Urinary excretion of copper bound to low molecular weight proteins in the population exposed to cadmium in community and occupational environments.

People living in Cd-polluted areas excrete increased amounts of copper with urine. A substantial quantity of this is eliminated with metallothionein the concentration of which in urine increases in people exposed to cadmium. Therefore, the measurement of metallothionein in urine is applied as a marker of renal function in people exposed to cadmium in addition to other low molecular weight proteins, beta 2-microglobulins (beta 2MG) and retinol binding proteins (RBP). In this study copper bound to metallothionein-like proteins of low molecular weight (CuBP)--a newly proposed marker of cadmium nephrotoxicity, as well as beta 2MG and RBP, were evaluated in those exposed to cadmium in the community and in occupational environments. The results obtained indicated that people exposed to cadmium in both polluted environments excreted greater amount of CuBP in urine than people not exposed to cadmium. In groups excreting cadmium in urine in amounts ranging from 1 to 10 micrograms/l the urinary level of CuBP was closely associated with the levels of beta 2MG and RBP. A considerable increase in the excretion of urinary CuBP began when Cd concentration in urine exceeded 4 micrograms/l. The amount of CuBP excreted was higher in people with renal disfunction than in those with a normal renal function. It is suggested that urinary excretion of CuBP may be considered as a specific marker of renal function in people exposed to cadmium.