About
Joseph Braun is a Professor of Epidemiology and the Director of the Center for Climate, Environment and Health at Brown University School of Public Health. He previously worked as a school nurse in Milwaukee, WI, before earning his master's and doctoral degrees in Epidemiology from the University of North Carolina-Chapel Hill. He completed postdoctoral training in environmental health at the Harvard School of Public Health. For over 15 years, Dr. Braun has dedicated his research to identifying modifiable risk factors of pediatric diseases to improve public health. His work involves studying the health effects of environmental pollutant exposures before conception and during various stages of development, including gestation, infancy, childhood, and adolescence. His research focuses on endocrine disrupting chemicals, toxic metals, obesity, cardiometabolic health, and neurodevelopmental disorders. Dr. Braun's team employs advanced biostatistical techniques to quantify the health effects of chemical mixtures, identify periods of heightened susceptibility, and explore metabolic and epigenetic pathways affected by chemical exposures. He is also involved in developing interventions aimed at preventing chemical exposures and their health impacts in vulnerable populations. His research utilizes three prospective cohort studies in North America—HOME, MIREC, and PEACE—that follow children from before conception through adolescence.
Research topics
- Medicine
- Biology
- Environmental health
- Chemistry
- Computer Science
- Environmental chemistry
- Environmental science
- Endocrinology
- Obstetrics
- Machine Learning
- Internal medicine
- Genetics
- Statistics
- Pathology
- Telecommunications
- Physiology
- Psychiatry
- Virology
- Mathematics
- Developmental psychology
- Evolutionary biology
- Psychology
Selected publications
Itching to know: the Microbiome, Allergic Disease, and Antimicrobial Chemicals
Current Environmental Health Reports · 2026-04-27
articleSenior authorAssociations of the gut microbiome and cardiometabolic risk in adolescence: the HOME study
BMC Medical Genomics · 2026-04-02
articleOpen accessAlterations to the gut microbiome have been linked to cardiometabolic disease, like type 2 diabetes and hypertension, in adults, but few studies have investigated these associations in adolescents. We examined the relation between the gut microbiome and cardiometabolic risk in adolescence and determined whether sex and race/ethnicity modified these associations. In 144 adolescents (age range: 11–14 years) from the Health Outcomes and Measures of the Environment (HOME) Study, we quantified gut microbiome alpha diversity using the Shannon index and species’ relative abundances (i.e., centered log-ratio normalized abundances) in stool DNA that underwent metagenomic sequencing. We assessed adolescent cardiometabolic risk using a cardiometabolic risk summary score, its individual components (i.e., visceral fat, leptin to adiponectin ratio, HOMA-IR, triglyceride to high-density lipoprotein cholesterol ratio, and systolic blood pressure), as well as total cholesterol and hemoglobin A1c. We used linear regression models to estimate covariate-adjusted cross-sectional associations of the Shannon diversity index and species’ relative abundances with cardiometabolic risk, and examine differences in these associations by sex and race/ethnicity. At the species level, the false discovery rate (FDR) correction, with q-value < 0.20, was considered statistically significant. Among all adolescents, a higher Shannon diversity index was associated with lower systolic blood pressure [β: -0.18 (95% CI: -0.35, -0.01)] in covariate-adjusted models. However, the associations of the Shannon diversity index with cardiometabolic risk did not differ significantly by sex or race/ethnicity. Although associations of the relative abundances of species, prevalent in at least 10% of samples, with cardiometabolic risk were not statistically significant tamong all adolescents after correcting for multiple comparisons (qFDR ≥ 0.20), sex modified the association of the relative abundance of Ruminococcus lactaris with HOMA-IR (qinteraction = 0.151), with positive association among females [β: 2.05 (95% CI: 0.93, 3.17), q = 0.155] and suggestive negative association among males [β: -0.84 (95% CI: -1.59, -0.09), q = 0.983]. Associations of the relative abundances of Streptococcus parasanguinis (qinteraction = 0.097), Enterocloster SGB14313 (qinteraction = 0.097), and Alistipes ihumii (qinteraction = 0.097) with total cholesterol also differed between female and male adolescents. We observed differences between adolescents of non-Hispanic black and non-Hispanic white race/ethnicity in the association of the relative abundance of Lachnospira pectinoschiza (qinteraction = 0.028) with total cholesterol. Our findings suggest that the gut microbiome is associated with cardiometabolic risk in adolescence in a sex-specific manner, and may differ by race and ethnicity.
