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

Abstract

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.

Occupational exposure to particulate matter and endotoxin for California dairy workers

“…Our reported geometric mean concentration for personal collected inhalable particulate matter (823 g/m 3 ) and endotoxin (334 EU/m 3 ) was roughly 50% of geometric mean concentrations reported by a study conducted of Wisconsin dairy workers . Higher concentrations were also reported for dairy workers in Colorado and Nebraska, where the inhalable PM fraction was three times higher than what we report for inhalable PM (Burch et al, 2010). In addition the inhalable PM and endotoxin results for personal exposure mean concentrations found here were approximately 60% of those reported from a study conducted in the Netherlands (Spaan et al, 2006).…”

A comprehensive review of levels and determinants of personal exposure to dust and endotoxin in livestock farming

“…86,89 Previous research has demonstrated the presence of different chain lengths in different agricultural dusts, 86,90,91 and indications exist that different chain lengths are associated with different toxicities. 92,93 To date, application of GC-MS has been limited among others because of a lower sensitivity, when compared with the LAL assay, and an increased cost and labor need for performance. 89,90 Recently, a more sensitive and less laborintensive version of the assay has become available.…”

“…Overall, the literature search resulted in 41 publications reporting dust and endotoxin levels from 42 different measurement series among farmers. 12,16,26,90,92, A similar approach was used for literature searches for studies performed in the same period (1980-2012) on determinants of personal exposure to dust and endotoxin using the following terms: personal exposure, exposure determinants, farm characteristics, environmental factors, dust, endotoxin, tasks, pig, poultry, cattle, hog, dust, endotoxin, swine, pig, hog, poultry, broiler, layer, cattle, cow, dairy, farm, farmers, agricultural or agriculture. At least one of the first four of these terms was always included in the searches.…”

“…In total, results from 21 studies were included, all except one being part of the search results on personal levels of exposure. 26,95,100,[102][103][104]106,109,110,[112][113][114][118][119][120]123,[126][127][128][129][130] PERSONAL LEVELS OF EXPOSURE Of the 41 identified studies, 16 were on pig farmers, 16,[95][96][97]101,103,106,109,110,113,114,116,117,123,125,129 7 on poultry farmers 98,100,104,107,118,120,127 and 9 on cattle farmers, 90,92,94,99,105,…”

“…This was true even when looking separately for studies on the inhalable and total particle size fractions, or when restricting the sample to studies with adequate methodological descriptions. 12,26,90,92,95,97,98,104,105,[113][114][115]117,[119][120][121][122][123]127,128 In addition, as recently discussed by Eduard et al, 61 the absence of standardization and reproducibility in measurement methods between studies affects the comparability of the results of epidemiological studies and, subsequently, also the establishment of legal OELs, especially in relation to endotoxin exposure.…”