Exposure Assessment of Indoor and Occupational Aerosols

National Institute Of Environmental Health Sciences

Investigators

Abstract

The potential health effects associated with fungal exposure in water-damaged environments has become a greater concern for the public due to recent hurricanes and flooding events as well as dampness encountered in the built environment. 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 fungal diversity present in occupational environments as part of NIOSH health hazard evaluations and other field studies conducted by NIOSH and external collaborators. In FY23, statistical analyses were conducted for a study in which 50 public elementary schools in Philadelphia, PA which examined the association between exposure and respiratory infections of school staff, and the results will be submitted for publication in FY24. Additional analyses on relationships between individual taxa and yeasts with the health outcomes are ongoing. Secondary microbial metabolites collected in floor dust samples as part of the Philadelphia school studies are also being evaluated and associations between exposures to these secondary metabolites and respiratory illnesses will be assessed. Fungal DNA sequencing studies were conducted in FY23 to examine the effect of storage of samples and extracts on the stability of fungal DNA. A high-throughput high performance liquid chromatography – tandem mass spectrometry (HPLC-MSMS) technique to detect fungal secondary metabolites has been developed allowing for the simultaneous detection of 36 targeted microbial secondary metabolites including nine known mycotoxins. An adjustment method was developed to decrease the previously observed large matrix effects of indoor dust, which significantly hindered accurate secondary metabolite quantification. A manuscript detailing the method was published in in FY23. This method was used to evaluate microbial secondary metabolites in floor dust samples from both non-flooded homes and homes flooded by Hurricane Harvey. In these studies, 14 metabolites including three mycotoxins were identified with low prevalence and were found to be significantly influenced by the location and the damage status of homes. Indoor temperature and relative humidity also negatively affected the concentration of some metabolites.