SECOND INTER-LABORATORY STUDY COMPARING ENDOTOXIN ASSAY RESULTS FROM COTTONDUST

Authors: Chun, David; CHEW, VICTOR - ARS (RETIRED); BARLETT, KAREN - UNIV.BRITISH COLUMBIA; GORDON, TERRY - UNIV.SCHOOL OF MEDICINE; JACOBS, ROBERT - EASTERN VA.MEDICAL SCHOOL; LARSSON, BRITT-MARIE - DEPT.OCCU. MEDICINE; LEWIS, DANIEL - NIOSH; LIESIVUORI, JYRKI - INST.OCCUPATIONAL HEALTH; MICHEL, OLIVIER - UNIV. SAINT-PIERRE; RYLANDER, RAGNAR - UNIV.GOTHENBURG

Submitted to: Annals of Agriculture and Environmental Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2002
Publication Date: 8/1/2002
Citation: Chun, D.T., Chew, V., Barlett, K., Gordon, T., Jacobs, R.R., Larsson, B., Lewis, D.M., Liesivuori, J., Michel, O., Rylander, R., Thorne, P., White, E., Gunn, V., Wurtz, H. Second inter-laboratory study comparing endotoxin assay results from cottondust. Annals Of Agriculture And Environmental Medicine. 2002. AAEM 9(10) p. 49-54.

Interpretive Summary: Further standardization by adopting the same assay protocol, the same endotoxin assay kit and using assay kits from the same production lot, did not sufficiently reduce variation in results between laboratories that results between laboratories were statistically similar. However, intra- laboratory variation is small so comparisons within laboratories would permit internal comparison of samples; and most of the laboratories were able to distinguish between samples having low and high endotoxin concentrations.

Technical Abstract: Previously, a large two-part inter-laboratory round robin endotoxin assay study was completed. This first study showed that when cotton dust samples, which are partically identical, are assayed for endotoxin that the intra-laboratory results had very small variation but that intra-laboratory results of the sample had very high variation. In the first part of the study, each laboratory followed its own in-house assay protocol; but in th second part of the study, when the extraction protocol was standardized, the inter-laboratory results showed lower variation, which suggested that with further standardization, further reduction of differences between laboratories might be achieved so that results between laboratories would become more comparable. The results stimulated interest in extending the study to include cotton dust with two levels of endotoxin, standardization of the extraction protocol and using the same assay kit from the same production lot. The results of this second round robin endotoxin assay study indicate that results between laboratories are still high, but most of the laboratories could discern the cotton dusts with the different levels of endotoxin.