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Theses and Dissertations

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Browsing Theses and Dissertations by Author "Abdo, Zaid, committee member"

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    Assessment and intervention strategies for agricultural inhalation exposures in occupational and community environments
    (Colorado State University. Libraries, 2024) Erlandson, Grant, author; Schaeffer, Joshua, advisor; Magzamen, Sheryl, committee member; Abdo, Zaid, committee member; Martenies, Sheena, committee member
    Agriculture represents an industry vital to the U.S. economy, supplying the public with nutritious food and providing millions of workers with employment. Also characterized as one of the most hazardous industries for workers, agricultural environments contain a variety of inhalation hazards capable of impacting the health of workers and adjacent community residents. Agricultural inhalation hazards include airborne organic and inorganic dusts; livestock associated gases, pesticides, bacteria, viruses, and antibiotics. This study will focus on (1) bioaerosol exposures in dairy operations and (2) inorganic dust pesticide exposures from agricultural applications. In dairy environments, workers are regularly exposed to high levels of organic dust (bioaerosols) and their inflammatory constituents (e.g., endotoxin, muramic acid, and β-glucans). Dairy bioaerosol exposure is associated with increased prevalence of respiratory disease (e.g., asthma, rhinitis, and chronic obstructive pulmonary disease) in dairy workers. While bioaerosol exposure in dairy environments has been well characterized in previous research, efforts to identify hygienic interventions that control exposure remain unsuccessful. In crop production agriculture, it is well documented that workers are exposed to high levels of pesticides associated with adverse health outcomes (e.g., respiratory and neurologic diseases). Further, in agricultural adjacent community environments, where lower chronic pesticide exposures are found, there is mounting evidence linking adverse health effects (e.g., adult and iii childhood cancers, neurologic and respiratory diseases, and birth outcomes) in residents to exposure from agricultural pesticide applications. However, weak and sometimes inconsistent associations previously reported highlight the limitations of current community exposure assessment techniques used for pesticides. For specific Aim 1, we pilot tested a novel low-cost nasal rinse intervention to modulate airway inflammation in ten bioaerosol exposed dairy workers. Dairy workers were randomly split into treatment (n = 5) and control (n = 5) groups and administered saline nasal rinses before and after their shift for five consecutive days. Treatment group participants received pre-shift hypertonic saline rinses while the control group received normotonic saline rinses. Both received normotonic rinses post-shift. Pro and anti-inflammatory cytokines were measured from recovered saline rinses. Linear mixed model results indicated treatment group participants experienced significantly higher concentrations of anti- (IL-10) and pro-inflammatory cytokines (IL-6 and IL-8) than the control group (p < 0.02, p <0.04, and p < 0.01 respectively). This study demonstrates the capacity of hypertonic saline nasal rinses to successfully upregulate anti-inflammatory cytokine production. However, conflicting upregulation of pro-inflammatory markers cloud interpretations of efficacy. For Aim 2, we further evaluated the immunomodulatory effects of hypertonic saline rinses vs. normotonic saline rinses longitudinally (2-5 shifts) in 45 bioaerosol exposed dairy workers. However, in this aim, treatment group participants received hypertonic rinses pre- and post-shift and 16S sequencing was added to analyses to capture potential washout effects on microbial diversity. No significant differences were observed between group or day for any of the measured markers or microbiome diversity metrics. Yet, non-significant increases in anti-inflammatory IL-10 concentrations across the study period were observed independent of iv treatment group suggesting the rinse itself may be more impactful than tonicity. This study provided mixed but encouraging results that justify further research on nasal rinses as an intervention in bioaerosol exposed dairy workers. For Aim 3, we evaluated the agreement between three exposure assessment techniques used to estimate residential organophosphate (OP) exposure in agricultural adjacent communities located in the Central Valley of California. OP exposure was estimated from household dust samples, California Pesticide Use Report (CPUR) pesticide use modeling, and urinary DAP metabolites across two sampling campaigns. Simple correlation tests revealed moderate correlations (ρs = 0.46) between household dust and use model exposure estimates. Estimates from urinary DAP metabolites exhibited low to no correlation with the other two estimates. Linear mixed model results also indicated no association between urinary DAP metabolites and household dust or use model estimates. This study illustrates a lack of agreement between community pesticide exposure assessment techniques regularly used in research and motivates the development of more robust assessment techniques.