UNC Libraries · 2026-04-21
articleOpen accessFew methods have been used to characterize repeatedly measured biomarkers of chemical mixtures. We applied latent profile analysis (LPA) to serum concentrations of 4 perfluoroalkyl and polyfluoroalkyl substances (PFAS) measured at 4 time points from gestation to age 12 years. We evaluated the relationships between profiles and z scores of height, body mass index, fat mass index, and lean body mass index at age 12 years (n = 218). We compared LPA findings with an alternative approach for cumulative PFAS mixtures using g-computation to estimate the effect of simultaneously increasing the area under the receiver operating characteristic curve (AUC) for all PFAS. We identified 2 profiles: a higher PFAS profile (35% of sample) and a lower PFAS profile (relative to each other), based on their average PFAS concentrations at all time points. The higher PFAS profile had generally lower z scores for all outcomes, with somewhat larger effects for males, though all 95% CIs crossed the null. For example, the higher PFAS profile was associated with a 0.50-unit lower (β = -0.50; 95% CI, -1.07 to 0.08) BMI z score among males but not among females (β = 0.04; 95% CI, -0.45 to 0.54). We observed similar patterns with AUCs. We found that a higher childhood PFAS profile and higher cumulative PFAS mixtures may be associated with altered growth in early adolescence. This article is part of a Special Collection on Environmental Epidemiology.
Environment International · 2025-10-01 · 2 citations
articleOpen accessBACKGROUND: Declines of several common-studied PFAS noted in the U.S. likely reflect policies that successfully reduced long-chained PFAS production and emission such as the EPA PFOA Stewardship Program. Policy impacts on under-studied PFAS and on predictors of PFAS exposure remain unknown. OBJECTIVE: To assess changes in population-levels and exposure predictors of 10 PFAS in the Boston Birth Cohort (BBC) by Stewardship timelines. MATERIALS AND METHODS: In 1,288 BBC mothers who delivered 1999-2016, the current study focused on 10 PFAS in plasma samples collected 24-72 h postpartum. We estimated PFAS percent differences (%Δ), stratified by the Stewardship timelines. We evaluated predictors related to sources, vulnerability, blood-loss, and diet during pregnancy. RESULTS: The majority of participants were Black (65 %); 8 PFAS were commonly detected (>85 %). PFOS, PFOA, PFHxS, PFHpS, and Me-PFOSA-AcOH decreased by up to 88 % during PFOA reduction-period (2006-2009) or elimination-period (2010-2016) compared to pre-policy (1999-2005), regardless of race/ethnicity; PFNA, PFUnA, PFDeA, PFDoA, and GenX increased by up to 104 % among non-White mothers. PFAS were up to 148 % higher in mothers who frequently consumed shellfish or fish or vegetables, worked, owned pet(s), or had wall-to-wall carpet, with stronger associations post-policy for shellfish, fish, and working. PFAS were up to 36 % lower in mothers who had cesarean-section, took vitamin supplements, or lived overseas during pregnancy, with weaker associations post-policy for delivery type and country of residence. CONCLUSION: Chemical policies can be effective at reducing PFAS exposures at the population-level, although the beneficial effects may not be equal across population-subgroups and could increase unregulated chemical exposures. Fish and vegetable consumption and occupational status were consistently associated with higher levels, while patterns of other predictors changed over time.
