Browsing by Author "Reynolds, Stephen, committee member"
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Item Open Access A study of fumed silica particle deagglomeration associated with instrument sampling techniques and A comparison of NIOSH 7402 and the Tsai Diffusion Sampler for collecting and analyzing carbon nanotubes(Colorado State University. Libraries, 2018) Khattak, Jared, author; Tsai, Candace Su-Jung, advisor; Reynolds, Stephen, committee member; Jathar, Shantanu, committee memberAccurate characterization of contaminant exposures is critical in ensuring worker safety. Worker exposures are commonly characterized by area monitoring and personal samples. This research includes two parts, which study real time instrument measurements and personal sampling methods for exposure assessment. Real time instruments (RTIs) are used to assess concentrations of airborne particles in manufacturing facilities. These instruments often contain a cyclone, and previous studies have shown that the cyclone may cause measurement variations by dispersing agglomerated particles. This mechanism is thought to increase particle concentrations and decrease particle size. To determine the cyclone effect in this study, three RTIs were evaluated; the scanning mobility particle sizer (SMPS), fast mobility particle sizer (FMPS), and the optical particle sizer (OPS). The SMPS and FMPS contain a cyclone, the OPS does not. Nanoparticles were generated and sampled through pouring and automatic stirring inside a glovebox enclosure. After particles were generated, the glovebox was thoroughly cleaned and measurements were taken in the glovebox. For both generation methods, the SMPS and FMPS recorded an average concentration of 1.2 x 103 particles/cm3 and 1.7 x 104 particles/cm3 more after runs where the cyclone was used than when the cyclone was not used. The OPS, which does not contain a cyclone, recorded minimal differences during the measurement period after the glovebox was cleaned when the cyclone was used and not used on the other instruments. This result indicated that the measured nanoparticle concentrations increased with cyclone use. The results of this study indicate that the cyclone does influence the concentrations recorded by RTIs, and should be cleaned to ensure accurate measurements. The personal sampling methods evaluated were the NIOSH 7402 method for collecting and analyzing Carbon Nanotubes (CNTs) and the Tsai Diffusion Sampler (TDS) method for sampling CNTs. To evaluate each sampling method, CNTs were generated in a small enclosure inside of a glovebox; CNTs were generated by manual stirring. RTIs also sampled during each experiment to provide an estimate of airborne CNT concentrations. Airborne concentrations were estimated using the particle counts from TEM grid samples prepared using both methods. The majority of CNT structures collected by the TDS were individual fibers and clusters smaller than one micron in diameter. The NIOSH 7402 sampler primarily collected larger agglomerates, with the majority of collected particles being larger than two microns in diameter. The average estimated airborne concentrations calculated from the TDS and 7402 method particle counting were 5,200 fibers/cm3 and 59 fibers/cm3 respectively. During the experiments the SMPS recorded an airborne concentration of 1,100 particles/cm3 and the OPS measured an airborne concentration of 33 particles/cm3. Because the concentrations measured by the RTIs significantly exceeded the estimated concentrations derived from the NIOSH 7402 method, it is recommended that the TDS sampler be used as the concentrations derived from this sampler would warrant a more conservative approach to worker safety.Item Open Access Assessment of fine particles released from paper printing and shredding processes(Colorado State University. Libraries, 2019) Shin, Nara, author; Tsai, Candace Su-Jung, advisor; Reynolds, Stephen, committee member; Tong, Tiezheng, committee memberIn this study, we investigated the airborne particles released during paper printing and paper shredding processes in an attempt to characterize and differentiate these particles. Particle characteristics were studied with real-time instruments (RTI) to measure concentrations and with samplers to collect particles for subsequent microscopy and cytotoxicity analysis. The particles released by paper shredding were evaluated for cytotoxicity by using in vitro human lung epithelial cell models. A substantial amount of particles were released during both the shredding and printing processes. We found that the printing process caused substantial release of particles with sizes of less than 300 nm in the form of metal granules and graphite. These released particles contained various elements including Al, Ca, Cu, Fe, Mg, N, K, P, S, and Si. The particles released by the paper shredding processes were primarily nanoparticles and had a peak size between 27.4 nm and 36.5 nm. These paper particles contained elements including Al, Br Ca, Cl, Cr, Cu, Fe, Mg, N, Na, Ni P, S, and Si, as determined by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) and single-particle inductively coupled plasma-mass spectroscopy (SP-ICP-MS) analysis. Although various metals were identified in the paper particles, these particles did not elicit cytotoxicity to simian virus-transformed bronchial epithelial cells (BEAS2B) and immortalized normal human bronchial epithelial cells (HBE1). However, future studies should investigate other cytotoxicity effects of these paper particles in various types of lung cells to identify the potential health effects of the particles.Item Open Access Comparison of hexavalent chromium and welding fumes inside and outside of the welding helmet(Colorado State University. Libraries, 2013) Diaz-Rivera, Karen, author; Brazile, William, advisor; Reynolds, Stephen, committee member; Collett, Jeffrey L., committee memberThe primary objective of this study was to determine if welding fumes and specific metal concentrations were significantly different between samples taken inside and outside of the welding helmet to determine the most appropriate location of the personal sampling device and best estimate exposure. Personal air samples were collected simultaneously inside and outside of the welding helmet for concentration comparison of welding fumes (n = 12) and hexavalent chromium (n = 15) during stainless steel tungsten inert gas welding tasks. A total of fifteen welders were sampled in a manufacturing setting and a brewery for a