Low level exposure to cadmium and early kidney damage: the OSCAR study

Objectives-To study the dose-response relation between cadmium dose and ren al tubular damage in a population of workers and people environmentally or occupationally exposed to low concentrations of cadmium. Methods-Early kidney damage in 1021 people, occupationally or environmental ly exposed to cadmium, was assessed from cadmium in urine to estimate dose, and protein HC (alpha(1)-microglobulin) in urine to assess tubular protein uria. Results-There was an age and sex adjusted correlation between cadmium in ur ine and urinary protein HC. The prevalence of tubular proteinuria ranged fr om 5% among unexposed people to 50% in the most exposed group. The correspo nding prevalence odds ratio was 6.0 (95% confidence interval (95% CI) 1.6 t o 22) for the highest exposure group, adjusted for age and sex. Multiple lo gistic regression analysis showed an increasing prevalence of tubular prote inuria with urinary cadmium as well as with age. After adjustment to the me an age of the study population (53 years), the results show an increased pr evalence of 10% tubular proteinuria (taking into account a background preva lence of 5%) at a urinary cadmium concentration of 1.0 nmol/mmol creatinine . Conclusion-Renal tubular damage due to exposure to cadmium develops at lowe r levels of cadmium body burden than previously anticipated.