Hepatocarcinogenicity of sterigmatocystin and versicolorin A to rainbow trout (Salmo gairdneri) embryos.

Versicolorin A (VA) and sterigmatocystin (ST) are biosynthetic precursors of aflatoxin B1 (AFB1). The carcinogenicity of these compounds relative to AFB1 was determined with the use of rainbow trout (Salmo gairdneri) embryo exposure. Exposure of 14-day rainbow trout embryos to a 0.5-ppm aqueous suspension of ST for 1 hour produced a 13% incidence of hepatocellular carcinomas among survivors 1 year later. Similar exposure of trout eggs to a 0.5-ppm solution of AFB1 produced a 53% incidence among survivors. Subsequent exposure of 21-day rainbow trout embryos to 5- and 25-ppm solutions of VA resulted in hepatocellular carcinoma incidences among survivors of 42 and 68%, respectively, at 12 months. A 0.5-ppm AFB1 positive control group had a 68% incidence among survivors of hepatocellular carcinomas at 1 year. These results established the carcinogenicity of VA for the first time and confirmed previous reports of ST carcinogenicity. Both compounds were of sufficient potencies to warrant caution as possible human health hazards.