Abstract
In the indoor environment, people are exposed to several fungal species. Evident dampness is associated with increased respiratory symptoms. To examine the immune responses associated with fungal exposure, mice are often exposed to a single species grown on an agar medium. The aim of this study was to develop an inhalation exposure system to be able to examine responses in mice exposed to mixed fungal species aerosolized from fungus-infested building materials. Indoor airborne fungi were sampled and cultivated on gypsum boards. Aerosols were characterized and compared with aerosols in homes. Aerosols containing 107 CFU of fungi/m3 air were generated repeatedly from fungus-infested gypsum boards in a mouse exposure chamber. Aerosols contained Aspergillus nidulans, Aspergillus niger, Aspergillus ustus, Aspergillus versicolor, Chaetomium globosum, Cladosporium herbarum, Penicillium brevicompactum, Penicillium camemberti, Penicillium chrysogenum, Penicillium commune, Penicillium glabrum, Penicillium olsonii, Penicillium rugulosum, Stachybotrys chartarum, and Wallemia sebi. They were all among the most abundant airborne species identified in 28 homes. Nine species from gypsum boards and 11 species in the homes are associated with water damage. Most fungi were present as single spores, but chains and clusters of different species and fragments were also present. The variation in exposure level during the 60 min of aerosol generation was similar to the variation measured in homes. Through aerosolization of fungi from the indoor environment, cultured on gypsum boards, it was possible to generate realistic aerosols in terms of species composition, concentration, and particle sizes. The inhalation-exposure system can be used to study responses to indoor fungi associated with water damage and the importance of fungal species composition.
Highlights
Areview paper concluded that evident dampness or mold in buildings has been associated with multiple allergic and respiratory health effects; measured microbial agents in dust have limited suggestive associations [1]
Different numbers of fungal spores can be aerosolized per fungus-infested area from different species [10, 19], and the relative humidity (RH) affects the number of spores aerosolized as a response to exposure to an airflow [7, 8, 20]
In studies of the health effects of fungal exposure, using mice as model organisms, fungi are typically grown on agar media and in cultures of only one fungal species, and fungal spores are often washed before exposure (Table 1)
Summary
Areview paper concluded that evident dampness or mold in buildings has been associated with multiple allergic and respiratory health effects; measured microbial agents in dust have limited suggestive associations [1] This might be due partly to the multitude of existing microbial species and to the fact that other changes occur concurrently with water damage development. Building constructions are expected to be exposed to several species simultaneously, and studies have revealed several fungal genera on indoor surfaces [17] and in settled dust [18]; less is known at the species level and for airborne fungi. In studies of the health effects of fungal exposure, using mice as model organisms, fungi are typically grown on agar media and in cultures of only one fungal species, and fungal spores are often washed before exposure (Table 1).
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