Lead levels in tissues from rats fed soils containing lead.

Abstract

Laboratory rats were fed soils containing elevated concentrations of lead. One soil was taken adjacent to a heavily traveled highway and one near a house that had been painted for many years with lead pigment paints. In addition, a third group of rats was fed lead acetate at a level in the diet similar to that in the diet of the rats fed soil. A fourth group of rats was fed a typical diet containing a normal amount of lead. Blood, bone, liver, kidney, and brain were analyzed for lead after 30 and 90 days of feeding. There was no statistically significant difference in blood lead levels between any of the groups. Similarly, brain and liver tissues showed no elevation in lead concentration compared to the controls except for the animals fed lead acetate that showed a slight elevation in lead in liver tissue at 30 days. Kidney tissue was elevated about 3- to 4-fold compared to controls, the rats fed lead acetate responding somewhat more than the rats fed soil lead. Bone tissue was elevated 3- to 5-fold compared to controls and at 90 days the rats fed lead acetate had higher bone lead levels than the rats fed soil. These results are compared to similar feeding studies reported in the literature. The greater response of tissue to lead in the earlier studies is thought to be due to a low bulk diet. The ALAD activity was measured in the blood of the rats. At 30 days the ALAD was not statistically lower than the controls, but at 90 days the rats fed lead were inhibited by approximately 20% compared to controls. Neither the lead-containing soil nor the lead acetate had an effect on the animal body weight gain or on the weight of liver, kidney, or brain. The retention of lead in bone and other tissues was very similar in the three dietary lead groups. The results of this feeding study indicate that these animals metabolize and handle the lead in different soils and from different sources in a very similar manner.