total of 27 inside and outside paired samples. A statistically significance difference (p = 0.05) between inside and outside welding helmet concentrations was found for total welding fumes, iron, total chromium, and nickel using a Wilcoxon paired test, where most of the inside-helmet concentrations were lower. Hexavalent chromium and manganese concentrations were not significantly different when comparing inside and outside welding helmet concentrations. A correlation among welding fumes, iron, nickel, and total chromium concentrations was observed utilizing Spearman's rank-order correlation. The mean for hexavalent chromium concentrations difference was 11 μg/m3, when the outlier was included in the analysis and 0.07 μg/m3 without the outlier. The median concentrations difference was 0.06 μg/m3 with or without the outlier in the analysis. The 95% confidence interval for hexavalent chromium inside concentration was 0.1 μg/m3 to 0.34 μg/m3 and 0.13 μg/m3 to 0.4 μg/m3 for outside of the welding helmet concentration. One sample set for hexavalent chromium exceeded the permissible exposure limit (PEL), recommended exposure limit (REL), and threshold limit value (TLV). Based on the results, a high variation of concentrations was found between the inside and outside of the welding helmet concentrations depending on the metal fume analyzed. Manganese had the lowest metal content in the stainless steel welding rods as well as the sampled welding fumes. The greatest variation in concentration ratios was observed for manganese and hexavalent chromium when comparing inside and outside concentrations. These two factors, lower metal contribution in welding rods and variation in concentrations can be speculated to affect the statistical non significant difference found for manganese and hexavalent chromium inside and outside of the welding helmet concentrations. The welding helmet seemed to be protective for some metals, but it should not be assumed that protection will be provided by the use of it. As for sampling location for best welding fumes assessment monitoring, it is recommended that sampling is done outside. Welders often remove their welding helmets to verify the weld, and inside of the welding helmet sampling location may be compromised as it may change when the welding helmet is in the upward position.Item Open Access Comparison of indoor air quality between building type in campus buildings(Colorado State University. Libraries, 2018) Erlandson, Grant, author; Schaeffer, Joshua, advisor; Carter, Ellison, committee member; Magzamen, Sheryl, committee member; Reynolds, Stephen, committee memberThe average American spends an estimated 90% of their time indoors on any given day. Rapid urbanization is also sweeping the country leading to ever increasing time spent in the built environment. Human exposure to the surrounding environment accounts for 90% of all disease. The air we breathe represents a major component of that exposure and becomes increasingly relevant as more time is spent indoors. Many studies have set out to characterize and improve indoor air quality in various settings from the workplace to schools. However, few have investigated higher education and its shift toward green, sustainable buildings. The objective of this research was to evaluate the effects of building type and occupancy on indoor air quality in higher education buildings. We measured LEED certified, retrofitted, and conventional building types on a college campus for particulate matter, formaldehyde, carbon dioxide, and nitrogen oxides. For each building type, we conducted multi-zonal, 48 hour measurements during times when the buildings were occupied and unoccupied. Statistically significant differences in two size fractions of particulate matter were observed between building types. Carbon dioxide and particulate matter concentrations were significantly higher during occupied sampling when compared to unoccupied. Results from this study suggest that occupancy status has a larger impact on indoor air quality in campus buildings than building type.Item Open Access CSU industrial hygiene program training needs analysis(Colorado State University. Libraries, 2022) Moore, Jillian, author; Brazile, William, advisor; Zarestky, Jill, committee member; Reynolds, Stephen, committee memberGraduates of industrial hygiene (IH) programs must be able to meet continuously evolving health and safety needs in a wide variety of occupational settings. Therefore, academic IH graduate programs must regularly evaluate their curricula and solicit input from industry professionals in order to make curricular changes that will better prepare their students for professional roles in industry. The purpose of this study was to identify the training gaps that exist between industry needs, accreditation criteria, and the current curriculum for the CSU Industrial Hygiene graduate program. In Phase 1 of this study, a set of curriculum maps were developed to evaluate training gaps between accreditation criteria, course learning objectives, and course assessment mechanisms for each core course in the IH curriculum. In Phase 2, the research team facilitated two group interviews with the Colorado State University (CSU) IH Advisory Board, collected alumni survey data, and performed a qualitative analysis to identify skills gaps/needs for CSU IH Program graduates. In Phase 1, only one gap was identified between accreditation criteria and IH program course objectives in the nine core departmental courses of the CSU IH graduate curriculum. No gaps were found between IH Program course objectives to course assessment mechanisms. In Phase 2, the research team identified three themes (technical, applied, and soft skills) and selected several skills within each theme that interview participants thought were necessary proficiencies for young IH professionals. The curriculum mapping exercise generally validated the satisfactory accreditation status of the CSU IH Program graduate curriculum. The development of the curriculum mapping tool and evaluation method can aid in providing evidence for the re-accreditation process for the CSU IH Program, as well as other occupational health programs. The skills identified in the qualitative interview and survey data can be incorporated into the curriculum to improve the training of IH students. Additionally, by using qualitative analysis, the researchers uncovered soft skills previously unidentified in IH needs assessments, providing valuable information for all IH graduate