Wistar male rats, 3 months of age were given ad-libitum a nutritionally adequate diet and demineralized
drinking water. The
Molybdenum (Mo) and
Tungsten (W) were provided in the
drinking water at 200 ppm concentration. Intestinal
tumors were induced by
1,2-dimethylhydrazine (
DMH) given subcutaneously as 16 weekly doses at 20 mg/kg
body weight. Mo in the form of (NH4)6 Mo7O24 4H2O or W in the form of (Na2WO4) were provided in the
drinking water two months before the first
DMH treatment and were continued during 4 months more until the last
DMH treatment. Three months after the last
carcinogen injection, all animals were sacrificed and examined for intestinal
tumors. The number, size and location of the
tumors were recorded and the pathology was examined. The addition of Mo to the
drinking water induced an increase of hepatic Mo content. At the end of the second month, the hepatic content of Mo was 5.61 ppm, compared with control and W groups (2.18 and 0.96 ppm, respectively). A significantly lower incidence of
tumors was observed in the Mo group (47), compared with the control group given
DMH alone (105) and W group (113). On the other hand, the Mo group showed a significant decrease in the numbers of multiple
tumors per rat.