Abstract
We investigated the biological half-life of the urinary cadmium concentration (U-Cd) based on a 24-year
follow-up study after cessation of cadmium exposure in a cadmium-polluted area. Spot urine samples
were obtained from all inhabitants in this area in 1979, 1986, 1991, 1999 and 2003. Biological half-life was
calculated in the inhabitants whose U-Cd was more than 5 μg l−1 (9 men and 12 women) or 5 μg g−1 creatinine
(9 men and 19 women) using a one-compartment model. The estimated half-life and 95% condence
intervals were 13.6 years (9.0–28.2 years) and 13.9 years (9.6–25.6 years) for unadjusted U-Cd in men and
women, respectively. For creatinine-adjusted U-Cd, they were 14.2 years (11.2–19.4 years) and 23.5 years
(17.7–35.0 years) in men and women, respectively. The biological half-lives of U-Cd obtained in this study
were identical with the values of total body burden determined by a dierent method.