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

随着气候的变化，最近发生了飓风和洪灾等自然灾害，这些水破坏环境中真菌暴露的潜在健康影响已引起公众的高度关注。为了评估暴露的风险，改进暴露评估方法的发展对于确定真菌和相关次生代谢物是至关重要的，这些真菌和相关次生代谢物有助于在受水破坏的建筑和职业环境中造成个人暴露。作为NIOSH健康危害评估和NIOSH及其外部合作者进行的其他现场研究的一部分，下一代测序方法已被用于表征职业环境中存在的各种真菌。在22财年，对从宾夕法尼亚州费城50所小学的500个教室收集的复杂真菌DNA测序数据进行了统计分析，并出版了详细介绍这项研究的手稿。除了真菌群落的特征和环境因素对群落组成的影响外，本研究还发现在这些学校环境中有较高比例的子囊菌和担子菌。此外，结果表明，与水损害最小的教室相比，水毁最严重的教室中有丰富的杂色曲霉。22财年还研究了微生物多样性对呼吸道感染的流行病学影响，结果表明，地板尘埃中的细菌多样性，而不是真菌多样性，与学校教职员工呼吸道感染几率的降低显著相关。在22财年进行了额外的真菌DNA测序研究，以检验样品存储对确定真菌多样性的能力的影响。来自费城学校研究的粉尘样本(n=125)在-80°C下储存了大约5年，被重新提取并对真菌ITS1区域进行了测序。此外，从原始研究中提取的相应基因组DNA样本在-80℃下保存了4-5年，并进行了重新测序。这项研究的数据分析目前正在进行中，将于2013财年完成。作为这项IAA的一部分，高通量高效液相色谱-串联质谱仪(HPLC-MSMS)技术已被开发用于检测真菌次生代谢物。该方法可以同时检测36种目标微生物次级代谢物，包括9种已知的霉菌毒素。针对室内粉尘样品的大基质效应会严重影响次级代谢物的准确定量的问题，提出了一种校正方法，以提高次级代谢物定量的准确性。此前，来自美国不同地区(包括宾夕法尼亚州费城、宾夕法尼亚州布里奇波特、康涅狄格州威斯卡塞特、密歇根州哈特福德和佛蒙特州本宁顿)的多个室内办公室和学校建筑的地板粉尘样本进行了真菌DNA测序，数据分析于22财年完成。从不同类型的建筑物和地区收集的地板粉尘的分析将提供对从非住宅室内环境收集的地板粉尘中次级代谢物，包括霉菌毒素的水平的洞察。

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.