Change of urinary cadmium and renal tubular damage markers of 8 occupationally exposed-cadmium workers: A 6-year follow-up after exposure ceasing

Objective To understand the change characteristics of urinary cadmium and renal tubular damage effect markers of workers occupationally exposed to high level cadmium after they stopped the exposure.

Methods Eight occupationally exposed-cadmium workers with high urinary cadmium level were followed-up for 6 years after they stopped occupational exposure to cadmium. The urinary cadmium, 2 micro-globulin and retinol-binding protein levels were examined annually from 2009 to 2014. The urinary KIM-1 was detected by ELISA in 2014 and the results were compared with the references.

Results After the workers stopped occupational exposure, urinary cadmium varied and there was a trend that it decreased gradually, though the difference in each year was not statistically significant (P>0.05);the urine β₂-MG and the urinary retinol binding protein were in the normal range. After the exposure ceasing for six years, the urine tubular injury molecule -1 (KIM-1) level of exposed-cadmium workers was(1.37 ±0.61)ng/mL, which was significantly higher than that of the reference persons(P < 0.05).

Conclusion After exposure ceasing for six years, the urinary cadmium was still high, while urinary β₂-MG and urinary retinol-binding protein levels, the traditional markers of renal tubular damage, were not significantly changed. However, the increased urinary KIM-1 indicated that the renal tubular damage of these workers still existed after the exposure ceasing for six years.