programs.Item Open Access Design of an inhalable aerosol size spectrometer(Colorado State University. Libraries, 2015) Ndonga, Mwangi, author; Volckens, John, advisor; Reynolds, Stephen, committee member; Kreidenweis, Sonia, committee memberIndustrial hygienists lack the proper instruments to measure size distributions of inhalable particulate matter (0-100 μm) as defined by ACGIH/ISO/CEN. The Portable Inhalable Particle Spectrometer (PIPS) was designed to size-segregate IPM in calm-air environments – which constitute a majority of workplaces. The PIPS uses an upward air velocity to restrict particle aspiration into the device to diameters above a specified cut-size. A vertical test chamber was also designed to facilitate aerosol dispersion and experimental evaluation of the PIPS. Two PIPS tubes were tested (1.5 cm and 5 cm) at four face velocities (0.6, 1.35, 2.5 and 3.5 cm·s⁻¹) that correspond to cut-sizes of 20, 30, 40 and 50 μm in aerodynamic diameter, respectively. The observed performance of the PIPS deviated from model estimates as face velocity or tube diameter was increased. The fluid regime present inside the chamber, due to the operating PIPS, likely influenced the measured sampling efficiency of the PIPS.Item Open Access Developing an integrated livestock-human infectious disease management framework for the dairy farm environment(Colorado State University. Libraries, 2023) Fathke, Robert, author; Rao, Sangeeta, advisor; Pinedo, Pablo, committee member; Reynolds, Stephen, committee member; Duncan, Colleen, committee memberThis research aimed to develop a framework integrating cattle and human infectious disease prevention in the dairy farm environment. Infectious disease dynamics on dairy farms can be complex, with various factors impacting cattle and human health. The advent of the COVID-19 pandemic reminded the world of the complexities of disease dynamics and prevention. Biosecurity is key to infectious disease prevention on dairy farm settings, but preventive efforts might not focus on both cattle and human health. Those trained in veterinary medicine may be especially suited to help bridge this animal-human gap on dairy farms, as these professionals understand disease dynamics and may be trusted to serve in this capacity. Infectious disease risk assessment tools for dairy farms might not fully integrate human health. Developing more integrated risk assessment tools first requires a greater understanding of existing tools and dairy farmer knowledge, attitudes, and practices regarding cattle and human infectious disease prevention. The research described biosecurity, biosafety, and identified potential areas of overlap to create a foundational integrated animal-human infectious disease prevention model. A systematic literature review was conducted on animal producer knowledge, attitudes, and practices regarding personal protective equipment for zoonotic disease prevention. Current biosecurity and biosafety assessment surveys and tools applicable to dairy farm environment were also assessed for structure, content, and degree of human health integration. Assessment of the survey questions and score report from one of these tools included obtaining feedback from a small sample of Front Range Colorado dairy producers. A knowledge, attitudes, and practices questionnaire including elements of cattle and human infectious disease prevention was developed, and data was collected from 50 personnel, including workers and supervisors, across six Front Range Colorado dairy farms. This work found that the word "biosecurity" has many definitions that can vary by profession setting. Many elements of efforts aimed at preventing animal diseases can also be effective in preventing human diseases. Personal protective equipment is an example of such an element. Systematically reviewing literature on personal protective equipment knowledge, attitudes, and practices revealed that animal producers often fail to use preventive measures and may not always perceive zoonoses as a threat. Assessment of existing infectious disease risk assessment tools revealed that none fully and directly integrated human infectious disease prevention. Producer feedback on one tool focusing on cattle health provided valuable feedback on tool design and helped shape recommendations for developing integrated tools. Construction of the integrated knowledge, attitudes, and practices questionnaire was a novel approach to creating a research tool that integrates animal and human infectious disease prevention. Results revealed strengths and weaknesses in knowledge, attitudes, and practices regarding zoonotic disease prevention and helped identify elements that can be addressed to develop a shared understanding between dairy farm supervisors and workers.Item Open Access Development and application of an improved in vitro model for aerosol toxicology(Colorado State University. Libraries, 2014) Hawley, Brie, author; Volckens, John, advisor; Dow, Steven, committee member; Ryan, Elizabeth, committee member; Reynolds, Stephen, committee memberIn vitro cellular studies offer an economical and rapid screening tool for assessing aerosol toxicity. Traditional submerged in vitro cell models and exposure techniques are often criticized for their inability to (1) simulate in vivo cellular morphology (2) maintain the chemical and physical characteristics of sampled aerosol and (3) estimate 'delivered' exposure levels. Further, the exposure levels applied in traditional submerged in vitro systems are often orders of magnitude above inhalational exposures that occur in vivo. Improved airway cell culture models and direct air-to-cell exposure systems have been developed over the last few decades; these improvements offer greater 'real-world' significance to in vitro aerosol toxicology. Air-liquid interfaced airway cell cultures offer greater physiological relevance than previous, submerged cell cultures. Further, direct air-to-cell exposure systems offer the ability to (1) better maintain the chemical and physical characteristics of test aerosols and (2) more closely control and approximate exposure levels. Presented here, are two improved direct air-to-cell aerosol exposure systems that rely upon electrostatic deposition or gravitational settling to directly expose well-differentiated airway cell cultures to three different aerosols of interest, with regard to occupational and environmental health. The first and second study presented here used electrostatic deposition to expose well-differentiated