Zinc and copper levels in ribs of cadmium-exposed persons with special reference to osteomalacia.

Cadmium (Cd), zinc (Zn), copper (Cu), calcium (Ca), phosphorus (P), and magnesium (Mg) were determined in ribs obtained at autopsy from 38 Cd-exposed and 17 nonexposed subjects to determine how levels of these elements in bone are affected by Cd exposure and whether they are associated with the bone lesions due to Cd exposure, osteomalacia, and osteoporosis. Cd in ribs was significantly higher in the Cd-exposed subjects than in nonexposed subjects. Zn tended to be higher, while Cu, Ca, P, and Mg tended to be lower in the ribs of Cd-exposed subjects, though these differences were not statistically significant. Zn, Ca, P, and Mg were highly correlated with each other in both Cd-exposed and nonexposed groups, but the associations of Ca, P, and Mg in the ribs with Zn concentrations differed in subjects and controls. Ca to Zn ratios were low in the Cd-exposed subjects, and the higher the grade of osteomalacia, the lower the Ca/Zn ratio. The decrease in Ca/Zn ratio was significantly correlated with increases in Cd. Cu showed a significant positive correlation with Cd and significant inverse correlation with Ca, P, and Mg in the Cd-exposed group. Cu and its relation to other elements did not show any association with osteomalacia. In conclusion, Ca/Zn ratio in bone was related to Cd exposure and the degree of osteomalacia in the Cd-exposed subjects.