Studies of Nutritional Safety of Some Heavy Metals in Mice

Heavy metals have been proposed as nutrient markers to allow the accurate determinations of the time of passage, nutrient intake, or apparent utilization of multiple nutrients. In order to evaluate possible toxic effects of scandium, chromium, lanthanum, samarium, europium, dysprosium, terbium, thulium, and ytterbium oxides, and barium sulfate upon growth, general development, reproduction, and lactation, mice were fed different levels of these compounds for three generations. The amounts of elements fed were 0, 1, 10, 100, and 1,000 times the use amount. The use amounts were (in ppm): Sc, 0.12; Cr, 0.02; La, 0.40; Sm, 0.80; Eu, 0.036; Tb, 1.20; Dy, 1.20; Tm, 0.08; Yb, 0.12; and Ba, 0.008. The use amount was one-fifth of the concentration required for activation analysis. Mortality and morbidity were negligible. No consistent growth rate changes were observed; however, different groups showed different growth rates during different generations. The number of mice born showed no significant differences among treatment groups. Survival, growth rate, hematology, morphological development, maturation, reproduction, and lactational performance were comparable in mice fed the different levels of 10 heavy metal oxides to those mice fed the basal diet.