Low-level chronic exposure to cadmium enhances the risk of long bone fractures: a study on a female rat model of human lifetime exposure.

In the present paper, the hypothesis that low chronic exposure to cadmium (Cd) enhances the risk of long bone fractures was investigated in a female rat model simulating human lifetime exposure in non-Cd-polluted areas. For this purpose, the femur and both tibias of control female rats and those exposed to Cd (1 mg Cd I(-1) in drinking water for 24 months since weaning) were assigned to geometric, densitometric (bone mineral content, BMC, and density, BMD), radiographic and biomechanical studies as well as assessing their chemical composition. The exposure to Cd disturbed mineralization (decreased BMD and minerals content, including calcium, magnesium, zinc, copper and iron) and weakened the biomechanical strength of the femur and tibia, enhancing their fragility. The Z-score values for the BMD revealed osteopenia of the femur and tibia in 20 and 30% of the Cd-exposed female rats, respectively, and osteoporosis in 80 and 70%, respectively. In 30% of the Cd-exposed animals, femoral neck fracture was evident in the radiographic picture. The findings seem to confirm the hypothesis that a low exposure to Cd during the lifetime may be an important risk factor for osteoporosis and fractures of long bones, and especially for femoral neck fracture in elderly women. The results indicate that greater attention should be paid to Cd as an environmental risk factor for the increasing rate of osteoporosis and bone fractures in old population.