Long-term exposure to ambient PM2.5 and its constituents is associated with MAFLD

Background & AimsExisting evidence suggests that long-term exposure to ambient fine particulate pollution (PM2.5) may increase metabolic dysfunction-associated fatty liver disease (MAFLD) risk. However, there is still limited evidence on the hepatotoxicity ranking of PM2.5 constituents associated with the MAFLD. Therefore, this study explores the associations between five main chemical constituents of PM2.5 and MAFLD to provide more explicit information on the liver exposome.MethodsA total of 76727 participants derived from the China Multi-Ethnic Cohort (CMEC), a large-scale epidemic survey in southwest China, were included in this study. Multiple linear regression models were used to estimate the pollutant-specific association with MAFLD. Weighted quantile sum regression was used to evaluate the joint effect of the pollutant-mixture effect on MAFLD and identify which constituents contribute most to it.ResultsThe 3-year exposure to PM2.5 constituents were associated with a higher MAFLD risk and more severe liver fibrosis. Odds ratios (ORs) for MAFLD were 1.480, 1.426, 1.294, 1.561, 1.618, and 1.368 per standard deviation increase in PM2.5, black carbon, organic matter, ammonium, sulfate, and nitrate, respectively. The joint exposure to the five major chemical constituents was also positively associated with MAFLD (OR: 1.490, 95% CI: 1.360–1.632). Nitrate contributed most to the joint effect of the pollutant-mixture. Further stratified analyses indicate that males, current smokers, and individuals with high-fat diet might be more susceptible to ambient PM2.5 exposure than others.ConclusionsLong-term exposure to PM2.5 and its five major chemical constituents may increase the risk of MAFLD. Nitrate might contribute most to MAFLD, which may provide new clues for liver health. Males, current smokers, and participants with high-fat diets were more susceptible to the above associations.