Biomarkers of exposure to stainless steel tungsten inert gas welding fumes and the effect of exposure on exhaled breath condensate

The respiratory tract is the main target organ of the inhaled hexavalent chromium (Cr-VI) and nickel (Ni) contained in stainless steel (SS) welding fumes (WFs). The aim of this study was to investigate the Cr and Ni content of the exhaled breath condensate (EBC) of SS tungsten inert gas (TIG) welders, and relate their concentrations with oxidative stress and inflammatory biomarkers. EBC and urine from 100 SS TIG welders were collected pre-(T0) and post-shift (T1) on a Friday, and pre-shift (T2) on the following Monday morning. Both EBC and urinary Cr concentrations were higher at T1 (0.08 μg/L and 0.71 μg/g creatinine) and T0 (0.06 μg/L and 0.74 μg/g creatinine) than at T2 (below the limit of detection [LOD] and 0.59 μg/g creatinine), and EBC Ni concentrations generally remained <LOD. EBC hydrogen peroxide (H2O2) concentration increased from 0.18 μM at T0 to 0.25 μM at T1, but had decreased to 0.16 μM by T2. EBC malondialdehyde (MDA) concentrations were higher at T0 (2.79 nM) and T1 (2.98 nM) than at T2 (2.43 nM), and EBC 4-hydroxy-nonenal (HNE) concentrations were higher at T0 (0.53 nM) than at T2 (0.51 nM). These findings confirm that, unlike Ni-EBC, Cr-EBC is a reliable biomarker of exposure even at very low environmental concentrations. However, given the weak relationship between the biomarkers and effects of exposure, we speculate that other substances generated during SS TIG welding also play a role in generating lung oxidative stress.