Environmental Research · 2025-09-04 · 2 citations
articleOpen accessUltraschall in der Medizin - European Journal of Ultrasound · 2025-10-01
articleEnvironment International · 2025-07-28 · 3 citations
articleOpen accessBACKGROUND: Some epidemiological studies suggest that phthalates adversely affect children's neurodevelopment, but results are inconsistent and often only consider individual chemicals. OBJECTIVES: We examined associations between gestational phthalate metabolites and intelligence at ages 3-4 and investigated effect modification by child sex. METHODS: We analyzed data from 511 mother-child pairs enrolled in the Maternal-Infant Research on Environmental Chemicals study. We measured specific gravity-standardized urinary concentrations of 20 phthalate metabolites (from nine parent compounds) in trimesters 1 and 2 and computed the average. We used linear regression models (log2-transformed), adjusting for covariates, to examine single-chemical associations with Full-Scale (FSIQ), Performance (PIQ), and Verbal IQ (VIQ) measured by the Weschler Preschool and Primary Scale of Intelligence-III. We estimated mixture effects using weighted quantile sum (WQS) regression. RESULTS: and VIQ and MMP and PIQ differed by child sex (negative for boys and positive for girls, respectively). WQS analyses were not statistically significant. CONCLUSIONS: is adversely associated with child cognition, with sex-specific vulnerabilities. The positive associations with MMP and MBzP warrant further research.
Environment International · 2025-12-06 · 1 citations
articleOpen accessBACKGROUND: Maternal serum concentrations of per- and polyfluoroalkyl substances (PFAS) during pregnancy have been consistently associated with reduced birthweight. However, these associations may be confounded by the timing of sample collection due to pregnancy-related changes in pharmacokinetics that impact both serum PFAS concentrations and birthweight. METHODS: We measured nine serum PFAS concentrations in each trimester among 728 women in the MABC Study (Ma'anshan, China, enrolled 2013-2014). We estimated covariate-adjusted differences in birthweight for individual PFAS and their mixture, as well as percent change in PFAS by infant birthweight. We repeated our analyses in 70 women-infant dyads from the HOME Study (Cincinnati, Ohio, enrolled 2003-2006) with repeated PFAS measures in 2nd trimester and at delivery. RESULTS: -transformed 1st and 3rd trimester PFOA was associated with a 6-gram (95 % CI:-35, 22) and 26-gram (95 % CI:-54, 3) decrease in birthweight, respectively. Concentrations of six PFAS declined more steeply among women who gave birth to larger vs. smaller infants. PFOA declined by 11.3 % (95 % CI:-12.7, -9.9) vs. 8.9 % (95 % CI:-10.3, -7.5) per 13 weeks among women who gave birth to infants born at the 90th vs. 10th birthweight percentiles, respectively. We observed similar findings in the HOME Study. CONCLUSIONS: These findings suggest that physiological changes in pregnancy may confound associations between serum PFAS and birthweight. Studies with PFAS measures later in pregnancy may overestimate the true effect of PFAS on fetal growth.
Environmental Research · 2025-11-12 · 1 citations
articleOpen accessBACKGROUND: Children are universally exposed to endocrine disrupting chemicals (EDCs) which may disrupt the vitamin D system through several mechanisms, including competitive receptor binding. Current epidemiologic evidence is limited, especially in children. We cross-sectionally investigated the short-term associations of 24 EDC biomarkers with 3 vitamin D biomarkers measured at ages 8 and 12 years. METHODS: Among 236 children from the Health Outcomes and Measures of the Environment Study, we quantified serum concentrations of 4 per-/poly-fluoroalkyl substances (PFAS), 5 polybrominated diphenyl ethers (PBDEs), and 3 vitamin D biomarkers and urinary metabolites of 4 organophosphate esters (OPE), 9 phthalates/replacements, and 2 environmental phenols at ages 8 (n = 180) and 12 (n = 187) years. Using linear regression models with generalized estimating equations, we estimated cross-sectional covariate-adjusted associations of interquartile range (IQR)-scaled log2 EDCs with vitamin D biomarkers. We used g-computation models to estimate effects of class-based and overall mixtures. RESULTS: A simultaneous IQR increase in all 24 EDCs was associated with 6.6 ng/mL (95% CI: 2.7, 10.6) higher total 25-dihydroxyvitamin D [total 25(OH)D]. Class-based mixtures of PFAS (β: 3.1; 95% CI: 1.3, 5.0), PBDEs (β: 2.1; 95% CI: 0.3, 3.9) and OPEs (β: 2.6; 95% CI: 0.3, 4.8) were associated with higher total 25(OH)D whereas environmental phenols (β: 0.8; 95% CI: -0.8, 2.4) and phthalates/replacements (β: -0.8; 95% CI: -3.3, 1.8) were not. Results for 24,25-dihydroxyvitamin D were similar. The PBDE mixture was associated with 4.0 pg/mL (95% CI: 0.4, 7.6) higher 1α,25-dihydroxyvitamin D. DISCUSSION: Findings suggest that EDCs may alter the childhood vitamin D system. Associations with higher vitamin D biomarker levels may indicate competitive receptor binding and altered cellular transport with potential adverse downstream health impacts.
