Urinary excretion of proteins among metal welders

Joining of metals by welding confer an exposure of dust particulates containing several toxic substances. Chromium, nickel and manganese is absorbed in the lungs and may adversely affect the renal function. We compared biological markers of glomerular filtration (Kampmann clearance) and tubular function (post-shift urine spot sample concentration of respectively albumin, immunoglobulin G, transferrin, orosomucoid and beta 2-microglobulin) among 102 ever-welders and 33 never-welders (mostly electricians). The welders were subdivided into groups of stainless steel welders (n = 35), mild steel welders (n = 46) and ex-welders (n = 21). Each group was separately referenced with never-welders. The Kampmann clearance was within normal limits in all workers and not related to welding exposure. However, the urinary concentration of the majority of proteins was 1.5 to 3.0 times higher in both stainless steel and mild steel welders. The number of welding years taken as a measure of cumulative welding exposure was not related to levels of proteins in urine when adjusting for the effect of age. In addition, no alteration of urinary proteins was found among the ex-welders apart from slightly elevated albumin. This indicates that the apparent effect of welding on renal tubular function may at least partially be reversible. In conclusion, this study is in support of the hypothesis that metal welding may adversely affect renal tubular function, but it is questionable whether welding exposure has bearings as to occurrence of clinical significant kidney disease.