normal human bronchial epithelial cells to diesel particulate matter and complete diesel exhaust. Cells were exposed to either (1) diesel particulate matter or (2) complete diesel exhaust from an engine run on either petro- or biodiesel, and with and without a diesel particulate filter. Cellular response was assessed by measuring transcripts associated with inflammation, oxidative stress, aromatic hydrocarbon response and overall cellular dysfunction at 1, 3, 6, 9, and 24 hours after exposure to diesel particulate matter. Cellular response to complete diesel exhaust was assessed by measuring transcripts associated with oxidative stress and aromatic hydrocarbon response at two hours after exposure. The main aims of these two studies were to (1) characterize the time course of the proinflammatory response of normal human bronchial epithelial cells after exposure to diesel particulate matter and (2) screen for the effects of exposure to petro- and biodiesel exhaust, with and without a diesel particulate filter. The third study presented here used gravitational settling to expose well-differentiated human bronchial or nasal epithelial cells to two different particle size fractions from inhalable dust collected at a local dairy parlor. Cellular response was assessed by measuring transcripts associated with inflammation at two hours after exposure. Cell compromise was also measured in all three studies by measuring percent lactate dehydrogenase release. Significant airway cellular responses were observed in all three studies, at levels of exposure far lower than reported in previous traditional in vitro studies. Results from the work presented here strongly support the use of improved airway cell models and direct air-to-cell exposure systems in future in vitro studies in aerosol toxicology.Item Open Access Evaluation and resolution of two sampling methods for airborne aromatic diisocyanate monomers(Colorado State University. Libraries, 2013) Schaeffer, Joshua W., author; Brazile, William, advisor; Reynolds, Stephen, committee member; Sandfort, Delvin, committee member; Hanneman, William, committee member; Morley, Paul, committee memberTo view the abstract, please see the full text of the document.Item Open Access "Exposure to respirable crystalline silica during five OSHA Table 1 tasks and the effectiveness of dust controls, the contribution of background silica dust to personal exposures, and the use of a photometric instrument to assess silica dust exposure in real time"(Colorado State University. Libraries, 2021) Cothern, Emily J., author; Brazile, William, advisor; Reynolds, Stephen, committee member; Autenrieth, Daniel, committee member; Fisher, Gwen, committee memberTo view the abstract, please see the full text of the document.Item Open Access Indoor hockey officials' noise exposure, temporary hearing loss, and effect of helmet visor length on exposure to whistle noise(Colorado State University. Libraries, 2016) Adams, Karin L., author; Brazile, William, advisor; Reynolds, Stephen, committee member; Peel, Jennifer, committee member; Legare, Marie, committee member; Lipsey, Tiffany, committee memberTo view the abstract, please see the full text of the document.Item Open Access Investigation of the beef supply-chain microbiome and pathogen controls(Colorado State University. Libraries, 2015) Yang, Xiang, author; Belk, Keith, advisor; Woerner, Dale, committee member; Yang, Hua, committee member; Reynolds, Stephen, committee memberFoodborne illness associated with pathogenic bacteria is a global public health and economic challenge. Understanding the ecology of foodborne pathogens within the meat industry is critical to mitigating this challenge. The diversity of microorganisms (pathogenic and non-pathogenic) that exists within the food and meat industries complicates efforts to understand pathogen ecology. Further, little is known about the interaction of pathogens within the microbiome throughout the whole meat production chain. Here, the combined use of a metagenomics approach and shotgun sequencing technology was evaluated as a tool to detect pathogenic bacteria in different sectors of the beef production chain. Environmental samples were obtained at different longitudinal processing steps of the beef production chain: cattle entry to feedlot (Arrival), exit from feedlot, cattle transport trucks, abattoir holding pens, and the end of fabrication system (Market-Ready). The log counts population per million reads for all investigated pathogens (Salmonella enterica, Listeria monocytogenes, generic Escherichia coli, Staphylococcus aureus, Clostridium (C. botulinum, C. perfringens), and Campylobacter (C.jejuni, C.coli, C.fetus)) were reduced from Arrival to Market-Ready samples mainly due to reduced diversity within the microbiome. Further, normalized counts for Salmonella enterica, E. coli, and C. botulinum were greater in Market-Ready samples. This indicates that the proportion of these bacteria increases within the remaining bacterial community, which is likely a result of a reduction or elimination of other bacteria via antimicrobial interventions applied during meat processing. Further characterization of the microbiome allowed for the identification of 63 virulence factors within 27 samples (31% of samples). From an ecological perspective, data indicated that shotgun metagenomics can be used to evaluate not only the microbiome of samples collected from the beef production system, but also observe shifts in pathogen populations during the beef production chain over time. However, our utilization of this approach presented challenges and highlighted a need for further refinement of this methodology. Specifically, identifying the origin of reads assigned to specific pathogen from a diverse environmental sample containing thousands other bacterial species can be difficult. Additionally, low coverage on pathogen whole genome is another limitation of current next generation sequencing technology for shotgun metagenomic data. Moreover, the identification of bacteria from metagenomic data relies heavily on the quality of public genome database, which still need to be improved. Our investigation demonstrates that although the metagenomic approach has promise, further refinement is needed before it can be used to confirm the presence of pathogens in environmental samples. A study was conducted to compare decontamination efficacy of a blend of sulfuric acid and sodium sulfate (SSS) or lactic acid (LA) against Salmonella on the surface of hot beef