[Relation between environmental concentration, urinary elimination and body burden of chromium in occupationally exposed workers].

Biological and environmental monitoring of chromium exposure was carried out on 20 welders working with special electrodes in the manufacture of tank-cars. The workers were divided in groups, according to the different degree of chromium accumulation, which was determined by renal clearance of diffusible chromium. A closed linear relationship between TWA concentration of hydrosoluble chromium in air and urinary excretion of the metal at the end of exposure was observed. The parameters of regression lines in welders with more (clearance 10 ml/min) or less (clearance 5 ml/min) accumulation of chromium suggest that the renal burden influences not only the basal excretion, but also the excretion at the end of exposure. We underline the difficulty in the determination of correct biological limits if we take them from TLV in air. We must at least consider the degree of accumulation in exposed workers too.