Determinants of occupational exposure to metals by gas metal arc welding and risk management measures: A biomonitoring study

•Our study evaluates Cr, Ni and Mn in urine as indicators of exposure to welding fumes by gas metal arc welding.•Concentrations of Cr/Ni/Mn in urine of welders are higher than unexposed subjects.•Urine levels are influenced by welding/grinding durations, age and welding experience, confinement and mechanical ventilation.•ICP-MS technique is suitable for assessing low exposures to metals in mild steel welders.•Biomonitoring protocol based on a spot-urine sample is adapted to small and medium sized enterprises.

Welding fumes contain various toxic metals including chromium (Cr), nickel (Ni) and manganese (Mn). An assessment of the risk to health of local and systemic exposure to welding fumes requires the assessment of both external and internal doses. The aims of this study were to test the relevance in small and medium sized enterprises of a biomonitoring strategy based on urine spot-samples, to characterize the factors influencing the internal doses of metals in gas metal arc welders and to recommend effective risk management measures. 137 welders were recruited and urinary levels of metals were measured by ICP-MS on post-shift samples collected at the end of the working week. Cr, Ni and Mn mean concentrations (respectively 0.43, 1.69 and 0.27 μg/g creatinine) were well below occupational health guidance values, but still higher than background levels observed in the general population, confirming the absorption of metals generated in welding fumes. Both welding parameters (nature of base metal, welding technique) and working conditions (confinement, welding and grinding durations, mechanical ventilation and welding experience) were predictive of occupational exposure. Our results confirm the interest of biomonitoring for assessing health risks and recommending risk management measures for welders.