Urinary metabolomics as a window into occupational exposure: the case of foundry workers

Foundries represent complex exposure scenarios where metals, particulate matter, and combustion by-products coexist, posing potential cumulative biological effects. Urinary metabolic profiles from 64 foundry workers and 78 residents living in surrounding areas were investigated using multivariate statistical modeling. Differences in urinary metabolite patterns were observed between the two groups, including lower levels of several amino acids (e.g., valine, alanine, tyrosine, and tryptophan) and tricarboxylic acid intermediates (e.g., citrate and succinate), together with higher levels of selected branched-chain amino acid catabolites (e.g., 3-hydroxyisobutyrate and erythro-2,3-dihydroxybutyrate) in workers. Variations in gut microbiota-related metabolites, such as phenylacetylglycine and p-cresol sulphate, were also detected. Based on these metabolic patterns, potential molecular mechanisms related to energy metabolism, oxidative stress and host–microbiome interaction are discussed as interpretative hypotheses. The comparison between workers and residents was interpreted, taking into account differences in demographic and lifestyle characteristics between groups. Overall, the results indicate that occupational exposure in foundries is associated with measurable differences in urinary metabolic profiles, demonstrating that the applied NMR-based metabolomic strategy is capable of capturing early biological effects and supporting its potential as a non-invasive and holistic biomonitoring tool for evaluating the health impact of complex occupational exposures.