Global, Environmental, and Occupational Health Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/10071
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Item COUPLING DNA LABELING AND NEXT-GENERATION SEQUENCING TECHNIQUES TO CHARACTERIZE METABOLICALLY-ACTIVE BACTERIA IN NONTRADITIONAL IRRIGATION WATER(2019) Malayil, Leena; Sapkota, Amy R; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bacteria are ubiquitous in irrigation water resources and can include pathogens that may compromise food safety and public health. However, only a small fraction of total bacterial community members in water can be identified through standard culture-based laboratory methods. 16S rRNA and shotgun sequencing techniques have improved the identification of non-culturable bacteria in water resources. Nevertheless, because sequencing approaches are nucleic-acid based, they are unable to differentiate between the proportion of bacterial communities identified that are live and metabolically-active versus those that are represented by free, relic DNA, not present in viable cells. To bridge this knowledge gap, my dissertation research coupled DNA-labeling (using 5-bromo-2’- deoxyuridine (BrdU) and propidium monazide (PMA)) with next-generation sequencing approaches to identify and comprehensively characterize metabolically-active bacteria in multiple nontraditional irrigation water sources in the Mid-Atlantic region. My aims were as follows: 1) To characterize the metabolically-active fraction of bacterial communities, as well as antibiotic resistance genes and virulence gene profiles in nontraditional irrigation water sources; 2) To evaluate culture-dependent and -independent methods in the detection of metabolically-active pathogenic and non-pathogenic Vibrio species in four nontraditional irrigational water sources; and 3) To track metabolically-active bacterial communities from rooftop-harvested rainwater to irrigated produce in Maryland. Overall, we identified diverse metabolically-active bacterial communities in all nontraditional water sources. Notably, we observed the presence of viable bacteria of importance to both human and/or animal health (Actinobacterium spp., Flavobacterium spp., Aeromonas spp. Pseudomonas spp. and Vibrio spp.). Interestingly, diverse antimicrobial resistance and virulence genes were predominantly found in non-BrdU-treated samples, indicating that these genes can persist in relic DNA and could be transferred to other environmental bacteria through transformation events. We also source-tracked viable bacteria, including Sphingomonas spp., Enterobacter spp., Enterococcus spp, and Citrobacter spp. from rooftop-harvested irrigation water to produce. In summary, this work provides the first description of total, viable, and metabolically-active bacterial communities in different nontraditional irrigation water sources. These data can be used to improve risk characterization of these water sources, and ultimately inform the selection of appropriate cost-effective remediation methods to treat these waters prior to irrigation activities in order to prevent foodborne outbreaks.Item WATER REUSE FOR FOOD PRODUCTION IN THE WEST BANK AND ISRAEL: ASSESSING THE EFFICACY OF HOUSEHOLD GREYWATER TREATMENT SYSTEMS, AND CONSUMER PERCEPTIONS OF REUSE APPLICATIONS(2019) Craddock, Hillary Anne; Sapkota, Amy R; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Greywater is increasingly reused for agricultural irrigation in the Middle East. However, there is a dearth of data regarding antibiotics, herbicides, and antibiotic-resistant bacteria in household greywater reuse systems. Additionally, there are minimal data assessing consumer perceptions of water reuse practices. To address these gaps, my dissertation aims were to: 1) evaluate the presence of antibiotics and herbicides in greywater and treated effluent; 2) assess the prevalence of antibiotic-resistant Enterobacteriaceae in greywater and treated effluent; and 3) explore consumer perceptions of water reuse practices in Israel and the West Bank. For Aims 1 and 2, household greywater (n=23), treated effluent (n=23) and pond water (n=12) were collected from four farms in the West Bank from October 2017 to June 2018. The presence of antibiotics and herbicides was quantified using high performance liquid chromatography-tandem mass spectrometry, E. coli were enumerated via membrane filtration, and isolates were tested for antimicrobial susceptibility using microbroth dilution. For Aim 3, surveys (n=236) were administered in Eilat, Israel and Bethlehem, West Bank. Statistical analysis included ANOVA, chi-squared, and Fisher’s exact tests. Multiple antibiotics and herbicides were detected in greywater influent. Removal during treatment was variable across compounds. The majority of influent (76.5%) and effluent (70.6%) samples had detectable levels of E. coli. Resistance was most commonly observed against ampicillin, trimethoprim-sulfamethoxazole, tetracycline, and