Promoting activity of the herbicide dicamba (2-methoxy-3,6-dichlorobenzoicacid) in two stage hepatocarcinogenesis

Our goal was to examine whether dicamba, a widely-used broad leaf herbicide , has promoting activity in two-stage hepatocarcinogenesis. Female Sprague Dawley rats were given a single dose of diethylnitrosamine and then diets c ontaining dicamba, or phenobarbital, or both for six months. The number and volume of placental glutathione-S-transferase-positive, glucose-6-phosphat ase-negative or ATPase-negative foci were quantified in the liver. Dicamba alone did not increase the number or volume of these altered hepatic foci. Dicamba did, however, show a significant effect on the number or volume of certain markers in animals also treated with phenobarbital. These data show that dicamba in combination with other promoters may have weak promoting a ctivity in two-stage hepatocarcinogenesis in the rat.