beta 2-Microglobulinuria among workers previously exposed to cadmium: follow-up and dose-response analyses

Sixty workers (58 males, 2 females) who had previously been exposed to cadmium in connection with the use of cadmium-containing solders were examined. Exposure times ranged from 4 to 24 years. For each worker a cumulative cadmium dose estimate was calculated. This ranged from 0.35 to 9.9 mg/m3 X year. The prevalence of slight (U-beta 2 greater than 0.034 mg/mmole creatinine) and more pronounced (U-beta 2 greater than 0.1 mg/mmole creatinine) beta 2-microglobulinuria in the whole group was 40% and 23%, respectively. The prevalence of beta 2-microglobulinuria was strongly related to the cumulative dose estimate and to urinary cadmium level. Among workers with a cumulative dose estimate below 1 mg/m3 X yr there were only a few cases with slight tubular proteinuria, whereas for workers who had a cumulative dose estimate exceeding 3 mg/m3 X yr the prevalence of slight and pronounced beta 2-microglobulinuria was 77% and 54%, respectively. There was no significant relationship between the concentration of beta 2-microglobulin in serum and urine. This indicates that the beta 2-microglobulinuria is due to tubular damage and is not secondary to an increased endogenous production. Repeated examinations of 19 workers between 1976 and 1983 revealed that in almost all cases the beta 2-microglobulinuria was irreversible.