Zirconium, niobium, antimony, vanadium and lead in rats: life term studies
Schroeder, HA; Mitchener, M; Nason, AP
To evaluate innate effects of the trace elements zirconium, niobium, antimony and vanadium, and to reevaluate those of lead, 603 rats of the Long-Evans strain were fed a diet containing relatively small amounts of these elements in an environment reasonably free of trace contaminants. Groups of 100 or more divided as to sex were given 5 ppm (as metal) either zirconium, niobate, antimonite, or vanadyl ions, and 25 ppm lead (males only) in drinking water from the time of weaning until natural death, and compared with an equal number of controls. Chromium 1 ppm was in the water. These doses were tolerable for growth which was enhanced in the male niobium group. Innate toxicity in terms of life span and longevity occurred in the antimony groups. In rats given antimony, nonfasting serum glucose levels were lower than fasting, an unusual finding. Increased incidences of glycosuria occurred in the zirconium, niobium and lead groups. Serum cholesterol was abnormal in the antimony and vanadium groups. Antimony and lead accumulated in soft tissues, the former with age. No element was tumorigenic. Lead-fed males lost weight from 24 to 30 months of age and their coats were poor, the only signs of toxicity. A previous series of chromium-deficient rats given the same dose of lead showed early mortality, shortened life span and decreased longevity. Chromium may be antagonistic to lead toxicity.