REPRODUCIBILITY OF URINARY BETA(2)-MICROGLOBULIN AND CADMIUM EXCRETION AMONG RESIDENTS IN A CADMIUM-POLLUTED AREA DURING A 3-YEAR PERIOD

To assess the measurement error by using single exposure measurement i n epidemiologic studies, reproducibility of urinary beta(2)-microglobu lin and cadmium excretion was evaluated among persons exposed to envir onmental cadmium. We measured urinary beta(2)-microglobulin concentrat ions in 47 subjects four times and urinary cadmium concentrations in 4 8 subjects twice, during a 3-year period. Between-person and within-pe rson variance components of these variables were estimated using a ran dom-effects one-way analysis of variance model. The intraclass correla tion coefficient (ICC) for urinary beta(2)-microglobulin concentration , when expressed as mu g/g creatinine and mu g/l, was 0.92 and 0.89, r espectively. The ICC for standardized urinary cadmium concentration (e xpressed as mu g/g creatinine) was 0.81, while it decreased to 0.33 wi thout standardization. The findings suggest that single measurement of urinary beta(2)-microglobulin and cadmium, when expressed as a functi on of creatinine, can reliably estimate average levels over at least a 3-year period. Standardization of concentration using urinary creatin ine improved reproducibility especially for urinary cadmium excretion. (C) 1997 Elsevier Science Ireland Ltd.