Urine metabolomics analysis of construction painters with complex chemical exposures

Construction painters involved in metal structure coating experience complex chemical exposures, including epoxy resins, amine cross-linkers, isocyanates, organic solvents and flame retardants. These exposures induce oxidative stress and downstream metabolic perturbations, yet integrative metabolomic evidence in this workforce remains scarce. This study aimed to characterize urinary metabolomic alterations associated with distinct construction-related exposure scenarios including painting workers applying epoxy-based mid-coat and isocyanate-based top-coat. Untargeted urinary metabolomics was performed using liquid chromatography mass spectrometry (LC-MS) in pre- and post-shift samples collected from professional construction painting workers. Daily exposure effects were assessed using pre- versus post-shift urinary metabolomic comparisons, while exposure biomarker-associated metabolomic alterations were evaluated using tertile exposure stratification based on established urinary exposure biomarkers. The association of metabolic responses related to heat stress/dehydration was assessed using urinary specific gravity values. Statistical analyses included Student's t-testing, pathway enrichment analysis, and correlation analysis. Solvent-related metabolites, including hippuric and methylhippuric acids, were markedly elevated among coating workers. Both exposure groups showed significant alteration of amino acid metabolism and glutathione metabolism. In addition, mid-coat workers showed exposure effects on vitamin B6 metabolism, riboflavin metabolism, and catecholamine biosynthesis specifically. Top-coat workers demonstrated the exposure effects of nicotinate and nicotinamide metabolism. These findings demonstrate that distinct coating-related exposures mixtures could yield unique metabolic signatures, despite complex mixtures exposures with overlapping chemical signatures.