LINKING POLYCYCLIC AROMATIC HYDROCARBON EXPOSURE, THE GUT MICROBIOME, AND IMPULSIVITY IN A HUMAN COHORT

Polycyclic aromatic hydrocarbons (PAHs) are pervasive environmental pollutants linked to adverse neurobehavioral outcomes, yet the biological pathways that couple exposure to behavior are poorly defined. We investigated whether the human gut microbiome relates PAH exposure to impulsivity in a statewide adult cohort. Participants completed validated impulsivity assessments, provided fecal samples for 16S rRNA profiling, and contributed personalized passive measures of PAH exposure. Higher PAH exposure associated with greater impulsivity and with shifts in gut community structure; impulsivity also associated with increased microbial alpha-diversity and with differences in unweighted UniFrac distances. The PAH-impulsivity relationship was moderated by sex, with the largest exposure elevations observed among highly impulsive males. At the taxon level, several genera correlated with specific PAHs, including Methanobrevibacter, Paraprevotella, Roseburia, Ruminococcaceae genera, and Erysipelatoclostridium, microbes previously implicated in xenobiotic metabolism or production of neuroactive metabolites. Together, these results reveal a triad linking PAH exposure, gut microbiome composition, and impulsivity, suggest sex-dependent biology, and highlight putative bacteria-dependent detoxification and signaling pathways that merit mechanistic investigation. This study identifies microbiome features that could inform risk stratification or interventions aimed at reducing the neurobehavioral burden of ubiquitous PAH exposures.