Household triclosan and triclocarban exposure impacts the adult intestinal microbiome but not the infant intestinal microbiome

In 2016, the US Food and Drug Administration banned the use of specific microbicides in some household and personal wash products. This decision was due to concerns that these chemicals might induce antibiotic resistance or disrupt human microbial communities. Triclosan and triclocarban (referred to as TCs) are the most common antimicrobials in household and personal care products, but the extent to which TC exposure perturbs microbial communities in humans, particularly during infant development, was unknown. We conducted a randomized intervention of TC-containing household and personal care products during the first year following birth to characterize whether TC exposure from wash products perturbs microbial communities in mothers and their infants. Longitudinal survey of the intestinal microbiota using 16S ribosomal RNA amplicon sequencing showed that TC exposure from wash products did not induce global reconstruction of either infant or maternal intestinal microbiotas following 10 months of exposure after birth. However, broadly antibiotic-resistant species from the phylum Proteobacteria were enriched in stool samples from mothers in TC households only after the introduction of triclosan-containing toothpaste. Despite the minimal effects of TC exposure from wash products on the gut microbial community of infants and adults, these results suggest detected taxonomic differences are associated with potential harmful effects on host physiology, highlighting the need for consumer safety testing of self-care products not subject to the ban on the human microbiome and health outcomes.