Endotoxin Exposure and Inflammation Markers Among Agricultural Workers in Colorado and Nebraska

• Published in: Journal of Toxicology and Environmental Health, Part A Part A, 2010-01, Vol.73 (1), p.5-22
• Main Authors: Burch, James B., Svendsen, Erik, Siegel, Paul D., Wagner, Sara E., von Essen, Susanna, Keefe, Thomas, Mehaffy, John, Martinez, Angelica Serrano, Bradford, Mary, Baker, Laura, Cranmer, Brian, Saito, Rena, Tessari, John, Linda, Prinz, Andersen, Colene, Christensen, Opal, Koehncke, Niels, Reynolds, Stephen J.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Agriculture; Air Pollutants, Occupational - adverse effects; Albumins; Albumins - analysis; Assaying; Bacteria; Colorado; Constituents; Dust; Endotoxins; Endotoxins - adverse effects; Eosinophil Cationic Protein - analysis; Farming; Farms; Farmworkers; Fatty acids; Human exposure; Humans; Inflammation - chemically induced; Interleukin-8 - analysis; Male; Middle Aged; Nasal Lavage Fluid - chemistry; Nasal Lavage Fluid - cytology; Nebraska; Neutrophils; Occupational Exposure - adverse effects; Peroxidase - metabolism; Respiration; Toxicology; Young Adult
• ISSN: 1528-7394; 1087-2620; 2381-3504
• DOI: 10.1080/15287390903248604

The adverse respiratory effects of agricultural dust inhalation are mediated in part by endotoxin, a constituent of gram-negative bacterial cell walls. This study quantified personal work-shift exposures to inhalable dust, endotoxin, and its reactive 3-hydroxy fatty acid (3-OHFA) constituents among workers in grain elevators, cattle feedlots, dairies, and on corn farms. Exposures were compared with post-work-shift nasal lavage fluid inflammation markers and respiratory symptoms. Breathing-zone personal air monitoring was performed over one work shift to quantify inhalable dust (Institute of Medicine samplers), endotoxin (recombinant factor C [rFC] assay), and 3-OHFA (gas chromatography/mass spectrometry). Post-shift nasal lavage fluids were assayed for polymorphonuclear neutrophils (PMN), myeloperoxidase (MPO), interleukin 8 (IL-8), albumin, and eosinophilic cation protein (ECP) concentrations. The geometric mean (GSD) of endotoxin exposure (rFC assay) among the 125 male participants was 888 ± (6.5) EU/m 3 , and 93% exceeded the proposed exposure limit (50 EU/m 3 ). Mean PMN, MPO, albumin, and ECP levels were two- to threefold 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. Symptom prevalence was not elevated among exposed workers, possibly due to endotoxin tolerance or a healthy worker effect in this population. This is the first study to evaluate the relationship between endotoxin's 3-OHFA constituents in agricultural dust and nasal airway inflammation. More research is needed to characterize the extent to which these agents contribute to respiratory disease among agricultural workers.