Four groups of 10 male, albino Sprague Dawley rats receiving either deionized water or deionized water containing 300 parts per million (ppm) F as NaF, 200 Pb as Pb acetate or F+Pb at 300 and 200 ppm, respectively, as drinking water for 10 weeks were fed a casein-based purified diet. Pb alone produced no mortality but increased blood, kidney, and femur Pb concentrations, produced a slight reduction in body weight gain, development of intranuclear inclusion bodies in the kidney and a slight anemia. F alone produced a small but consistent reduction in body weight but no mortality. The combination of Pb+F produced 30% mortality in this group and a severe loss of body weight in 2 surviving animals. F produced significantly higher Pb concentrations in blood and femur but not kidney of rats receiving either deionized water or 200 ppm Pb. F did not affect hemoglobin, hematocrit, or free erythrocyte protoporphyrin levels but reduced the urinary excretion of delta aminolevulinic acid in both control and Pb-treated rats. Intranuclear inclusion bodies and cloudy swelling associated with swollen proximal tubule cell mitochondria were observed in the Pb and Pb+F groups. The combination of Pb and F was much more severely toxic than either compound alone. The mechanism by which this increase in toxicity occurs is not apparent from the current experiment. It is not likely that the mortality and weight loss of animals receiving Pb+F may be explained on the basis of increased Pb retention.
Institutional Affiliations of Authors:
K.R. Mahaffey and C.L. Stone: Food and Drug Administration (FDA)
B.A. Fowler: National Institute of Health (NIH)