carcasses. A total of 60 pieces of beef briskets, obtained directly from unchilled beef carcasses, were cut into two sections (10 x 10 x 1 cm) and spot-inoculated with 200µl of inoculum, comprised of six-strain mixtures of Salmonella, and allowed 15 minutes for pathogenic attachment to reach a target level of approximately 5 to 6 log CFU/cm2. One brisket section (of the pair) remained untreated while the other section was treated with the compounds using a custom-built spray cabinet that sprays either SSS (21°C and 52°C) or LA (21°C and 52°C) at pressure of 15 psi for 5 seconds. Treated samples were transferred into Whirl-Pak filter bags and were held for 10 minutes, allowing pathogen bacterialcidal activity before sampling, plating, and counting. Unheated and heated SSS lowered (P < 0.05) means of the total bacterial counts on Tryptic Soy Agar (TSA) from 6.3 log CFU/cm2 to 4.6 and 4.3 log CFU/cm2, respectively. Likewise, unheated and heated LA reduced (P < 0.05) means of the total bacterial counts on TSA from 6.3 log CFU/cm2 to 4.7 and 4.4 log CFU/cm2, respectively. On Xylose lysine deoxycholate agar (XLD), initial counts of inoculated Salmonella (6.1 to 6.2 log CFU/cm2) were reduced (P < 0.05) by 2.0 to 4.2 log CFU/cm2 due to treatment with unheated SSS, by 2.3 to 3.9 log CFU/cm2 due to treatment with heated SSS, by (P < 0.05) 2.4 to 3.7 log CFU/cm2 and 3.8 log CFU/cm2 after treatment with unheated and heated LA, respectively. Overall, no (P > 0.05) chemical by temperature interaction effects on microbial reductions was detected when plated on either TSA or XLD agars. Heating chemical solutions lead to an additional 0.3 log CFU/cm2 reduction in total aerobic bacteria compared to unheated solutions. Less (0.3 log CFU/cm2) inoculated Salmonella were recovered on XLD agar from samples treated with LA compared to samples treated with SSS. However, such a small numeric unit change was likely not biologically important. These results indicated that both unheated and heated SSS and LA are effective interventions to reduce Salmonella inoculated onto hot beef carcass surface tissue.Item Open Access Is the "grass" greener? Occupational wellness in the Colorado cannabis industry(Colorado State University. Libraries, 2016) Walters, Kevin M., author; Fisher, Gwenith, advisor; Dik, Bryan, committee member; Kraiger, Kurt, committee member; Reynolds, Stephen, committee memberThis study is the first occupational safety and health evaluation of the cannabis industry of Colorado from an Occupational Health Psychology (OHP) perspective. Qualitative pilot data and common OHP theories provide a framework for project development, design, and rationale. This study investigated the following among cannabis industry workers: potential stressors, perceptions and awareness of physical safety hazards, strain outcomes, and organizational supports that might buffer relations between stressors and strain outcomes. Study results provide a first glimpse at the demographics of the cannabis industry and suggest that workers generally experience low strain and high levels of organizational supports in the presence of various physical and psychological stressors and hazards. However, results also suggest heterogeneous health and safety training, awareness, and regulation in the cannabis industry. Future research directions and practical implications for cannabis industry workers are provided.Item Open Access Longitudinal analysis and characterization of Escherichia coli O157:H7 shedding in dairy cattle in northern Colorado(Colorado State University. Libraries, 2016) Burket, Victoria L., author; Magzamen, Sheryl, advisor; Reynolds, Stephen, committee member; McConnel, Craig, committee memberEscherichia coli O157:H7 (STEC) is an enterohemorrhagic Gram-negative bacteria that is a common source of foodborne illness around the world. Annually, O157 is responsible for approximately 100,000 cases, 3,000 hospitalizations, and 90 deaths in the United States, and has been diagnostically confirmed on every continent except for Antarctica. Dairy cattle serve as asymptomatic carriers of the O157 bacteria, maintaining a continuous cycle of reinfection through their environment, and have been implicated as a potential source of contamination of the food chain. Gathering data on prevalence and shedding cycles of O157 in dairy cattle can provide insight into the scope of the problem and potential mitigation strategies. The primary objective of this study was to investigate the association between shedding status on a randomly selected day and- shedding on subsequent consecutive days (n=4), daily proportions and patterns of shedding, and how shed status on one day affects shed status on the next day. Two local Northern Colorado dairies were selected for study. Fecal samples were taken from 25 cows from Dairy A and 49 cows from Dairy B and tested for presence of the O157 pathogen. Based on those results, twenty cows from each dairy were randomly chosen for the study, with 10 “shedders” (i.e. cows that tested positive for O157 on Day 1) and 10 “non-shedders” (i.e. cows that tested negative for O157 on Day 1) selected from each dairy for a total of forty study subjects. The cows were then resampled once daily for an additional four days, testing for rfb, stx1, stx2, and eae genes as well as collecting overall health information. Health information variables were dichotomized based on scoring systems and logistic regression, generalized linear models, and generalized linear mixed models were used for analysis of research questions. Our study had three main aims and five research questions of interest. Our first aim was to analyze overall shedding events, split into two research questions. First we wanted to know if shedding status on Day 1 was associated with shedding on any subsequent day. We used a logistic regression model with any subsequent shedding as the outcome and Day 1 shedding status, dairy, parity, temperature, days in milk, body condition score, hygiene score, and fecal score as the covariates. Next, we wanted to know what risk factors were associated with cumulative days of shedding. For this question we used a generalized mixed model with a poisson regression. The count of total shedding days was used as the outcome variable and Day 1 shedding status, dairy, parity, temperature, days in milk, body condition score, hygiene score, and fecal score were the covariates. Additionally, we aimed to analyze day-to-day shedding patterns within the cattle cohort so see if shedding status on one day was