Estimation of benchmark doses for urinary cadmium based on β2-microglobulin excretion in cadmium-polluted regions of the Kakehashi River basin, Japan

A benchmark dose low (BMDL) is used as a replacement for the no observed adverse effect level. The threshold levels of urinary cadmium (Cd) as BMDL were estimated using data from the Kakehashi River basin. The target population (>= 50 years) comprised 3178 and 294 participants inhabiting Cd-polluted and non-polluted areas, respectively. Cut-off values for beta(2)-MG-uria were defined as the 84 and 95% upper limit values calculated from control subjects, and 1000 mu g/l or mg/g cr of beta(2)-MG. Using these cutoff values, the BMDL at which the excess risk is 0.05 was determined to be 2.9-4.0 mg/g cr (males) and 1.5-3.6 mg/g cr (females). The present study demonstrated that a BMD approach is useful to estimate the threshold level of urinary Cd in Cd-exposed subjects and people living in general environment without any known Cd-pollution since a BMD approach does not need abnormality rates of urinary findings in the controls.