Associations of Urinary Triclosan Concentrations Across Gestation and Childhood with the Adolescent Gut Microbiome.

Research on the influence of repeated exposure to antimicrobial chemicals, such as triclosan, on the microbiome is lacking. The goal of this study was to elucidate the associations of time-varying urinary triclosan concentrations with the adolescent gut microbiome. We used data from a prospective cohort based in Cincinnati, OH (enrolled 2003-2006, n = 146), to assess the time-varying associations of urinary triclosan concentrations with adolescent (age ∼ 12 years) gut microbiome diversity and composition. Individuals ≥ 18-years-old were recruited during the second trimester of pregnancy, and urinary triclosan concentrations were measured in pregnant women up to 2 times in pregnancy and up to 7 times in the child from ages 1 through 12 years. At age ∼ 12 years, fecal microbiome diversity and composition was characterized with metagenomic sequencing. We estimated differences in the relative abundance of prevalent (≥50%) bacterial species and gene pathways using linear regression and generalized estimating equations to assess windows of heightened susceptibility adjusted for sociodemographic characteristics. Additionally, we examined sex-specific associations by including an interaction term. The adolescent median Shannon diversity was 3.5 (IQR: 3.3, 3.5). Higher gestational triclosan concentrations with lower gut microbiome diversity [β = -0.13 per 10-fold increase (95%CI: -0.24, -0.02)]. Triclosan concentrations were also positively associated with higher abundance of antibiotic resistance genes and differential abundance of some bacterial species, with the strongest associations observed in early life and at age 12 years. We also found differences depending on sex, with more significant associations observed among males. Our findings provide insight into windows of triclosan exposure that are relevant to gut microbiome composition and the impacts of antimicrobial agents.