The Effects of Thirdhand Smoke Exposure on the Microbiome of Young Children. Thirdhand Smoke and The Microbiomes

We present results from the first study to examine the effects of thirdhand smoke (THS) on the environmental (EMB) and human microbiome (HMB). Specifically, we investigated if homes of smokers who smoked only outdoors differed in their indoor EMB and child’s HMB compared to nonsmoker homes. Participants were n=19 THS exposed children (≤ 2 years) and n=10 children of never smokers who were not exposed to secondhand smoke. Personal interviews were conducted with parents, and samples of house dust and surface wipes were collected and analyzed for THS pollutants. Environmental (floor, table, armrest, bedframe) and biological samples (infants’ hand, nose, mouth, and ear canal) were analyzed using high-throughput DNA sequencing. Child hand wipe and urine samples were analyzed for THS exposure. Findings showed phylogenetic α-diversity significantly higher for the EMB in THS homes compared to nonsmoker homes (p0.25), they differed in the composition of their microbial communities, specifically: Neisseria (nose, ear, finger), Corynebacterium (ear, nose, finger), Streptococcus (mouth, finger), Staphylococcus (nose, ear, finger), and Moraxella (mouth, ear, finger). Findings from this study provide strong foundation for future studies that focus on the effects of THS on the diversity and composition of the EMB and HMB and their role in pediatric clinical outcomes.