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Endotoxin exposure, inflammation markers, and pulmonary function among agricultural workers in Colorado and Nebraska, U.S.A.

Reynolds-SJ; Burch-JB; Wagner-SE; Svendsen-E; Siegel-PD; von Essen-S; Prinz-L; Keefe-T; Mehaffy-J; Bradford-M; Cranmer-B; Saito-R; Koehncke-N
New and Emerging Issues, AIOH 2009 Conference, December 5-9, 2009, Canberra, ACT, Australia. Tullamarine, VIC, Australia: Australian Institute of Occupational Hygienists, Inc., 2009 Dec; :1-15
Endotoxin, a constituent of Gram negative bacterial cell walls is an important mediator of adverse respiratory effects from agricultural dust inhalation. This study quantified personal work shift exposures to inhalable dust, endotoxin and its 3-hydroxy fatty acid (3-OHFA) constituents, and evaluated post-work shift nasal lavage fluid inflammation markers and pulmonary function tests before and after the workshift among workers in cattle feedlots, dairies, grain elevators, and corn farms. Geometric mean dust levels (n = 134) were highest among grain elevator operators (4.50 mg/m3) and lowest among farm workers (2.49 mg/m3), whereas geometric mean endotoxin exposure level was highest among feedlot workers (1,093 EU/m3). Livestock dusts contained approximately two times higher concentrations of 3-OHFAs than grain dusts. Patterns of 3-OHFA distribution and proportion of each individual 3-OHFA varied by dust type. Mean PMN, MPO, albumin and ECP levels were 2-3-fold higher among workers in the upper quartile of 3-OHFA exposure compared to the lowest exposure quartile. Even numbered 3- OHFA were most strongly associated with nasal inflammation. 10% of the population with pulmonary function tests (total n = 174) had baseline FEV1 and FEV1/FVC below criteria used to clinically define obstructive lung disease. Close to 50% of the population had FEV1and FEV1/FVC less than 95% of predicted - a significant effect for the population from an epidemiological standpoint. Cross shift pulmonary function dropped more than 5% in 26% of the population and more than 10% in 10% of the population. 19% had a drop in FVC exceeding 5% and 8% had an FVC decrease exceeding 10%. The proportions were largest in farmers, followed by dairy workers and grain handlers. Both correlations and regression models indicated that smoking, endotoxin/dust exposure, facility type were significant predictors of symptoms (eye and throat irritation, cough) and pulmonary function (cross shift decrease in FEV1, pre-shift FVC and FEV1). These results suggest that workers with less chronic exposure to work environments with elevated ambient concentrations of endotoxin containing dusts are more susceptible to the acute effects of endotoxin and that extended workplace exposures confer a degree of resistance to the effects of endotoxin, or that sensitive workers who do not adapt leave the industry over time.
Agricultural-industry; Agricultural-processes; Agricultural-workers; Agriculture; Air-monitoring; Air-sampling; Air-sampling-techniques; Cell-biology; Cellular-reactions; Chronic-exposure; Dust-inhalation; Dust-measurement; Dust-particles; Epidemiology; Exposure-assessment; Exposure-methods; Inhalation-studies; Particulate-dust; Particulates; Respiratory-hypersensitivity; Respiratory-irritants; Respiratory-system-disorders; Statistical-analysis; Work-environment; Workplace-studies; Author Keywords: endotoxin; 3-hydroxy fatty acid; nasal lavage; organic dust; pulmonary function
Publication Date
Document Type
Conference/Symposia Proceedings
Funding Type
Grant; Cooperative Agreement
Fiscal Year
Identifying No.
Grant-Number-R01-OH-007841; Cooperative-Agreement-Number-U50-OH-008085
NIOSH Division
Priority Area
Agriculture, Forestry and Fishing
Source Name
New and Emerging Issues, AIOH 2009 Conference, December 5-9, 2009, Canberra, ACT, Australia
Performing Organization
Colorado State University - Ft. Collins
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division