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Airborne Endotoxin from Indoor and Outdoor Environments: Effects of Sample Dilution on the Kinetic Limulus Amebocyte Lysate (LAL) Assay.

Dungan, R.S. (2011) Airborne Endotoxin from Indoor and Outdoor Environments: Effects of Sample Dilution on the Kinetic Limulus Amebocyte Lysate (LAL) Assay. Journal of Occupatonal and Environmental Hygiene. 8:147-153. 23 February 2011.

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Abstract

Airborne endotoxin in occupational environments are a potential respiratory hazard to individuals. In this study, total and inhalable airborne endotoxin samples were collected via filtration from inside animal housing units and downwind from agricultural production sites and a wastewater treatment plant. Filter extracts were then diluted to examine the effect of interfering substances on the kinetic Limulus amebocyte lysate (LAL) assay. In most cases, the overall endotoxin concentration was shown to decrease with increasing dilution up to 1,000-fold, suggesting the presence of enhancing substances in the filter extracts. This dilution dependent effect was most prominent in the inhalable endotoxin samples, while total endotoxin samples displayed little effect. Using a joinpoint regression model, it was determined that a dilution factor of 50 to 100 was generally sufficient to eliminate the presence of enhancing substances. After screening the data for dilution dependent effects, the airborne endotoxin concentrations were determined. The highest endotoxin concentrations, ranging from 2,841 to 49,066 endotoxin units (EU) m-3 of air, were found inside swine farrowing and finishing barns. Airborne endotoxin concentrations were 10- to 1,000-fold lower inside a dairy barn and downwind of other agricultural production sites and a wastewater treatment plant. Examination of dilution dependent effects should be considered essential when utilizing the LAL assay, especially if values are to be used for regulatory purposes.

Item Type: Article
NWISRL Publication Number: 1380
Subjects: Air Quality > Air Emissions
Air Quality > Air Emissions > Endotoxins
Depositing User: Michelle Wayment
Date Deposited: 23 Feb 2011 23:06
Last Modified: 23 Feb 2011 23:06
Item ID: 1410
URI: https://eprints.nwisrl.ars.usda.gov/id/eprint/1410

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