Bioavailability of arsenic in soil impacted by smelter activities following oral administration in rabbits.

This study determined the extent of arsenic (As) absorption from soil from Anaconda, Montana. Prepubescent male and female SPF New Zealand White rabbits (5/sex/group) were given a single oral (capsule) administration of soil (3900 ppm As) at three different dose levels (0.2, 0.5, and 1.0 g of soil/kg, corresponding to 0.78, 1.95, and 3.9 mg As/kg, respectively). Standard groups included untreated controls, an intravenous sodium arsenate group (1.95 mg As/kg), and a gavage sodium arsenate group (1.95 mg As/kg). Urine, cage rinse, and feces were collected at 24-hr intervals for 5 days and were analyzed for total As concentration. Clinical signs, body weights, and food consumption for treated animals were similar to controls. Maximum As concentrations were obtained over the initial 24-hr collection interval. A dose-dependent delay in urinary As excretion, the major elimination pathway, was observed in the oral soil group compared to that in the gavage group. For the animals in the soil groups, approximately 80% of the administered As dose was eliminated in the feces compared to approximately 10 and 50% for the intravenous and oral gavage groups, respectively. The relative oral bioavailabilities (+/- SD) of As in the gavage and test soil groups based on comparison with excreta data from the intravenous group were approximately 50 +/- 5.7 and 24 +/- 3.2%, respectively (after normalization of intravenous group's As recovery data to 100%). These results indicated that As in the soil was probably in a less soluble and therefore a less absorbable form than sodium arsenate.