Cadmium-induced bone loss: increased susceptibility in female beagles after ovariectomy.

Bone resorption, as measured by release of bone 45Ca, was significantly increased in elderly female beagles within 96 h of exposure to 15 mg/l cadmium in drinking-water. The 45Ca response was greater in ovariectomized animals than in sham-operated controls and was not mediated by changes in calciotropic hormone concentrations. Mean blood cadmium concentrations were 3-8 micrograms/l during the earliest bone resorption response and 13-15 micrograms/l at the end of the study. During seven months of cadmium exposure, bone mineral densities decreased most in the ovariectomized animals exposed to cadmium: -15.4 +/- 4.3% for the tibia distal end and -7.2 +/- 1.2% for the lumbar vertebrae (L2-L4) (mean +/- SE, n = 4). The results indicate that cadmium may act directly on bone and that postmenopausal women exposed to cadmium in industry or via cigarette smoke may be at increased risk of cadmium-induced bone loss. They also support a direct role of cadmium in the etiopathology of itai-itai disease among postmenopausal women in Japan.