Increased risk of proximal tubular dysfunction due to occupational cadmium exposure: a survival analysis study.

Objectives: The objective of the current study was to elucidate the relationship between blood cadmium (Cd-B) levels and proximal tubular dysfunction using urinary β2-microglobulin (B2M-U) as an indicator among workers in nickel-cadmium battery plants in Japan.

Methods: Medical check-up data from 338 workers exposed to cadmium at 2 plants were collected from 1997 through 2020. Workers with at least 2 check-ups were included, excluding those with other renal dysfunctions. Proximal tubular dysfunction was defined as a B2M-U of 300 μg/g creatinine or higher in 2 or more consecutive check-ups. A multivariable Cox proportional-hazards regression model with time-dependent covariates was performed to analyze the relationship between Cd-B levels and the time to onset of proximal tubular dysfunction, adjusting for age, sex, and smoking history.

Results: Of the 338 workers, 238 met the study eligibility criteria for the analyses. The geometric mean of Cd-B was 1.97 μg/L. The Cox proportional hazards analysis demonstrated that higher time-dependent Cd-B levels were significantly associated with an increased risk of proximal tubular dysfunction, with a hazard ratio of 1.17 (95% CI: 1.06-1.29).

Conclusions: Higher Cd-B levels are associated with an increased risk of proximal tubular dysfunction in workers exposed to cadmium, indicating an increased risk of renal disease under the current industrial health management in Japan. Continuous monitoring and improved management of cadmium exposure are necessary to protect workers' health even in developed countries such as Japan.