Occupational zirconium and co-metal exposure - cobalt, nickel, and arsenic: an integrated air and biomonitoring assessment in Taiwanese industry.

BACKGROUND: Zirconium (Zr) compounds have increasingly been used as alternatives to traditional toxic metals in industrial processes, yet comprehensive exposure and biomonitoring data are scarce. This study aimed to assess occupational exposure to zirconium and co-metals (cobalt, nickel, arsenic) in Taiwanese manufacturing industries through integrated environmental and biological monitoring. METHODS: A cross-sectional investigation was conducted in eight metal surface treatment plants, with biomonitoring conducted among ten exposed workers. Personal and area air sampling were analyzed for zirconium and co-metals using inductively coupled plasma-optical emission spectrometry (ICP-OES); urine and blood samples were analyzed for internal exposure biomarkers (urinary zirconium, urinary/blood cobalt, urinary nickel, blood arsenic) by inductively coupled plasma-mass spectrometry (ICP-MS). Pulmonary effects were assessed using spirometry. RESULTS: Airborne Zr concentrations varied substantially by process, with the highest levels observed in shelling and slurry mixing operations (up to 22.55 µg/m³). Urinary Zr was undetectable in all participants (< 0.2 µg/L), consistent with limited systemic absorption. In contrast, co-metals were consistently detected: cobalt and nickel were elevated in workers handling ceramic pigments and surface finishing tasks. Regression analyses indicated inverse associations between cobalt and hemoglobin, nickel and oxidative/inflammatory markers (8-OHdG, CRP), and positive associations between nickel and IgM, and arsenic and IgM. Spirometry indices remained within clinical reference ranges but tended to be lower among high-exposure workers. CONCLUSIONS: This study provides the first integrated dataset of zirconium and co-metal exposure in Taiwanese industry, showing measurable airborne Zr but undetectable urinary Zr under current conditions. Co-metals (cobalt, nickel, arsenic) demonstrated significant associations with hematologic, oxidative, and immunologic markers, underscoring the complexity of mixed-metal exposures. These findings support ongoing workplace surveillance and further research on health implications of zirconium and co-metal co-exposures.