Effects of lifetime exposures to environmental contaminants on the adult gut microbiome. undefined

Emerging experimental evidence indicates that toxicant-induced alterations in gut microbiota composition and activity may affect host homeostasis. However, data from human studies are scarce; to our knowledge, no previous studies have quantified the association of lifetime exposure to environmental chemicals, across multiple time points, with the composition of the gut microbiome. Here we studied 125 individuals born in the Faroe Islands in 1986-1987 who were followed approximately every seven years from birth through age 28 years. Organochlorine compounds, including polychlorinated biphenyls (PCBs) and pesticides, perfluoroalkyl substances (PFAS), and mercury (Hg), were measured in cord blood and longitudinally in participants’ blood. At age 28, the gut microbiome was assessed using shotgun metagenomic sequencing. The relationship between the gut microbiome and environmental exposures was determined using permutational multivariate analysis of variance, feature-wise multivariate association with linear models, hierarchical all-against-all testing, and quantile g-computation (adjusting for important confounders). Historical contaminant exposures had little direct effect on the adult gut microbiome. This was also true for indirect measures such as total body burden, maximum exposure concentration, and exposure dynamics. While, a small number of fastidious anaerobes were weakly linked to recent PFAS/PFOS exposures at age 28. Our findings suggest no lasting effects of early-life exposures on adult gut microbial composition, but proximal exposures may contribute to gut microbiome alterations. The methods developed and used for this investigation may help in future identification of small but lasting impacts of environmental toxicant exposure on the gut microbiome.