CONTAMINATED TREE NUTS peanuts, pistachios, brazil nuts, pecans, walnuts, almonds may contain aflatoxin a liver carcinogen derived from Aspergillus fungi. 120 countries have regulations for maximum allowable aflatoxin levels in food. Drought stress is one factor that ↑ Aspergillus aflatoxin contamination. The fungus is introduced in storage. Spices, peanut butter, chocolate, corn, seed oils, may contain aflatoxin.