Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 10/31/1997
Publication Date: N/A
Interpretive Summary: The accuracy of measurements of endotoxin concentrations in the work environment have become critical since the correlation between endotoxin concentration and respiratory problems in cotton textile workers was discovered. The problem is that when duplicate samples are sent to different laboratories for endotoxin measurements, the results obtained are at different levels. This report covers a study to determine between-laboratory differences in test results. The results showed that when different laboratories test almost identical samples for endotoxin content, test values can vary by as much as one or more orders of magnitude. However, within-laboratory variations are very small and ranking of samples with different endotoxin levels can be done reliably. Assays using limulus amebocyte lysate measure only soluble endotoxin, and the concentrations reported are a tenth to a hundreth of the total sample endotoxin. Although rankings of endotoxin concentration can be don reliably in different laboratories under these conditions, a standard method will be required to establish the levels of endotoxin concentration for exposure standards.
Technical Abstract: The vertical elutriator was used to collect airborne cotton dust samples from a cotton card room processing environment. Filter membranes with the same approximate amount and type of cotton dust were analyzed in twelve laboratories that routinely perform endotoxin analyses. Each of these laboratories performed the analysis by methodology used in that laboratory. Test results were analyzed statistically to establish within and between laboratory variations. The within-laboratory variations were small, but large and significant between-laboratory variation was observed. Although rankings of endotoxin concentration can be done reliably in different laboratories under these conditions, a standard method will be required to establish levels of endotoxin concentration for exposure standards.