Adequate dietary calcium mitigates osteopenia induced by chronic lead exposure in adult rats

The purpose of the present study was to investigate bone changes in the adu lt rat exposed to low lead levels during intake of normal dietary calcium a nd to contrast these findings with data from our earlier studies performed with animals receiving low dietary calcium concurrent with lead exposure. T he present study exposed adult rats to 100 ppm lead via drinking water for 12 weeks and assessed bone histology, 1,25-dihydroxyvitamin D, 25(OH)vitami n D and parathyroid hormone levels. No osteopenia was evident by quantitati ve bone histology, and circulating levels of 1,25-dihydroxyvitamin D, 25(OH ) vitamin D and parathyroid hormone were normal. Bone ash findings document ed incorporation of significant amounts of lead into bone mineral. These fi ndings document absence of interference with vitamin D metabolism, absence of secondary hyperparathyroidism and absence of osteopenia following 12 wee ks of low lead exposure in the adult rat maintained on normal calcium intak e. Results stress the importance of adequate calcium intake in our elderly population who may be exposed to cumulative, low-level lead exposure.