Theses and Dissertations
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Browsing Theses and Dissertations by Subject "agriculture"
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Item Open Access Analyses and exposure assessment of bacterial endotoxin in agricultural environments(Colorado State University. Libraries, 2008) Saito, Rena, author; Reynolds, Stephen J., advisorEndotoxins, or lipopolysaccharides (LPS), found in organic dust are a component of the cell membrane of Gram-negative bacteria that play an important role in respiratory disease. However, accurate endotoxin measurements are difficult in agricultural environments since agricultural dusts contain a complex mixture of biological and chemical agents. This dissertation research was designed to improve the understanding of the variability in endotoxin measurements in agricultural environments. The first study determined patterns of 3-OHFA distribution in dusts from dairy farms, cattle feedlots, grain elevators, and farms, and evaluated correlations between the GC/EI-MS and the rFC bioassay results. Patterns of 3-OHFA distribution varied by dust type; livestock dusts contained approximately two times higher concentrations of 3-OHFAs than grain dusts. Pearson correlations and multiple regressions showed higher correlations between GC/EI-MS and rFC results for livestock dusts than for grain dusts. Odd-chain length 3-OHFAs were found to correlate with rFC responses, as well as with even-chain length 3-OHFAs. The second study evaluated traditional LAL and novel rFC assay responses to endotoxins in chicken, dairy, horse, swine, and turkey dusts, and investigated potential interference with assays using GC/EI-MS. Strong positive correlations existed between LAL and rFC results, but responses to assays varied by dust type. LAL overestimated/rFC underestimated endotoxin exposures in chicken and horse dusts, and LAL underestimated/rFC overestimated endotoxin concentrations in dairy, swine, and turkey dusts. The variability in assay responses might be explained by differences in bacterial composition and other dust components; the rFC assay may react positively with Actinobacteria. The third study characterized agricultural tasks and evaluated determinants of personal dust and endotoxin exposures in dairy farms, cattle feedlots, grain elevators, and farms. Dust and endotoxin exposures differed by agricultural environment and by task and combinations of tasks varied by environment. Regression analysis indicated that hours at running legs in grain elevators was the major determinant of dust. Hours at running legs in grain elevator and hours at feeding livestock in cattle feedlots were two major determinants in endotoxin measurements. This dissertation addressed the need for understanding differences in agricultural environments for endotoxin exposure assessment.Item Open Access Analysis of agriculture injuries using workers' compensation data(Colorado State University. Libraries, 2008) Douphrate, David Irvin, author; Rosecrance, John C., advisorBackground. In the United States, agriculture is among the most hazardous of industries. The lack of information regarding agriculture injuries has been recognized as an obstacle to effective injury prevention efforts. Methods. Three separate but related studies analyzed workers' compensation data to elucidate injury and claimant characteristics associated with agriculture injuries. Specific emphasis was placed on tractor-related and livestock-handling injuries. Results. Results indicated high injury rates among workers employed by dairy farms, cattle/livestock raisers, and cattle dealers. Large proportions of injuries were associated with tractor mounting and dismounting, milking, cattle pinning/sorting, and horseback riding activities. Tractor-related and livestock-handling work injuries are a significant problem, more costly, and result in more time off work than other agriculture injuries. Conclusions. Injury prevention efforts should be directed at livestock-handler education, dairy parlor and livestock-handling facility design, and tractor design characteristics related to tractor mounting and dismounting.Item Open Access Comparison of occupational and environmental exposures at Colorado dairies(Colorado State University. Libraries, 2008) Lester, Bradley Raymond, author; Reynolds, Stephen J., advisorOccupational contaminant levels and environmental emissions were compared at two Colorado dairies. Along with meteorological conditions, analytes measured included odor, hydrogen sulfide, ammonia, total and inhalable particulate and endotoxin, and bioaerosols including fungi, mesophilic bacteria, and gram-negative bacteria. Meteorologic conditions varied widely in temperature (range: -12.5 - 4 1.1°C), relative humidity (range: 0.6 - 92.3%) and wind speeds during sampling (range: 0.48 - 8.66 m/s). Geometric mean bioaerosol concentrations for the Anderson sampler and SKC Biosampler include: mesophilic bacteria, 1282 and 383 CFU/m3, gram-negative bacteria, 667 and 265 CFU/m 3, and fungi, 781 and 252 CFU/m3. The Anderson sampler collected significantly (p<0.001) higher bioaerosol concentrations for all three categories. Peak ammonia levels at the study and control dairies ranged from 2.0 - 142 and 2.0 - 23 ppm. Peak ammonia was significantly (p<0.05) higher at the study dairy. Mean hydrogen sulfide levels at the study and control dairies ranged from 4.0 - 394 and 4.0 - 890 ppb. Peak hydrogen sulfide levels at the study and control dairies ranged from 37 - 17,000 and 210 - 5,200 ppb. Mean peak hydrogen sulfide was significantly (p<0.05) higher at the control dairy. Odor measures ranged from 0-15 D/T at both dairies. Inhalable particulate at study and control dairy lagoons ranged from < LOD - 2.3 mg/m3. Inhalable endotoxin at study and control dairy lagoons ranged from 2.1 - 487.2 EU/m3. Total particulate at study and control dairy lagoons ranged from < LOD to 2.4 mg/m3. Total endotoxin at study and control lagoons ranged from 2.5 - 6587 EU/m3. Inhalable particulate for tasks at both dairies ranged from 0.06 - 8.0 mg/m3. Total particulate for tasks at both dairies ranged from 0.03 - 6.9 mg/m 3. Inhalable endotoxin for tasks at both dairies ranged from 2.0 - 11096 EU/m3. Total endotoxin for tasks at both dairies ranged from 5.9 - 6758 EU/m3. Supported by NIOSH Grant 5U500H008085.Item Open Access Uranium contamination values and limits(Colorado State University. Libraries, 2012) Miaullis, Aaron Paul, author; Johnson, Thomas, advisor; Brandl, Alexander, advisor; Borch, Thomas, committee memberHypothesis: Current soil contamination limits for non-enriched uranium are not consistent and are not optimized to allow the beneficial use of uranium while protecting the health of the public. Objective: Assess available health impact data regarding non-enriched uranium ingestion and inhalation as well as past soil contamination recommendations to determine if the regulatory limits for uranium are optimized, as recommended by the ICRP. Provide supporting data for keeping current soil contamination limits for non-enriched uranium, or suggest new limits based upon chemical uptake ratios.