The impact of school heavy metal exposure on children's gut microbiota: The mediating role of environmental microorganisms.

Heavy metals are toxic and harmful pollutants that can affect the school environment and the exposed children's health. This study collected dust samples and children's fecal specimens, and performed gene sequencing. We used eXtreme Gradient Boosting to determine the impact of heavy metals on environmental microorganisms and gut microbiota, while using the relative length of the quadrant and Fourth-corner analysis to explore the relationship among the three components. We found heavy metal pollution existed in the classroom environment, with lead and copper significantly affecting environmental microorganisms' community structure. Although nonsignificant associations were observed between heavy metals and gut microbiota, Fourth-corner analysis revealed the associations were significantly mediated by environmental microorganisms. Both heavy metals and microorganisms in the environment can disrupt the microbial community structure in the intestines of exposed children.