AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Estimations of Oxidative Potential Contributed by Metal Oxides in Welding Fume Particles
JUN WANG, Jacob Bartels, Macrio Bezerra, University of Oklahoma Health Sciences Center
Abstract Number: 774 Working Group: Aerosol Exposure
Abstract Welding fume particles containing metal oxides contribute to oxidative potential (OP) and subsequently oxidative stress and other health outcomes. Welders are potential victims of significant fume exposure. The contributions from fume particles to OP are critical for understanding the health effects and risks of fume exposure. Anti-oxidant-based dithiothreitol (DTT) and ascorbic acid (AA) assays were widely used in estimating chemical-based OP of ambient particulates. However, the composition and concentration of welding fume particles differ vastly from ambient particulates. The concentrations of welding fume particles in workplaces are typically several magnitudes higher than ambient particulates, which may lead to a much faster reaction rate with the anti-oxidants. The composition of welding fume particles is predominantly metal oxides. In this study, a preliminary assessment of the applicability of DTT and AA assays to welding fume particles were conducted. Welding fume was generated in a fume chamber and collected with high volume flow pumps. The samples were extracted with buffer solutions and diluted to acceptable ranges for ultraviolet and visible spectrometer. The consumption of DTT and AA were measured as their reaction products 2-nitro-5-thiobenzoic acid and ascorbate at absorbances of 415 nm and 265 nm, respectively. Oxidation levels of welding fume were measured using a previously developed protocol based on metal cation concentration. General linear model was used to assess the correlation of DTT, AA, and metal cations. The results showed DTT assay performed poorly with welding fume particles and 78% of samples were unable to produce statistical significance. The AA consumption rate is between 0.68 and 1.27 nmol AA/min/μg of fume particles, which are substantially higher than the values reported in ambient particulate studies. The regression R value for AA with metal cations concentration is 0.67. Overall, AA assay performed superiorly than DTT assay with fewer steps involved.