Sterigmatocystin (SMC) is a mycotoxin with a very similar structure to AFB1. Sterigmatocystin is produced by more than 50 types of fungus, including the Aspergillus fungus species. Sterigmatocystin has been found in samples of nuts, beer and grains including wheat, barley, rye, oat and rice, as well as Grain products including flour, bread and pastries, pasta, cereal and muesli.