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    Pathogens, pulmonary function, and the nasal microbiome of dairy workers
    (Colorado State University. Libraries, 2024) Seidel, James, author; Schaeffer, Joshua, advisor; Magzamen, Sheryl, committee member; Abdo, Zaid, committee member; Valley, Morgan, committee member
    Dairy workers are exposed to bioaerosols that are diverse in both size (0-100 µm in aerodynamic diameter) and inflammatory constituents (e.g. endotoxins, muramic acid, and β-glucans). Bioaerosol exposure at dairies is associated with a higher prevalence of chronic obstructive pulmonary disease (COPD), chronic bronchitis, asthma, respiratory pneumonitis, and asthma-like reductions in pulmonary function. More recently, opportunistic pathogens present at dairies such as the novel influenza D virus (IDV), influenza A (IAV), and livestock-associated Methicillin-resistant Staphylococcus aureus (MRSA) have also been a focus of research, as these pathogens can infect workers and pose a public health risk through community spread. Intrinsic factors such as genetics and childhood exposures likely play a major role in exposure response and respiratory disease pathology, but little research has been focused on the nasal microbiome's role in pathogen exposure and cross-shift changes of pulmonary function. From a longitudinal (2-5 working shifts) cohort of dairy workers in the High Plains Region of the US, this research analyzed pathogens found in the nares of dairy workers via pre- and post-shift nasal lavages. The same nasal lavages underwent targeted 16S rRNA gene sequencing to quantify the bacterial communities that comprise the nasal microbiome. Spirometry was also performed on dairy workers pre- and post-shift to measure cross-shift changes in pulmonary function. Overall, 32.1% (n=237) of nasal lavages tested positive for Methicillin-susceptible Staphylococcus aureus (MSSA), 11.4% tested positive for MRSA, 17.3% for IDV, 2.5% for IAV, and 1.3% for influenzas C virus (ICV). Only 1 of the original 31 participants never tested positive for a pathogen during their workweek. Differences in nasal microbiome characteristics emerged based on pathogen positivity, and differential abundance analysis revealed significant differences in genera based on the positivity of both bacterial and viral pathogens. The dairy workers in this study also experienced decreases in cross-shift pulmonary function. The average decrease in forced expiratory volume in one second (FEV1) over 108 working shift was -74.4 ml, and the average decrease of forced vital capacity (FVC) was -92.5 ml. Significant differences in microbiome characteristics did emerge based on post-shift and cross-shift spirometry performances, and taxonomic differences were noted in participants performing poorly on cross-shift FVC. The nasal microbiomes of workers also underwent community state typing, and participants in CST3 showed the most resilience to cross-shift changes in lung function. This research also investigated the efficacy of a hypertonic saline nasal lavage in improving cross-shift changes in pulmonary function. From a cohort of 44 dairy workers, 22 workers received pre- and post-shift hypertonic saline nasal lavages with an osmotic concentration of 400 milliosmole (mOsm). The 22 participants in the control group received pre- and post-shift normotonic saline (308 mOsm) nasal lavages. Based on constructed mixed linear models, the treatment improved cross-shift outcomes of the forced expiratory flow at 25-75% of the vital capacity (FEF25-75%), but had little effect on FEV1 and FVC. The use of a pre- and post-shift lavage of any osmolarity, however, appeared to reduce the burden of cross-shift pulmonary function decline often experienced by dairy workers. For the first time, this research showed that both viral and bacterial pathogens are present in the nares of US dairy workers. This work also identified the nasal microbiome characteristics that may play a role in pathogen exposure and cross-shift lung function outcomes. The use of a saline nasal lavage as an intervention was also explored, and the intervention appeared to improve cross-shift pulmonary function outcomes.