cefazolin. Regarding consumer perceptions, >50% of Israeli respondents were willing to serve raw and cooked produce irrigated with reused water. Palestinian respondents were more willing to engage in high-contact uses than Israeli respondents. The successful completion of this research has advanced knowledge regarding 1) the persistence of chemical and microbiological contaminants in treated household greywater that is used for food crop irrigation; and 2) consumer acceptance of water reuse practices. Farmers in the West Bank and around the world are combating decreasing quality and quantity of water and will increasingly rely on consumers willing to purchase produce irrigated with treated wastewater. Future work must ensure that farmers have access to safe and abundant irrigation water, and that consumers can be confident that they are purchasing safe food.Item Exposure to Ambient Air Pollution and Correlates of Cardiovascular Disease among Youth with Type 1 Diabetes(2019) Montresor-Lopez, Jessica Anne; Puett, Robin C; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Air pollution from traffic-related sources is associated with cardiovascular disease (CVD), potentially through changes in systemic inflammatory responses, vascular function and oxidative stress leading to atherosclerosis, thrombosis or endothelial dysfunction. Individuals with type 1 diabetes (T1D) have a greater risk of CVD-related morbidity and mortality than the general population, and they may be more susceptible to the effects of air pollution on CVD. Although these increased risks begin during childhood, very few studies have assessed the impact of air pollution on children and youth with T1D. This dissertation directly addresses gaps in the epidemiologic evidence by: 1) evaluating the relationship of short-term exposures to traffic-related air pollutants with pulse wave velocity (PWV), a measure of arterial stiffness, 2) assessing the effects of changes in air pollution exposures on changes in inflammatory biomarkers, including C-reactive protein, fibrinogen and interleukin-6 (IL-6), and 3) examining the relationship of long-term exposures to traffic-related air pollution with allostatic load (AL), a measure of cumulative biological risk, among a cohort of youth with T1D. Data were obtained from the SEARCH for Diabetes in Youth (SEARCH) study. SEARCH was initiated in 2000 and includes a diverse population of US youth diagnosed with diabetes prior to age 20 years. Anthropometric and laboratory measures were taken at SEARCH study visits, and standardized questionnaires were used to collect information on important covariates. Air pollution exposures were estimated using spatio-temporal models and assigned to residential addresses for each participant. In the first study, we identified a significant association between increased exposure to PM2.5 on the day of the examination with higher PWV using generalized linear models adjusted for lifestyle and demographic characteristics. In the second analysis, we found consistent positive effects of increases in PM2.5 over the week prior to the examination with IL-6 using longitudinal mixed models. In the third study, no significant associations were observed for monthly and annual PM2.5 exposures or proximity to major roadways with AL in fully adjusted linear mixed models. However, effects differed by race/ethnicity and gender. Overall, this research indicates that youth with T1D may be at higher risk for air pollution-related cardiovascular impacts.Item The Impact of Private Drinking Water Wells and Animal Feeding Operations on the Incidence of Acute Gastroenteritis in Maryland: A Mixed Methods Approach(2019) Murray, Rianna Teresa Frederika; Wilson, Sacoby M; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)More than 44.5 million people in the United States (approximately 14% of the population) rely on private domestic wells as their primary source of drinking water. The water quality of private wells is not regulated at the state or federal level, leaving homeowners with wells responsible for the safety of their water. Meanwhile, each year, an estimated 48 million people in the U.S. are sickened, 128,000 are hospitalized, and 3,000 die of gastrointestinal (GI) illnesses caused by microorganisms that are typically transmitted through contaminated food. Given that the potential of private wells as a non-foodborne transmission pathway for these microorganisms is not well understood, my dissertation evaluated these relationships, as well as characterized the quality of private well water in Maryland. My objectives were to: 1.) Investigate the water quality of private wells in Maryland and the effect of animal feeding operations on this water quality using fecal indicator bacteria; 2.) Investigate associations between the prevalence of private wells and the incidence of campylobacteriosis in Maryland at the zip code level using data from the FoodNet active surveillance System; and 