Inhibitory effects of molybdenum on esophageal and forestomach carcinogenesis in rats

Male weanling inbred SD rats were given ad libitum a nutritionally adequate semipurified diet and demineralized drinking water without or with 100 or 200 ppm tungsten (W) or 2 or 20 ppm molybdenum (Mo) added to the drinking water. The animals were gastrically intubated with a solution of N-nitrososarcosine ethyl ester (NSEE) from the 4th week twice weekly for 2-8 consecutive weeks. The addition of Mo at either the 2- or 20-ppm level significantly inhibited NSEE-induced esophageal and forestomach carcinogenesis. The 200 ppm W significantly countered the inhibitory effect of a low level of Mo naturally occurring in the diet.