P. species can be found at the sub-basement levels offices and rooms, in libraries, auditorium, storage room of paper materials and also in ventilation systems. Some P.species can produce small, nondescript conidia and complex mixtures of metabolites that are more or less toxic. Like all other molds, spores have the highest concentrations of mycotoxin, although the vegetative portion of the mold, the mycelium, can also contain the poison. Most naturally occurring Aspergilli are toxigenic or allergenic. Among several toxigenic species of this genus, the most important are, A. parasiticus, A. flavus, A. versicolor and A. fumigatus.
Aflatoxins are among the most extensively studied mycotoxin.
These are more toxic than many known industrial cancer causing substances, acutely toxic to the liver, brain, kidneys and heart, and with chronic exposure, are potent carcinogens of the liver. They are also teratogenic. Symptoms of acute aflatoxicosis are fever, vomiting, coma and convulsions. However, symptoms of exposure that might occur in most moderately contaminated buildings are not fully known, but undoubtedly less severe. The potent toxicity of these agents warrants prudent prevention of exposure when levels of aspergilli indoors exceed outdoor levels by any significant amount.