3.) Investigate associations between the prevalence of private wells and the incidence of salmonellosis in Maryland at the zip code level using FoodNet data. My findings demonstrated that 43.2% of private wells tested in Maryland did not meet at least one federal health-based drinking water standard. Additionally, my data showed that the prevalence of private wells in Maryland is a risk factor for the incidence of campylobacteriosis and salmonellosis in the coastal counties of the state. The presence of broiler chicken operations in a zip code is also a risk factor for campylobacteriosis and salmonellosis in coastal counties. These findings provide evidence for the strengthening of private well water regulations and for improving education and outreach to private well owners on proper maintenance and testing for their wells.Item Antimicrobial Resistance of Enterococci in Surface and Recycled Water in the Mid-Atlantic(2018) Patterson, Rebecca; Micallef, Shirley A; Payne-Sturges, Devon C; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Increasing demands for agricultural water require identification of alternative water sources. Enterococcus species can exhibit antimicrobial resistance and transfer resistance traits to other bacterial taxa, including human pathogens. This study evaluated the distribution and antimicrobial resistance of Enterococcus faecalis and E. faecium in surface and recycled waters. In all, 365 isolates from 129 water samples collected over one year were identified by species, and 95 were selected for antimicrobial susceptibility testing. Season, water type, temperature and salinity were statistically significantly associated with species probability, and season with antimicrobial resistance of E. faecalis. 1.3% of E. faecalis and 5.0% E. faecium were pan-susceptible but 100% were susceptible to ampicillin, vancomycin, daptomycin and linezolid. Multidrug resistance was detected in 16% of E. faecalis and 70% of E. faecium isolates. Enterococcus was ubiquitous in water and exhibited resistance to multiple antimicrobials, but resistance to antimicrobials of last resort for enterococcal infections was non-existent.Item AIR QUALITY ASSESSMENT OF RESIDENTIAL EXPOSURE TO PARTICULATE MATTER AND VOLATILE ORGANIC COMPOUNDS NEAR A CONCRETE BLOCK PLANT AND TRAFFIC IN BLADENSBURG, MARYLAND(2018) Ezeugoh, Rosemary Ifeoma; Wilson, Sacoby M; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Ambient air pollution from stationary sources, industrial traffic, and commuter traffic can negatively impact air quality and human health. Ernest Maier, a concrete block plant located in Bladensburg, Maryland wants to expand to include a concrete batching plant on the same property. This expansion could further degrade air quality and impact the health of vulnerable residents. Air quality monitoring were conducted in the community at five personal sites using the Airbeam and Atmotube, which are wearable, real-time sensors that can measure PM2.5 and VOCs respectively. Sampling and traffic counts were conducted in thirty minutes’ periods to capture morning on-peak, afternoon off-peak and evening on-peak periods. Pearson’s correlation revealed that a weak correlation among the PM2.5 and VOC concentrations observed between the different sites and some of the values were found to be statistically significant. ANOVA analysis showed that the PM2.5 levels were significantly different at the different sites (p-value 0.001).Item NEW METHODOLOGY TO IDENTIFY POTENTIAL ENVIRONMENTAL TRIGGERS FOR ANCA-ASSOCIATED VASCULITIDES(2018) Beins, Kaley Elizabeth; Milton, Donald K.; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A series of rare autoimmune disorders that affect the blood vessels, vasculitis is chronic and potentially deadly. Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) comprise three diagnostic forms of this autoimmune disorder: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA or Churg-Strauss syndrome). The limited resources available to vasculitis researchers have been mostly targeted toward treatment and relapse prediction with a small amount of research examining genetic and environmental etiologic factors. Therefore, additional research is needed to understand the role of gene-environment interactions in AAV etiology. This thesis reviews the current body of AAV literature with a focus on candidate genes, occupational and environmental exposures, and the hygiene hypothesis. It also designs an original survey and study methodology to further investigate these etiologic factors. A better understanding of AAV etiology will lead to prevention and improved treatment of these costly diseases.Item THE DEVELOPMENT OF A COMMUNITY INFORMED CUMULATIVE STRESSORS AND RESILIENCY INDEX (CSRI) TO EXAMINE ENVIRONMENTAL HEALTH DISPARITIES AND DISEASE RISK IN SOUTH CAROLINA(2017) Naney, Kristen Burwell; Wilson, Sacoby M; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Communities with environmental