Association of PM2.5 metal welding fume exposure with metabolite pathways.

aNumber of biochemical compounds within the same pathway;bNumber of biochemical compounds that have the same coefficient direction when regressed by exposure both in Study-2011 and Study-2012;cNumber of biochemical compounds with association p0.05 in combined dataset analyzed by linear mixed model with adjustment of age and medication use;dFirst principal component (PC1) was used as response, with PM2.5 total exposure as predictor in linear regression model or linear mixed-effects model;eProportion of variance explained by PC1;fPC1 was used as response in the linear mixed model with random slope with or without adjustment of age and medication use.