Naturally occurring toxic substances in foods

Numerous chemical toxins, including normal components of natural foods, e.g., mycotoxins, and toxic chemicals as contaminants such as pesticides, fertilizers, food additives, and preservatives, which are potentially toxic to humans, are discussed. Potential toxiciiy, the hazard to man represented by most of these chemicals, may be low because the concentration in food may be low. The gap in our knowledge of long‐term effects makes rational decisions as to allowable levels of these substances a major problem. On the other hand, nitrosamines and afiatoxins are toxins for which there exists a voluminous literature documenting extreme biologic activity in experimental animals and indirect evidence for activity in man. Epidemiologic evidence has linked them to human cancers, and because of increasing evidence of long‐term human exposure to these toxins either as inadvertent contaminants during food preparation or as the metabolites of mycotic infestation this possible hazard demands intensive investigation. An exhaustive review of data from epidemiologic surveys in various parts of the world, as well as from long‐term laboratory studies, represents an impressive start in this direction.