Urinary Chromium as an Indicator of the Exposure of Welders to Chromium

Five welders working with high alloy Cr-Ni steel and one working with mild steel were followed during one work week. The chromium concentration in air was measured concomitantly with urinary chromium determinations. The water-soluble chromium concentrations in air exceeded 0.05 mg/m³ during welding with coated electrodes, but metal inert-gas (MIG) welding produced much lower concentrations. The proportion of water-soluble hexavalent chromium in the air was usually more than 50 % of the total chromium concentration during welding with coated electrodes, whereas less than 10 % of the chromium produced during MIG welding was in a water-soluble form. Since water-soluble chromium (hexavalent) is the more important biologically, the determination of both water-soluble and waterinsoluble chromium concentrations is emphasized instead of the measurement of the total concentration. The urinary chromium concentration proved to be a good indicator of short-term exposure to water-soluble chromium when exposure was above the current threshold limit value of 0.05 mg/m³ , concentrations of more than 30 mg/g of creatinine representing an exposure level higher than the threshold limit value.