TOXICOKINETICS OF CADMIUM IN LACTATING AND NONLACTATING EWES AFTER ORAL AND INTRAVENOUS ADMINISTRATION

We studied the toxicokinetics of cadmium on two groups of ewes, a lact ating group and a nonlactating group, after single intravenous and ora l administrations of cadmium chloride using a semisimultaneous method and a three-compartment model. The nonlactating ewes showed a low cadm ium bioavailability (0.12-0.22%), a large steady-state volume of distr ibution (23.8 +/- 5.4 liter/kg), and a low blood clearance (0.20 +/- 0 .03 liter/kg/day). Their mean residence time was 113 +/- 28 days. The lactating ewes had a higher bioavailability (0.33-1.7%). Their mean re sidence time was close to that in nonlactating ewes despite a greater blood clearance (0.46 +/- 0.013 liter/kg/day) because the volume of di stribution of cadmium in the body was larger (V-SS = 48.8 +/- 10.3 lit er/kg). Their cadmium clearance in milk, changing with time, remained low and could not explain their higher blood clearance. In one nonlact ating ewe, a greater cadmium bioavailability (5%) increased cadmium in the body. Increased cadmium amounts could induce renal damage and sho rten the mean residence time (78 days). (C) 1997 Academic Press.