Biomonitoring of metal oxide nanoparticles in stainless steel welders

Introduction: Welding can cause worker exposure to metal oxide nanoparticles (MO-NPs), including Cr2O3, Mn3O4 and NiO NPs. Our aim was to assess MO-NP exposure in welders through biological monitoring. Materials and Methods: Welders (n. 18), from 2 Italian welding companies, provided exhaled breath condensate (EBC) and urine samples at the beginning and at the end of the shift on the 1st and 5th day of the workweek, and plasma samples at this latter time-point. Unexposed controls (n. 15) provided only one sample for each biological matrix. Single Particle Mass Spectrometry (SP-ICP-MS) technique was used to assess MO-NPs exposure in terms of particle concentration (p/mL) and size (nm). Results: In welder EBC, Cr2O3 NPs showed a significantly higher median concentration at the post-shift of the 5th day of the week (64645 p/mL; 55.1 nm) compared to the pre-shift of the 1st day (15836 p/mL; 57.7 nm). The median Cr2O3 NP plasma concentration and size were significantly lower than in EBC (7762 p/mL; 44.3 nm), while no Cr2O3 NPs were determined in urine. Welders from one of the two companies showed NiO NPs in EBC of the 5th day (median 22000 p/mL; 64.8 nm) and plasma (8248 p/mL; 37.4 nm), although not in EBC of the 1st day and in urine. Cr2O3 and NiO NPs were not determined in controls. Mn3O4 NPs were not detected in any samples of welders and controls. Conclusions: Although promising, the usefulness of EBC biomarkers of MO-NP exposure needs confirmation on a greater number of workers, under different quantitative and qualitative exposure conditions in order to inform risk assessment and management in welding operation