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Facts About Mold AIHA® December 2011 10 Stachybotrys: Genus that includes approximately 10 species and occurs mainly on dead plant materials. Of these, Stachybotrys chartarum and its sister species S. chlorohalonata are the most common. These species are widespread and typically grow on straw. In the indoor environment, Stachybotrys is commonly found on cellulosic materials, including paper, canvas, and jute, that are wetted to a water activity > 0.98. This is a toxigenic mold. There are two chemotypes of this species that produce trichothecenes plus spirolactones or atranones plus spirolactones; these toxins have been demonstrated on mold‐damaged building materials. The closely related species Memnoniella echinata occurs on the same materials but does not produce potent trichothecenes. Both chemotypes of S. chartarum/S. chorohalonata and M. echinata typically occur together on samples of very wet cellulosic materials with M. echinata being more important in warmer climates. This fungus does not cause invasive disease. Allergens of S. chartarum sensu latto have been identified. "Toxic mold": This has no scientific meaning, since mold itself is not toxic. The metabolic byproducts of some molds may be toxic (see Mycotoxins). Toxigenic fungi: Fungi that can produce mycotoxins (see Mycotoxins). Common Indoor Fungi Alternaria: A genus comprised of approximately 50 species, most of which are saprophytes or plant pathogens. Alternaria alternata is an extremely common saprophyte found worldwide on plants, wood, wood pulp, textiles, and food. A. alternata grows on the surfaces of leaves (phylloplane) and occurs in outdoor air at modest levels, peaking in July or August depending on the location (reaching perhaps 500 spores/m 3 ). The allergens of A. alternata can induce reactions at very low concentrations in sensitized individuals. Phylloplane strains of A. alternata that are found in air do not produce AAL toxin. Some produce the phytotoxin (a compound toxic to plants) alternariol and related metabolites. Aspergillus: The asexual stage of a number of Ascomycetes. Species of Aspergillus are distributed worldwide, although they are more common in warmer climates. These species grow on a vast array of organic materials. There are 182 accepted species, although only 40 occur with any frequency. Species of Aspergillus include several of considerable economic importance: A. flavus is the main producer of the potent carcinogen aflatoxin and A. fumigatus is an important cause of the invasive disease aspergillosis. Several species are common on building materials, including A. versicolor. A. fumigatus is common in outdoor air in some regions during the fall, occurring on composting materials. Cladosporium: A genus comprised of approximately 500 species, most of which are saprophytes or plant pathogens; perhaps 20 are common. Cladosporium sphaerospermum, C. cladosporoioides, and C. herbarum are the most common species. All are found on plants, wood, wood pulp, textiles, and food. Of the three, C. sphaerospermum is the species typically found on building materials. The other two are phylloplane species that occur in outdoor air at high levels, peaking in June, July, or August depending on the location (reaching perhaps 10,000 spores/m 3 ). C. herbarum produces a wide variety of allergens, and approximately 10 percent of the population is sensitized to Cladosporium. Phylloplane strains of Cladosporium do not produce metabolites with material toxicity. Penicillium: The asexual stage of a number of Ascomycetes. The species of Penicillium are found worldwide but are more common in temperate climates. These species grow on a vast array of organic materials. There are 225 accepted species, although only 70 occur with any frequency. Species of Penicillium include several of considerable economic importance: P. verrucosum produces ochratoxin on cereals and P. chrysogenum

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