Effects of cadmium on the mechanical strength of rat bones

Abstract

Wistar male rats (21 days-old at the start) were administered drinking water containing 0 (control), 1, 2.5 or 5ppm of cadmium respectively, for 25 weeks. All four groups were given a normal diet MF (ORIENTAL YEAST Co., LTD.). After the administration of cadmium, the femurs and the humeri were dissected out and used for mechanical strength tests. Ultimate strength, elasticity and fracture strain were measured under compressive, bending and torsional loadings. A hematological test, determination of Alp activity, NPN, BUN, calcium, phosphorus and iron levels in the serum, calcium, phosphorus and cadmium determinations in the tibia and cadmium determinations of the liver and kidney cortex were also done.There was no decrease in bone strength nor any anemia in the 1 and 2.5ppm groups.In the 5ppm group, the ultimate strength of the compressive, bending and torsional loadings decreased compared with the control group. There was a decrease in serum iron, but anemia was not observed. A slight decrease in serum Alp activity, NPN, BUN and calcium levels were also observed. The calcium and phosphorus levels in the tibia did not vary in the 5ppm group. Cadmium concentrations were 136.0±26.0ng/g dry weight of the epi- and meta-physes of tibia, 69.3±17.8ng/g dry weight of the diaphysis of tibia, 10.01±2.43μg/g dry weight of the liver and 30.23±4.52μg/g dry weight of the kidney cortex in the 5ppm group.