Evaluation of sampling methods for toxicological testing of indoor air particulate matter

Abstract

There is a need for toxicity tests capable of recognizing indoor environments with compromised air quality, especially in the context of moisture damage. One of the key issues is sampling, which should both provide meaningful material for analyses and fulfill requirements imposed by practitioners using toxicity tests for health risk assessment. We aimed to evaluate different existing methods of sampling indoor particulate matter (PM) to develop a suitable sampling strategy for a toxicological assay. During three sampling campaigns in moisture-damaged and non-damaged school buildings, we evaluated one passive and three active sampling methods: the Settled Dust Box (SDB), the Button Aerosol Sampler, the Harvard Impactor and the National Institute for Occupational Safety and Health (NIOSH) Bioaerosol Cyclone Sampler. Mouse RAW264.7 macrophages were exposed to particle suspensions and cell metabolic activity (CMA), production of nitric oxide (NO) and tumor necrosis factor (TNFα) were determined after 24 h of exposure. The repeatability of the toxicological analyses was very good for all tested sampler types. Variability within the schools was found to be high especially between different classrooms in the moisture-damaged school. Passively collected settled dust and PM collected actively with the NIOSH Sampler (Stage 1) caused a clear response in exposed cells. The results suggested the higher relative immunotoxicological activity of dust from the moisture-damaged school. The NIOSH Sampler is a promising candidate for the collection of size-fractionated PM to be used in toxicity testing. The applicability of such sampling strategy in grading moisture damage severity in buildings needs to be developed further in a larger cohort of buildings.

The Toxicity of Wiped Dust and Airborne Microbes in Individual Classrooms Increase the Risk of Teachers’ Work-Related Symptoms: A Cross-Sectional Study

“…In toxicity measurements, various dust sampling and processing methods and different in vitro models have demonstrated contradictory results [16,[29][30][31][32]. The inflammatory potential of the deposited dust in human lung epithelial cell A549 assay was statistically significantly associated with employees' symptoms in schools [33] and offices [29].…”

Bioreactivity, Guttation and Agents Influencing Surface Tension of Water Emitted by Actively Growing Indoor Mould Isolates

“…Fungal pollution of indoor environment has been monitored by measuring fungal propagules in air, dust and building materials [50][51][52][53]. Monitored indicators have been the cultivable fungal conidia, evaluation of particles (conidia and hyphal fragments), presence of fungal DNA, or biomarkers as ergosterol, β-glucan, and specific mycotoxins [50,51,[53][54][55][56][57]. Cell toxicity assays were used to measure intrinsic toxicity in air and dust [50,57,58].…”

“…Monitored indicators have been the cultivable fungal conidia, evaluation of particles (conidia and hyphal fragments), presence of fungal DNA, or biomarkers as ergosterol, β-glucan, and specific mycotoxins [50,51,[53][54][55][56][57]. Cell toxicity assays were used to measure intrinsic toxicity in air and dust [50,57,58]. These methods used for monitoring microbial contamination of the indoor environment have drawbacks: Measuring cultivable conidia underestimates the fungal load, while DNA-based and microscopic methods as well as the measurement of fungal biomarkers do not distinguish the live from the dead [50,[52][53][54][55].…”

“…Each bio reactive metabolite exhibits an in vitro toxicity profile based on difference in sensitivity, i.e., a pattern of characteristic EC 50 concentrations obtained by the different in vitro toxicity assays. The characteristic toxicity profile indicated the biological target of the toxin as: intactness of the plasma membrane, ion fluxes and ion homeostasis [40,41,46], mitochondrial functions [40,61,66,67], transcription and translation [38,57]. The sperm motility inhibiting assay is sensitive to toxins affecting mitochondria and plasma membrane integrity, whereas the cell proliferation inhibition assays are sensitive to toxins affecting transcription and translation [40,41].…”

Cytotoxicity of Water Samples Condensed from Indoor Air: An Indicator of Poor Indoor Air Quality

“…Passive collection of settled dust and active collection of aerosolized particles are some of the choices to collect PM. [11][12][13][14][15] Dust and aerosols from spaces with poor indoor air quality have been shown to cause immunotoxicity in mouse RAW264.7 macrophages, 12,15 and to inhibit boar sperm motility. 11,13 Most recently, PM was shown to activate secretion of interleukin (IL)-8 and upregulate genes associated with immune response in a human in vitro airway construct.…”