Nature
Many moulds produce secondary metabolites (mycotoxins) that are highly toxic to humans and animals. The most infamous of them, the aflotoxins, affect some species at an intake of a few parts per billion. Each toxin has its own identity and pathology. Kidney and liver damage, haemorrhages, disturbances of the central nervous system, stunting of growth, abortion, or other effects may occur, depending on the toxin.