Specifically, "A. penicillioides" predigests dandruff, destructs fats and keratin, which are the main components of mites' food. The fungus also contributes its spores, vitamins B and D for "D. pteronyssinus". Conversely, "A. penicillioides" has adverse effects on "D. pteronyssinus". The ratio between mite and fungi in a given concentration of substrate is important in determining growth dynamics of mites in culture. When there are abundant substrates available, fungus captures substrates quicker than mites due to their shorter life cycle and greater reproductive potential. This leads to the slow development of mites and higher mortality. "A. penicillioides" can also alter the physical nature of substratum, which impedes mites' movement and increases food handling time. Female mites are more susceptible to these deleterious effects because they need to invest energy for egg production. "Aspergillus penicillioides" is known as a causal agent of foxing on paper art work and books. It was once isolated from the brown spots on ancient Egyptian painting in Tutankhamun's tomb. Some mechanisms for discoloration include colored pigments secreted by mycelia, maillard reaction, and enzyme production that causes chemical change in the paper. Prevention treatment with pentachlorophenol failed to inhibit development of fungus. "Aspergillus penicillioides" also caused mildew in cotton goods in Great Britain. In contrast, it was rarely found from deteriorated fabrics. This inconsistency may be due to differences in isolation techniques. Cigar culture molded with an "Aspergillus" was described to show gray green color. Appearance and measurements corresponded to "A. penicillioides". Careful studies suggested that these cigar molds consisted mainly of "A. penicillioides"-like form. "Aspergillus penicillioides" is a common indoor fungus in damp buildings where it has been associated with allergic rhinitis. Under high level of exposure to indoor fungus, an association was found between fungal concentration and development of allergic rhinitis. Despite that this species was originally described from a skin infection, the principle human exposure hazard is likely to be through the inhalation route. Products of mold growth, such as volatile organic metabolites and spores, may contribute to discomfort such as allergy and asthma. Sustained growth of house dust mites by "A. penicillioides" can also be a health hazard.