Promotion of Aflatoxin-induced Hepatoma Growth in Trout by Methyl Malvalate and Sterculate

Young rainbow trout fed 20 ppb aflatoxin B1 for 1, 5, 10, 20, and 30 days developed 12-month hepatoma incidences of 3, 12, 10, 40, and 36%, respectively. Fish fed the same level of aflatoxin B1 in diets containing 100 ppm methyl sterculate for the same time periods developed 0, 17, 27, 74, and 85% incidences of hepatoma. Fish that had received 20 ppb aflatoxin B1 for 30 days were given either 0, 20, 50, or 100 ppm methyl sterculate for 9 months. Liver tumor incidences were 37, 65, 80, and 95%, respectively. The average volumes of tumor tissue per liver were 1, 52, 532, and 3450 cu mm for the corresponding diets. Methyl malvalate showed little tumor growth-promoting activity when fed in an identical manner at 50 ppm.