Assessment of Inhalation Exposures to Indoor and Occupational Aerosols - Exposure Assessment of Indoor and Occupational Aerosols

National Institute Of Environmental Health Sciences

Investigators

Abstract

With the changing of climates, recent natural disasters have occurred such as hurricanes and flooding events and the potential health effects of fungal exposure in these water-damaged environments has heightened public concern. To assess the risk of exposure, the development of improved exposure assessment methods is critical to identify fungi and associated secondary metabolites that contribute to personal exposure within water-damaged built and occupational environments. Next-generation sequencing methods have been used to characterize the diverse array of fungi present in occupational environments as part of NIOSH health hazard evaluations and other field studies conducted by NIOSH and its external collaborators. In FY22, the statistical analyses of complex fungal DNA sequencing data collected from 500 classrooms in 50 elementary schools in Philadelphia, PA was completed and the manuscript detailing the study was published. In addition to characterizing the fungal community and the effects of environmental factors on community composition, this study also identified a high proportion of Ascomycota and Basidiomycota yeasts in these school environments. Furthermore, results showed that Aspergillus versicolor was abundant in the most water-damaged classrooms compared to the least water-damaged classrooms. The epidemiological effect of microbial diversity on respiratory infection was also examined in FY22 and results indicated that the bacterial diversity, but not fungal diversity, in floor dust was significantly associated with decreased odds of respiratory infection in school staff. Additional fungal DNA sequencing studies were conducted in FY22 to examine the effect of sample storage on the ability to determine fungal diversity. Dust samples (n=125) from the Philadelphia School study that had been stored at -80°C for approximately 5 years were re-extracted and the fungal ITS1 region was sequenced. Additionally, the corresponding extracted genomic DNA samples from the original study, which had been stored at -80°C for 4-5 years, were re-sequenced. Data analysis for this study is currently ongoing and will be completed in FY23. High-throughput high performance liquid chromatography – tandem mass spectrometry (HPLC-MSMS) techniques to detect fungal secondary metabolites has been developed as part of this IAA. This method allows the simultaneous detection of 36 targeted microbial secondary metabolites including nine known mycotoxins. As large matrix effects of indoor dust samples can significantly hinder accurate secondary metabolite quantification, an adjustment method was developed to improve the accuracy in secondary metabolite quantification. Fungal DNA sequencing of floor dust samples derived from multiple indoor office and school building studies in different regions in the US, including Philadelphia, PA, Bridgeport, CT, Wiscasset, ME, Hartford, CT and Bennington, VT, was performed previously, and the data analyses was completed in FY22. The analyses of floor dust collected from different types of buildings and regions will provide insight into the levels of secondary metabolites, including mycotoxins, in floor dust collected from non-residential indoor environments.