Air exposure assessment and biological monitoring of manganese and other major welding fume components in welders
In a cross-sectional study, 96 welders were compared with 96 control subjects. Also 27 former welders, all diagnosed as having manganism, were examined. Exposure to welding fumes was determined in the 96 welders, while the concentration of elements in whole blood and urine was determined in all subjects. The geometric mean (GM) concentrations of manganese (Mn) and iron in the workroom air were 97 μg m−3 (range 3–4620 μg m−3; n = 188) and 894 μg m−3 (range 106–20 300 μg m−3; n = 188), respectively. Thus the Mn concentration in the workroom air was on average 10.6% (GM) of that of the Fe concentration. No substantial difference was observed in the air Mn concentrations when welding mild steel as compared to welding stainless steel. The arithmetic mean (AM) concentration of Mn in whole blood (B-Mn) was about 25% higher in the welders compared to the controls (8.6 vs. 6.9 μg l−1; p < 0.001), while the difference in the urinary Mn concentrations did not attain statistical significance. A Pearson’s correlation coefficient of 0.31 (p < 0.01) was calculated between B-Mn and Mn in the workroom air that was collected the day before blood sampling. Although the exposure to welding fumes in the patients had ceased on average 5.8 years prior to the study (range 4 years–7 years), their AM B-Mn concentration was still higher than in referents of similar age (8.7 μg l−1vs. 7.0 μg l−1). However, their urinary concentrations of cobolt, iron and Mn were all statistically significantly lower.