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

National Institute Of Environmental Health Sciences

Investigators

Abstract

Consensus reports have identified associations between exposure to damp indoor environments, microbial growth, and adverse respiratory health effects. Inhalation exposure of fungal bioaerosols found within these damp contaminated environments continues to be an area of great public concern especially for residents residing in or returning to these water damaged environments following natural disasters or flooding events. To assess the risk of exposure, the development of standard exposure assessment methods to identify and quantify microbial bioaerosols is critical, in order to determine sources, metabolic byproducts and biomarkers of exposure. Building upon the research conducted in previous years, NIOSH continued ongoing projects in FY21 to better understand the adverse health effects caused by fungal exposure. In FY21, additional work was conducted in the efforts to develop a high-throughput high performance liquid chromatography ? tandem mass spectrometry (HPLC-MSMS) method to detect fungal secondary metabolites. Fungal DNA sequences from 500 dust samples previously collected from 50 elementary schools were examined in FY21. Fusarium graminearum and F. culmorum were identified and produced the mycotoxin, deoxynivalenol, from 48.1% and 83.4% of the samples, respectively. Evaluation of the dust samples collected from the classrooms of 50 schools resulted in the identification of 11.8 million fungal DNA sequences that contributed to the characterization of the fungal diversity present in elementary classrooms. In this study, more than 1,182 fungal species were identified from 500 classrooms and almost 20% of fungal DNA sequences were classified as yeasts or yeast-like fungi. These findings demonstrated the contribution of yeasts within school environments and a manuscript presenting these results is in preparation. Associations between the presence of yeast or certain yeast taxa and respiratory illnesses in teachers will be examined in future studies. Additional epidemiologic analyses examining the associations of exposure to secondary metabolites with respiratory and non-respiratory health problems in staff of the 50 elementary schools will also be conducted. Previous sequencing-based studies conducted at NIOSH have also identified fungal yeasts, which are often overlooked, as sources of personal exposure. Basidiomycota yeasts are prominent in indoor contaminated environments, but their role in adverse health effects has remained relatively uncharacterized. To address this knowledge gap, species-specific primers, probes, and a quantitative polymerase chain reaction (qPCR) method were developed to provide for the first time, the detection and quantification of Vishniacozyma victoriae (syn. Cryptococcus victoriae). This species-specific qPCR assay was used in a collaborative study to detect and quantify V. victoriae in dust samples from homes participating in the New York City Neighborhood Asthma and Allergy Study (NAAS). The influence of housing factors and health effects associated with V. victoriae exposure in homes of children from low and high asthma prevalence neighborhoods in the New York metropolitan area were examined. The results from these studies, which were published in 2021, provide new insight into the association between fungal yeast exposure and airway diseases.