Conceptual problems in establishing the critical concentration of cadmium in human kidney cortex

The definition of the "critical concentration" for cadmium is compared with the concepts used to establish this measure in some recent publications. The term has not been clearly defined on a population basis and this has given rise to certain confusion. Different groups of investigators therefore have arrived at different estimates of the "critical concentration" for cadmium in human kidney cortex. A new measure, the "population critical concentration" (PCC) with a clearly defined response rate, is suggested. A reanalysis of the published data indicates that the PCC-10 (10% response rate) for cadmium in kidney cortex is likely to be in the range 180-220 micrograms/g and the PCC-50 is likely to be about 25% higher.