Biomarkers of iron status and trace elements in welders

Iron status was studied in 137 welders exposed to a geometric mean (GM) air concentration of 214 μg/m3 (range 1-3230) of manganese (Mn), in 137 referents and in 34 former welders. The GM concentrations of S-ferritin were 119 (3-1498), 112 (9-1277) and 98 (12-989) μg/L (p = 0.24) in the three groups, respectively. Also the GM concentrations of S-hepcidin were not significantly different between the groups (8.4 μg/L (2.8-117); 6.6 μg/L (1.8-100); 6.5 μg/L (1.2-22)) (p = 0.22). Multiple linear regression analysis including all welders and referents showed an increase in the concentration of S-ferritin associated with having serum carbohydrate deficient transferrin (S-CDT) above the upper reference limit of ≥1.7%, indicating high alcohol consumption. Serum C-reactive protein was not associated with exposure as welders, but an association with S-ferritin was shown. The GM S-ferritin concentrations among all welders and referents with S-CDT ≥ 1.7% were 157 μg/L (95% CI 113-218) as compared to 104 μg/L (95% CI 94-116) (p = 0.02) in those with S-CDT < 1.7%. The GM concentrations of Mn in biological fluids were higher in the welders as compared to the referents, while S-Fe, S-Co and B-Co were statistically significantly lower. This could suggest a competitive inhibition from Mn on the uptake of Fe and Co. Increasing concentrations of S-CDT was associated with higher S-Mn, S-Fe and B-Co in the multiple linear regression analysis. The association between S-CDT and S-Fe remained when all subjects with high S-CDT (≥1.7%) were excluded, suggesting increased uptake of Fe even at lower alcohol consumption.