The short-term in vivo expression of precarcinogenicity of potassium bromate (KBrO3), a food additive, was examined. KBrO3 was orally administered singly or in combination with benzo-[a] pyrene (B [a] P) or B [a] P alone, in male of 6 week-old SPF-ddy mice. KBrO3 was given in the drinking water for two weeks at concentration of 5000, 2500, 1000, 500 or 100 ppm. KBrO3-B [a] P simultaneous administration groups were given in the corn oil solution of B [a] P at 100 mg/kg, once a week for two weeks. The results obtained were as follows : 1. The body weight gains were inhibited by KBrO3 of a high concentration (5000 ppm). But, after the administration the organ weights of the liver, lung and kidney showed no difference among groups administered with KBrO3. 2. As for tumor makers, α-fetoprotein (AFP), alkaline phosphatase (EC 3.1.3.1, ALP) and γ-glutamyl transpeptidase (EC 2.3.2.2, γ-GTP) activities in the plasma were determined. The results of this experiment demonstrated that the AFP values increased in KBrO3 groups and KBrO3-B [a] P simultaneous groups, 2-3 fold that of the control group given distilled water alone. AFP value and ALP activitiy increased independently of the dosage of KBrO3. Moreover, the γ-GTP activities more significantly increased in all experimental groups than that of the control, and also showed the same results additively by simultaneous administration of KBrO3 and B [a] P. However, the γ-GTP activities in the liver were not remarkably enhanced in all experimental groups. These results suggested that formation of oxygen radicals in the target organs such as the liver, kidney and lung was closely related to KBrO3 precarcinogenesis.
