Electrostatic Dust Collectors (EDCs) are a passive sampling method that has not yet been fully validated. Our first study investigated the effect of EDC mailing and EDC deployment in front of and away from heated ventilation on endotoxin concentrations. Endotoxin sampling efficiency of heated and unheated EDC cloths was evaluated. EDCs express mailed cross-country yielded no significant changes in endotoxin concentrations when dust-only samples were compared to high quality control (QC) spiked-EDCs (p=0.21) and low QC spiked-EDCs (p=0.16). EDCs were deployed in 20 apartments with one EDC placed in front of the univent heater and another EDC placed on a built-in bookshelf. Endotoxin concentrations were significantly different (p=0.049) indicating that EDC placement impacts endotoxin sampling. Heated and unheated EDCs were deployed for 7 days in farm homes. There was a significant difference between endotoxin concentrations (p=0.027). The electrostatic charge of 12 heated and 12 unheated EDC cloths were significantly different (p=0.009). These studies suggest that heating cloths may diminish their electrostatic charge and endotoxin sampling capabilities.
The EDC sampling time needed to achieve detectable and reproducible loading for bioaerosols has not been systematically evaluated. In our second study, EDCs were deployed in 15 Iowa farm homes for 7-, 14-, and 28-day sampling periods to determine if endotoxin and allergens could be quantified and if loading rates were uniform (i.e. doubling from 7 to 14 days and 14 to 28 days and quadrupling from 7 to 28 days). Loadings between left and right paired EDC cloths were not significantly different and were highly correlated for endotoxin, total protein, and cat (Fel d1), dog (Can f1) and mouse (Mus m1) allergens (p<0.001). EDC endotoxin sampling had close agreement between paired samples (Pearson p=0.96, p<0.001). EDC endotoxin loading doubled from 7 to 14-day deployments but the loading rate decreased from 14 to 28 days of sampling with only a 1.38 fold increase. Allergen exposure assessment using EDCs was less satisfactory.
Paired EDCs and daily Button aerosol samplers (BS) were used in our third study to concurrently sample endotoxin in 10 farm homes during 7 day periods in summer and winter. Winter sampling included an optical particle counter (OPC) for particulate size and number concentration data. OPC particulate matter (PM) data were divided into PM2.5 and PM10-2.5. Summer sampling yielded geometric mean and geometric standard deviation values of 0.82 EU/m3 (2.7) for inhalable aerosol BS and 737 EU/m2 (1.9) for EDCs. Winter values were 0.52 EU/m3 (3.1) for BS and 538 EU/m2 (3.0) for EDCs. Seven day endotoxin values of EDCs were significantly and highly correlated with the 7-day BS sampling averages (p=0.70; p<0.001). An Analysis of Variance indicated a 2.37-fold increase in EDC endotoxin concentrations for each unit increase of the ratio of PM2.5 to PM10-2.5. A 10-fold increase in BS endotoxin concentrations was associated with a 12.2-fold increase in EDC endotoxin concentrations.
Our fourth study established QC protocols use of EDCs in large field studies. QCs were developed for endotoxin, peptidoglycan, and glucan for analysis alongside the Agricultural Lung Health study EDC samples. The coefficient of variation percentage (CV) for each QC was used to determine variability. For each QC, 20 EDC cloths were analyzed to establish an acceptable range (mean ± 3 standard deviations). Two QCs were established for endotoxin analysis. The high QCs were dust-spiked EDCs with a CV of 29.7%. The low QCs were spiked with E. coli standard and had a CV of 15.6%. One QC was established for peptidoglycan analysis using dust-spiked EDC extracts. Two glucan QCs were established using dust-spiked EDCs with a high CV (51.7%) and yeast-spiked EDCs with a CV of 26.0%. Endotoxin and glucan concentrations of AGLH EDC samples were found to be significantly correlated (p=0.71; p<0.0001). In conclusion, EDCs are an effective passive sampling method for endotoxin exposure assessment in farm homes.
| Identifer | oai:union.ndltd.org:uiowa.edu/oai:ir.uiowa.edu:etd-6316 |
| Date | 01 December 2015 |
| Creators | Kilburg-Basnyat, Brita Jane |
| Contributors | Thorne, Peter S. |
| Publisher | University of Iowa |
| Source Sets | University of Iowa |
| Language | English |
| Detected Language | English |
| Type | dissertation |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | Copyright 2015 Brita Jane Kilburg-Basnyat |
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