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

随着气候的变化，近年来发生了飓风和洪水等自然灾害，在这些受水破坏的环境中接触真菌对健康的潜在影响引起了公众的高度关注。为了评估暴露风险，开发改进的暴露评估方法对于识别在受水破坏的建筑和职业环境中导致个人暴露的真菌和相关次生代谢物至关重要。作为NIOSH健康危害评估和NIOSH及其外部合作者进行的其他实地研究的一部分，下一代测序方法已用于表征职业环境中存在的多种真菌。在FY22，我们完成了对宾夕法尼亚州费城50所小学500个教室的复杂真菌DNA测序数据的统计分析，并发表了详细研究的手稿。除了确定真菌群落特征和环境因素对群落组成的影响外，本研究还发现这些学校环境中存在高比例的子囊菌门和担子菌门酵母。此外，结果表明，在受水破坏最严重的教室中，彩曲霉的数量比受水破坏最轻的教室要多。微生物多样性对呼吸道感染的流行病学影响也在FY22进行了调查，结果表明，地板灰尘中的细菌多样性而非真菌多样性与学校工作人员呼吸道感染几率的降低显著相关。在FY22进行了额外的真菌DNA测序研究，以检查样品储存对确定真菌多样性能力的影响。重新提取费城学校研究中在-80°C保存了大约5年的灰尘样本（n=125），并对真菌ITS1区域进行测序。此外，从原始研究中提取的基因组DNA样本在-80°C下保存了4-5年，并对其进行了重新测序。本研究的数据分析目前正在进行中，将于23财年完成。高通量高效液相色谱-串联质谱（HPLC-MSMS）技术检测真菌次生代谢物是IAA的一部分。该方法可同时检测36种目标微生物次级代谢物，包括9种已知真菌毒素。针对室内粉尘样品较大的基质效应会严重影响二次代谢物定量的准确性，提出了一种调整方法来提高二次代谢物定量的准确性。来自美国不同地区（包括费城，宾夕法尼亚州，布里奇波特，康涅狄格州，威斯卡塞特，缅因州，哈特福德，康涅狄格州和佛蒙特州本宁顿）的多个室内办公室和学校建筑研究的地板灰尘样本的真菌DNA测序先前已完成，数据分析于22财年完成。对从不同类型的建筑物和地区收集的地板粉尘进行分析，将有助于深入了解从非住宅室内环境收集的地板粉尘中次生代谢物（包括霉菌毒素）的水平。

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.