Environmental Epidemiology · 2025-10-23
articleOpen accessBackground: Firearm-related lead exposure could occur when firearms discharge lead ammunition particles. Prior studies were primarily among military or police participants, but this relation has not been examined in civilian populations. Thus, among noninstitutionalized United States (US) adult civilians, we examined the association of self-reported firearm noise exposure (proxy for firearm-related lead exposure) and firearm use with blood lead concentrations. Methods: We used 5 cycles of the National Health and Nutrition Examination Survey. Using lead biomarkers and questionnaires related to firearm noise exposure (1999–2004, n = 9,606) and firearm use (2011–2012 and 2015–2016, n = 5,972), we calculated survey-weighted and covariate-adjusted percent differences in blood lead concentrations. We adjusted for gender, age, race/ethnicity, and education. Sensitivity analyses separately examined whether former military status, pre-1978 housing, or occupation confounded these associations. Results: Self-reported firearm noise exposure was associated with blood lead concentrations (percent difference 15%; 95% CI = 7%, 23%), but firearm use was not (percent difference 1%; 95% CI = −5%, 9%). However, blood lead concentrations were 9% (95% CI = −5%, 25%) and 21% (95% CI = −5%, 54%) higher among those who reported shooting 1,000–10,000 and 10,000+ rounds, respectively ( P value for trend = 0.07), compared with those who reported shooting 0 rounds. Results were similar after separate adjustment for former military status, pre-1978 housing, and occupation. Conclusion: In this representative sample of US civilians, individuals who used firearms more frequently (10,000+ rounds) had increased blood lead concentrations.
Recent grants
Maternal and Paternal Preconception Environmental Exposures and Children's Health
NIH · $3.0M · 2018–2024
Endocrine Disrupting Chemicals, Thyroid Hormones, and Child Neurobehavior
NIH · $1.8M · 2015–2020
Prenatal Sex Steroids, Bisphenol A, Phthalates, and Sexually Dimorphic Behaviors
NIH · $683k · 2013–2017
Early life perfluoroalkyl substance exposure & obesity: Mechanisms & phenotyping
NIH · $3.1M · 2016–2022
NIH · $84k · 2013
Frequent coauthors
- 661 shared
Bruce P. Lanphear
Child and Family Research Institute
- 641 shared
Kimberly Yolton
Cincinnati Children's Hospital Medical Center
- 410 shared
Antonia M. Calafat
Centers for Disease Control and Prevention
- 379 shared
Aimin Chen
University of Wisconsin–Madison
- 333 shared
Kim M. Cecil
Cincinnati Children's Hospital Medical Center
- 204 shared
Yingying Xu
Cincinnati Children's Hospital Medical Center
- 171 shared
George D. Papandonatos
Brown University
- 147 shared
Heidi J. Kalkwarf
Education
- 2010
PhD, Epidemiology
University of North Carolina at Chapel Hill
- 2008
MSPH, Epidemiology
University of North Carolina at Chapel Hill
- 2005
BS, Nursing
University of Wisconsin Milwaukee
- 2001
BS, Biochemistry
University of Wisconsin Madison
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