Life Term Studies on the Effects of Arsenic, Germanium, Tin, and Vanadium on Spontaneous Tumors in Mice1

Mice fed a diet low in many trace elements and raised in an environment where contamination from extraneous trace ele ments was controlled were given small amounts (5 jig/ml) of arsenite, germanate, stannous, or vanadyl ions in drinking water for their life times. Animals receiving arsenite had a significantly decreased incidence of all tumors, and of tumors of the lung, compared to those receiving tin, vanadium, and to controls. Fewer spontaneous tumors were also found in animals given germanium. Significant differences in the incidences of malig nant tumors did not appear. None of the elements was carcino genic in the doses given.