Dose-response analysis of cadmium in man: body burden vs kidney dysfunction

The primary objective of this study was to develop dose-response relationships of cadmium in human beings. In vivo measurements of kidney, liver, urine, and blood cadmium, and urinary levels of beta 2-microglobulin and total protein were obtained in 82 industrially exposed workers and 30 control subjects. The values of 200 micrograms/g creatinine for urinary beta 2-microglobulin and 250 mg/g creatinine for urinary total protein were used to define the upper limit for normal kidney function. Forty-one of the cadmium workers (18 active, 23 retired) were classified as having abnormal kidney function; all control subjects had normal kidney function. Most workers with Cd above 70 ppm in the liver were judged to have some evidence of kidney abnormalities. The dose-response relationship for liver cadmium for the actively employed workers could be described by a linear logistic regression model: (Formula: see text) where p is the individual's probability of having kidney dysfunction. The loss of cadmium from the kidney following dysfunction prohibited a direct logistic analysis of the kidney cadmium data. However, when the linear relationship between kidney and liver cadmium for the subjects with normal kidney function was combined with the logistic equation for the liver, a predicted-response curve was obtained for the kidney. The logistic models predict a 50% probability of having kidney dysfunction at 38.4 mg for the kidney and 42.3 ppm for the liver, respectively.