Microplastic-associated gut microbial profile and antibiotic resistance in preschool children: a multicentre cross-sectional study in China

BACKGROUND: Microplastics (MPs) are ubiquitous in ecosystems and present in the human body, causing a worldwide environmental issue. However, the extent of human exposure to MPs remains largely unknown. Although mice exposed to MPs exhibit gut microbiota dysbiosis, the impact of MPs on the human intestinal microbiota remains unclear. Furthermore, MPs can carry and spread antibiotic resistance genes (ARGs). However, their potential influence on ARG abundance is underexplored. METHODS: A multicentre cross-sectional study was conducted in Xiamen, Shanghai, and Nanjing in China from October 2022 to March 2023. A total of 335 couples of faecal samples were collected and analysed for MPs using Py-GC/MS and gut microbiota using 16S rRNA and metagenomic sequencing. FINDINGS: Eight types of MPs were detected in 335 faecal samples, with a median concentration of 212.1 μg/g dw. MP exposure may be associated with the composition of the host gut microbiota. Microbial function analysis indicated the significant enrichment of 62 pathways primarily related to the metabolic pathways of macronutrients, vitamins, and bioactive substances. Total plastic concentration was significantly related to the relative abundance of species and ARGs, however this could not be attributed to specific plastic polymers after adjusting for covariates. INTERPRETATION: This study provides baseline data on the gap in understanding of preschoolers' MP exposure, supporting the hypothesis that MP exposure might disrupt gut bacterial constitution and functions. This raises concerns regarding the potential adverse effects on the human gut when exposed to MPs, particularly drug resistance risks in younger populations. FUNDING: Project of Shanghai Municipal Financial Professional foundation (Food Safety Risk Assessment) (grant number: RA-2023-10), National Natural Science Foundation of China (grant number: 2023YFF1104800), and Key Disciplines in the Three-year Plan of Shanghai Municipal Public Health System (2023-2025) (grant number: GWVI-11.1-42).