associated with shedding status on the next day. First we used a generalized linear mixed model to compare paired days, specifying Day 1 vs Day 2, Day 2 vs Day 3, Day 3 vs Day 4, and Day 4 vs Day 5. The outcome variable was daily shedding status and the primary risk factor was shedding status on the stated previous day, with additional variables including Day 1 shedding status, dairy, parity, temperature, days in milk, body condition score, hygiene score, and fecal score were the covariates. We then used a generalized linear model with a logit link to assess the overall association between day-to-day shedding patterns averaged over the five-day study period, with the outcome variable as daily shedding status. The primary risk factor was shedding status on the previous day, with additional variables including Day 1 shedding status, dairy, parity, temperature, days in milk, body condition score, hygiene score, and fecal score were the covariates. Our last research question aimed to assess the associations between our risk factors of interest and daily shedding status, as well as daily shedding patterns. We used a generalized linear model with a logit link to model risk factor associations, with the outcome variable being daily shedding status and the risk factor variables including Day 1 shedding status, dairy, parity, temperature, days in milk, body condition score, hygiene score, and fecal score. We then used proportion testing to assess the differences in proportions of gene and shedding prevalence between Day 1 Shedders and Day 1 Non-Shedders. Initial shedders had a higher proportion of daily shedding than non-shedders during every sample day, 60% vs 35% on Day 2, 60% vs 45% on Day 3, 50% vs 30% on Day 4, and 45% vs 35% on Day 5, however none of these were statistically significant. Shedders similarly also had a higher overall prevalence of targeted O157 genes than Non-Shedders; 20% vs 10% for Stx1, 35% vs 30% for Stx2, and 30% vs 20% for eae. There were no significant differences in gene prevalence between cows from Dairy A and cows from Dairy B for Stx1 or eae, but there was for Stx2; 15% for both groups for Stx1, 25% vs 40% for Stx2, and 25% for both groups for eae. Cows in the Shedder cohort were twice as likely to shed O157 on any subsequent sampling day than non-shedders based on logistic regression analysis (OR 2.0, 95% CI: 1.1,3.8). Day 1 shedding status (p <0.0001), fecal score >3 vs 3 (p 0.02), and temperature (p 0.04) were significantly associated with an increase in cumulative days of shedding. Day 1 shedding status was also a significant predictor of daily shedding status (OR: 1.7, 95% CI: 1.1,2.5). Interestingly, shedding status on one day was not significantly associated with shedding status on the next day, whether looking at specific days (Day 1 vs Day 2- OR: 1.6, 95% CI: 0.4,2.5; Day 2 vs Day 3- OR: 1.5, 95% CI: 0.2,1.8; Day 3 vs Day 4- OR:1.8, 95% CI: 0.6,4.0; Day 4 vs Day 5- OR: 1.6, 95% CI: 0.3,2.2) or averaged over the 5 day study period (OR: 1.5, 95% CI: 0.9,2.3). Overall, we found inconsistent and transient shedding patterns among all of our cohorts, which is similar to findings in past literature. Day 1 shedding status was the only variable consistently found to be associated with any subsequent shedding. Although Day 1 Shedders had a higher daily proportion of shedding throughout the entire study period than Day 1 Non-Shedders, these results were not statistically significant. Past literature has said that shedding cycles likely last between two and six days, but we found that shedding status on one day was not associated with shedding status on the next day, whether looking at pair of days or averaged over the five-day period. The inconsistency in our results calls in to question whether shedding patterns are truly transient acts or whether the sampling methods used potentially misclassify Shedders as Non-Shedders.Item Open Access Low-cost devices for occupational and environmental exposure assessment(Colorado State University. Libraries, 2018) Quinn, Casey, author; Volckens, John, advisor; Henry, Charles, advisor; Magzamen, Sheryl, committee member; Anderson, Georgiana Brooke, committee member; Reynolds, Stephen, committee memberThe measurement of chemical and physical stressors in occupational and environmental settings traditionally requires sophisticated equipment, trained professionals, and laboratory-based analyses. These requirements are cost and time prohibitive and, thus, limit the quantity and frequency of exposure monitoring. This dissertation focuses on the development of low-cost monitoring tools for evaluation of air and water quality. Water Quality Assessment Metal contamination of natural and drinking water systems poses hazards to public and environmental health. Quantifying metal concentrations in water typically requires sample collection in the field followed by expensive laboratory analysis that can take days to weeks to obtain results. The first portion of this was to develop a low-cost, field-deployable method to quantify trace levels of copper in drinking water by coupling solid-phase extraction/preconcentration with a microfluidic paper-based analytical device. This method has the advantages of being hand-powered (instrument-free) and using a simple 'read by eye' quantification motif (based on color distance). Tap water samples collected across Fort Collins, CO were tested with this method and validated against ICP-MS. We demonstrate the ability to quantify the copper content of tap-water within 30% of a reference technique at levels ranging from 20 to 500,000 ppb. The application of this technology, which should be sufficient as a rapid screening tool, can lead to faster, more cost-effective detection of soluble metals in water systems. Air Quality Assessment Personal monitors for air quality are expensive and cumbersome, which hinders epidemiologic and occupational exposure assessments. The Automated Microenvironmental Aerosol Sampler (AMAS) is a low-cost, wearable device containing four filter-pump assemblies designed to measure personal exposure particulate matter air pollution. This novel device collects size-selective samples of particulate matter from within distinct personal microenvironments (i.e. at home, at work, and in transit). The AMAS uses on-board sensors (GPS, light intensity, temperature, pressure, and acceleration) coupled with an algorithm (developed and described in to this work) to determine when an individual enters a given microenvironment and then initiates sampling