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

TLDR

The study aimed to examine the dose‑response relationship between urinary cadmium exposure and renal tubular damage in workers and environmentally exposed individuals. The authors measured urinary cadmium to estimate exposure dose and urinary α‑1‑microglobulin to detect tubular proteinuria in 1,021 participants. Higher urinary cadmium was strongly associated with increased prevalence of tubular proteinuria, rising from 5 % in unexposed to 50 % in the highest exposure group, with an odds ratio of 6.0, and even a 1.0 nmol/mmol creatinine level linked to a 10 % excess prevalence, indicating that cadmium‑induced tubular damage occurs at lower body burdens than previously expected.

Abstract

OBJECTIVES To study the dose-response relation between cadmium dose and renal 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 environmentally exposed to cadmium, was assessed from cadmium in urine to estimate dose, and protein HC (α 1 -microglobulin) in urine to assess tubular proteinuria. RESULTS There was an age and sex adjusted correlation between cadmium in urine and urinary protein HC. The prevalence of tubular proteinuria ranged from 5% among unexposed people to 50% in the most exposed group. The corresponding prevalence odds ratio was 6.0 (95% confidence interval (95% CI) 1.6 to 22) for the highest exposure group, adjusted for age and sex. Multiple logistic regression analysis showed an increasing prevalence of tubular proteinuria with urinary cadmium as well as with age. After adjustment to the mean age of the study population (53 years), the results show an increased prevalence of 10% tubular proteinuria (taking into account a background prevalence of 5%) at a urinary cadmium concentration of 1.0 nmol/mmol creatinine. CONCLUSION Renal tubular damage due to exposure to cadmium develops at lower levels of cadmium body burden than previously anticipated.