justice (EJ) issues usually have disparities in exposure to chemical and non-chemical stressors and health status compared to other communities without underlying EJ issues. Improving cumulative risk assessment (CRA) screening tools and models can provide the necessary information needed to reduce health disparities and create more resilient communities. To address these gaps in EJ science, this dissertation has three specific aims: 1) Identify perceptions of environmental and resilience factors that may influence health among African-Americans in North Charleston, South Carolina (SC) (Study 1), 2) Develop a Cumulative Stressors and Resiliency Index (CSRI) used to rank risk in SC (Study 2), and 3) Examine associations between CSRI scores and risk of asthma hospitalizations/emergency department (ED) visits in SC (Study 3). Community stakeholders (N=18) participated in key-informant interviews and completed a 26-item paper survey in study one. Interviews were transcribed and coded, while mode, frequencies, and percentages were calculated for each indicator based on its ability to influence health. Statistical tests performed in study two included a Principal Component Analysis (PCA), one-way analysis of variance (ANOVA), and linear regression performed in SAS Enterprise Guide 7.1. Choropleth maps were also developed in ArcMap 10.5. We concluded by calculating descriptive statistics by Environmental Affairs (EA) region, Spearman’s rank-order correlation, one-way ANOVA, and negative binomial regression analyses in study three. Many of the indicators (61%) were rated as extremely high priority items and included environmental hazards, sociodemographic attributes, and factors that may influence resiliency. CSRI scores ranged from 7.4 – 64.0 with a mean score of 29.1. Statistically significant differences in CSRI scores were evident by EA region (p <0.0001) and a one-unit increase in the percentage of non-white populations per census tract projected to increase CSRI scores by roughly 6.1%. The CSRI was not able to predict risk of asthma hospitalizations/ED visits as hypothesized. Overall, we demonstrated that identifying and addressing chemical and non-chemical stressors and resiliency gaps in areas impacted by environmental injustice may lead to overall improvements in community resilience. We anticipate this work will be used as a blueprint to build more resilient and equitable communities in SC.Item Assessment of Zero-Valent Iron Capabilities to Reduce Food-borne Pathogens via Filtration and Residual Activities in Irrigation Water(2017) Bradshaw, Rhodel; Sapkota, Ph.D., Amy R; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Inadequate disinfection of contaminated freshwater that is used to irrigate food crops that are eaten raw can result in foodborne illnesses. Therefore, in this study we assessed the efficacy of a low-cost, water treatment technology, zero-valent iron (ZVI), in reducing microbiological contamination of synthetic irrigation water. Specifically, we compared the capabilities of a ZVI-sand filter versus a sand filter in reducing levels of Salmonella Newport MDD314 and E. coli TVS 353 through filtration or residual disinfection. Our data showed that ZVI-sand filtration was more effective than sand filtration alone in reducing levels of both of these microorganisms. Our results also showed that, after filtration, there seemed to be no residual disinfection capabilities associated with either the ZVI-sand system or the sand system alone. Our findings suggest that ZVI-sand filtration can effectively reduce microbial contaminants in irrigation water; however, there seem to be no residual disinfection capabilities after filtration.Item A pilot comparison of first morning versus 24-hour urinary deoxynivalenol in UK adults(2017) Boonchaisri, Natalie; Turner, Paul; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Using unpublished data from an original study by Turner et al. (2010a), the relationship between first morning void (FMV) and 24-hour urine collections was examined in UK adults to determine if FMV collections provide a reasonable estimate of DON intake compared to 24-hour collections. The intraclass correlation coefficient (ICC) was computed to evaluate variability in DON concentrations and generalized estimating equation (GEE) models were used to assess the relationship between collection types. Greater between-person variability was observed in 24-hour collections, unadjusted and adjusted for creatinine (ICC=0.78 and 0.56, respectively). GEE models suggest urinary DON concentrations in FMV collections were strongly correlated with 24-hour collections (r=0.78, p<0.0001), meaning FMV collections may provide just as reasonable an estimate of DON intake compared to 24-hour collections when adjusting for age, sex, and BMI. These results strengthen the methodology behind exposure biomarkers and urinary assays when estimating DON intake.
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