through one of three filter assemblies. Low-cost devices capable of in-field quantification of pollutant hazards can allow researchers to afford more monitoring and analysis equipment and increase the size of epidemiology and industrial hygiene cohorts.Item Open Access Occupational exposure to bioaerosols at Colorado dairies(Colorado State University. Libraries, 2023) Craig, Amanda, author; Brazile, William, advisor; Reynolds, Stephen, committee member; Clark, Maggie, committee member; Ellis, Bob, committee member; Autenrieth, Dan, committee memberThe dairy industry is vital to the American economy and impacts both the general population and the workers immediately involved in dairy production. The United States is a significant contributor to the global industry producing approximately 14.6% of the global milk supply. To accomplish this, large herd dairy operations (>1000 head of cattle) operate 24 hours a day, 365 days a year. The long production hours and large herd size result in an increase in the number of injuries and illness in dairy workers. One type of illness diagnosed in dairy farmers is respiratory disease. Multiple researchers have shown that some workers in modern dairy operations have pulmonary function cross-shift declines and lower pulmonary function as well as increased rates of obstructive respiratory conditions such as chronic bronchitis, organic dust toxicity syndrome, occupational asthma, chronic obstructive pulmonary disease, and hypersensitivity pneumonitis (Reynolds, Lundqvist et al. 2013, Reynolds, Nonnenmann et al. 2013).Respiratory disease is caused by exposure to bioaerosols that consist of bacteria, fungi (and the corresponding constituents), pollen, animal dander, feed, and manure. Although bioaerosol exposure can cause infection, the immunological response the body has to bioaerosols that result in decreased lung function is more prevalent in dairy workers. Although some researchers have examined culturable bacteria and fungi, the viable organisms only represent a small fraction of what is detected in the air at the dairies (Katja Radon and Jörg Hartung 2002). One method used to identify Gram-negative bacteria is the recombinant factor C (rFC) assay, a rapid diagnostic assay to identify concentrations of endotoxins present in dairy environments. While endotoxins have explained a portion of the respiratory problems in dairy workers, they do not explain all of the respiratory diseases (May, Romberger et al. 2012). Little research has been performed to determine concentrations of fungi at dairies. Some work has been done using GC/MS to identify fungal markers, but the current research is the first study to use the rapid diagnostic (Glucatell) assay to quantify worker exposure to fungi at dairies. The primary goal of this study was to better characterize dairy worker exposure to bioaerosols through two sample analysis techniques: next generation sequencing (NGS) and rapid diagnostic assays (rFC and Gluactell). The specific aims of this dissertation were to 1) identify similarities and differences in bacterial communities between button samplers and biosamplers co-located inside a cattle pen, 2) characterize worker exposure to the microbial community on dairy farms in comparison to environmental sources, and 3) characterize worker exposure to two bioaerosols constituents based on dairy worker task. For Specific Aim 1, area air samples were taken for five consecutive days to compare the button and biosamplers co-located inside a fresh cow pen and then analyzed using NGS to determine the identity and quantity of bacteria. The current study was the first to compare the biosamplers and button samplers for NGS analysis at a dairy. The results from this study will help researchers make better decisions on the type of sampler that should be employed for collecting airborne bacteria. The researchers found that the biosampler was more effective at collecting samples for NGS. The two samplers had significantly different microbial communities that were identified based on the Principle Coordinate Analysis (PCoA) plot. However, upon further analysis the alpha diversity plot showed relatively similar Shannon and Inverse Simpson indices suggesting both samplers were sampling from the same core microbiome. Therefore, the difference between the samplers is likely due to the high variance in the samples and not actual differences in the microbial community. The alpha diversity plot also had a high operational taxonomic units (OTU) count indicating that the dairy microbiome has a high count of rare bacteria and a low count of dominant bacteria. The biosampler had a higher relative abundance of bacteria across all five sampling days. The majority of the top identified bacteria were Gram-positive. Currently, little research has been done to assess the impact of Gram-positive bacteria on worker respiratory health. Based on these results, future research should focus on Gram-positive bacteria as they may substantially contribute to respiratory disease. Some of the identified bacterial genera have potentially pathogenic species, but data on the species level is needed to determine the potential for infection. Both viable and non-viable bacteria and their corresponding constituents can act as inflammagens, potentially causing cross-shift lung function decline and respiratory disease (May, Romberger et al. 2012). Both samplers collected bacterial communities that could be analyzed and used for NGS, but the biosampler was identified as the better sampler because of the higher OTU counts and greater bacterial diversity. However, depending on the type of sample information required, the button sampler may be advantageous because it can be used for personal samples and throughout the entire day. For Specific Aim 2, personal and area air, hand swabs, and soil samples were collected at one dairy for five consecutive days and analyzed using NGS. The sample sets were then compared to identify differences and similarities between the sample type, identity of the bacteria, and potential for worker exposure. The difference between sampler (button vs biosamplers) was significantly different. The sample type explained more than 50% of the differences seen in the microbial community. The biosampler compared to the button sampler had a lot of variation within their respective types which could explain some of the differences between the communities due to the differences in sampling length and time of day. The variation in the biosampler was mainly due to