| Abstract: | Liver cancer in rainbow trout was induced by exposure of fertile eggs to an aqueous, 0.5 ppm (microgram/ml) solution of aflatoxin B1 (AFB1) for 1 hour. Single treatments, given on alternate days during the embryonic period, produced a low cancer incidence (less than 20%) prior to formation of the embryonic liver on day 14, but a steadily increasing incidence from day 15 (31.7%) until day 23 (58.3%), in fish examined 1 year later. Treatment of trout eggs with 14C]AFB1 was used to quantitate the amount of AFB1 absorbed by the eggs. Twenty-one-day-old rainbow trout eggs absorbed approximately 30 ng of 14C]AFB1 during a 1-hour exposure to 0.5 ppm aqueous 14C]AFB1. After 1 day 85-90% of the 14C]AFB1 was either metabolized and excreted or leached from the egg. The residual 14C]AFB1 remained constant until hatching when an additional 50% was lost. Comparison of the amount of AFB1 absorbed by eggs with the amount of AFB1 consumed per fish during a 1-year feeding trial at 4 ppb in the diet indicates that the trout embryo is even more sensitive than juvenile trout to the carcinogenic properties of AFB1. |
