stool, with 5 in plasma and 9 in stool samples included in the final analysis. ADHD-related traits were assessed using behavioral questionnaires and the Conners Continuous Performance Test. Resting-state functional magnetic resonance imaging was used to assess brain functional connectivity in four ADHD-relevant brain networks. We applied covariate-adjusted linear regression models to examine associations between HFRs and outcomes, applying a false discovery rate correction of 0.1 for multiple comparisons. Several nominally significant associations were identified before correction, including a positive association between anti-DP and attention problems, negative associations between Dec602 and hyperactivity, and BB153 and hit reaction time variability. However, none remained significant after multiple comparison correction. Overall, we observed no significant associations between HFR concentrations in plasma or stool and ADHD-related traits or brain functional connectivity, suggesting that there is limited evidence for a link between them.

  PublisherDOI

Recent grants

• NIH Grant R01ES021357

  NIH · $3.3M · 2018

• NIH Grant R21ES021895

  NIH · $376k · 2015

• Effects of Flame Retardants on Brain Function and Attentional Deficits in School-age Children - Brain Imaging, Neurobehavioral, and Gut Microbiome Studies in a Longitudinal Birth Cohort

  NIH · $2.7M · 2018–2023

• Community Engagement Core

  NIH · $39.2M · 1998–2028

• NIH Grant R21ES019773

  NIH · $425k · 2013

Frequent coauthors

• Lifang Hou

  Northwestern University

  535 shared

• Pier Alberto Bertazzi

  489 shared

• Pantel Vokonas

  Boston University

  479 shared

• Joel Schwartz

  Harvard University

  387 shared

• Letizia Tarantini

  University of Milan

  344 shared

• Valentina Bollati

  University of Milan

  328 shared

• Robert O. Wright

  298 shared

• David Sparrow

  VA Boston Healthcare System

  263 shared

Education

• PhD, Environmental and Occupational Health

  University of Milan

  2003

• MPH, Epidemiology

  University of Turin

  1999

• MD, Medicine

  University of Perugia

  1995

Awards & honors

• Elected to the National Academy of Medicine