the second sample taken on each day. The area air samples had the highest relative abundance between the sample types. Soil was thought to have the highest relative abundance but because the number of samples were biased toward air samples (n=60 vs n=15) when the most prevalent top bacteria were chosen they were driven by the air samples. The majority of the bacteria were also found to be Gram-positive across all the samples. The most common source of the bacteria based on the genera information was soil which was expected based on the dusty nature of the dairy environment. Some genera identified have potential pathogenic species, but this dataset did not provide information on the species level. No conclusions can be made on the possibility of infection from the bacteria in these samples. For Specific Aim 3, four dairies were recruited to assess airborne concentrations of Gram-negative bacteria, fungi and dust. Workers were binned into eight different tasks, and the task samples were compared to identify differences in exposure between the tasks. Differences in site and season were not statistically significant and were not included in subsequent analyses. The concentration of dust over a full work shift ranged from 0.95-5.6 mg/m3 and were lower than expected. The highest dust concentration was below the Occupational Safety Health Administration Permissible Exposure Limit (OSHA PEL) of 10 mg/m3 but was not below the suggested Occupational Exposure Limit (OEL) from the American Conference of Governmental Industrial Hygienists (ACGIH) of 2.4 mg/m3 indicating that dust exposure may be a concern for some of the tasks. Machine operators and milkers had the highest geometric mean dust concentrations with concentrations of 0.356 and 0.305 mg/m3 respectively. The endotoxin concentrations ranged from 0.078-40 EU/m3 which was lower than other research observing endotoxins concentrations at dairies and below the suggested OEL of 90 EU/m3. Multi-task workers and milkers had the highest endotoxin concentrations (Donham 2000). The β-glucan concentrations ranged from 0.2-212 pg/m3 with the highest task concentrations found in multi-task workers and machine operators. There is not a suggested OEL for β-glucans but concentrations measured in this study were higher than other studies in waste processing facilities (Douwes 2005). Ultimately, there was not one task that was consistently higher between the different exposure variables and there were no significant differences between any of the tasks. No conclusions or recommendations could be made on the task-based exposures at the dairies. However, even at low concentrations, exposure to agricultural dusts have been shown to induce responses from cytokines (Poole, Dooley et al. 2010). The genetic polymorphism TLR4 has also been demonstrated to cause workers to be more predisposed to sensitization to endotoxins at extremely low concentrations (Reynolds 2012).Item Open Access Personal, spatiotemporal exposure assessment: method development and application(Colorado State University. Libraries, 2013) Adams, Colby D., author; Volckens, John, advisor; Reynolds, Stephen, committee member; Peel, Jennifer, committee member; Brazile, William, committee member; Laituri, Melinda, committee memberTo view the abstract, please see the full text of the document.Item Open Access Social ecological determinants of occupational zoonotic disease exposure on Colorado dairy farms(Colorado State University. Libraries, 2019) Palomares Velosa, Jairo Enrique, author; Salman, Mo D., advisor; Roman-Muniz, Ivette N., advisor; Rao, Sangeeta, committee member; McConnel, Craig, committee member; Reynolds, Stephen, committee memberThe presence of zoonotic pathogens in dairy farms is a known risk for people that work and live in these settings. People who work or live on a farm, farm visitors, service providers, and veterinarians are the most at risks of zoonotic infections. Dairy cattle operations represent a working environment with a high risk of exposure to zoonotic pathogens. The prevention of zoonotic diseases in animal-human interfaces can be challenging. Due to the complexity of the social ecological system, and it requires comprehensive, integrative, and culturally compelling interventions. It has been demonstrated that the behavior of the person at risk can affect their exposure to infectious agents. As demonstrated in other settings, the implementation of consistent and robust preventive measures can change the behavior of persons at risk and success-fully decrease exposure to risk factors. One of the host factors that affect exposure to human infectious diseases is the behavior of the people at risk. The SEM is a theory-based framework that has been used to scientifically explore the complex and interactive personal and environmental factors that affect people's preventive behaviors in specific settings. In general, the aim of epidemiological studies on infectious diseases using the SEM framework is to inform the development or improvement of comprehensive and compelling intervention strategies that directly target the behavior change process at different levels of influence. In this research, we conducted several research activities using the Social Ecological Model (SEM) approach to expand our understanding of host and environmental factors that affect the exposure of zoonotic diseases as work hazards. In the first research chapter (chapter 2) we proposed an SEM with potential factors affecting the preventive behavior of people at risk of zoonotic diseases in dairy farms. In the next chapter, we use this model to build an instrument that measures SE factors for workers of dairy farms and provide sources of validity for that instrument. And in the last research chapter (chapter 4), we identify that self-efficacy and negative workplace perceptions are risk factors of Salmonella Dublin exposure (OR=1.43 [CI 1.11-2.22] & 1.22 [CI 1.02-1.53] respectively) and that knowledge and positive management perceptions were protective factors (OR = 0.90 [CI 0.79-1.00] & 0.91 [CI 0.82-1.00] respectively). Perception of supervisors and coworkers is a protective factor of Campylobacter exposure (OR=0.89 [CI 0.79-0.98]). Based on our observations, a supporting organizational environment, with supervisors and coworkers as deliverers of accurate safety information, and with increased knowledge and understanding of the potential risks and consequences of zoonotic diseases would help to reduce the occupational exposure of zoonotic disease in these farms.