Global, Environmental, and Occupational Health Theses and Dissertations

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    EXAMINATION OF THE ASSOCIATIONS BETWEEN SELECTED PERFLUOROALKYL SUBSTANCES AND THEIR ISOMERS WITH BODY WEIGHT IN ADOLESCENTS USING NHANES 2013-2018
    (2023) Snyder, Jessica A; Payne-Sturges, Devon; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    0ABSTRACT Title of thesis: EXAMINATION OF THE ASSOCIATIONS BETWEEN SELECTED PERFLUOROALKYL SUBSTANCES AND THEIR ISOMERS WITH BODY WEIGHT IN ADOLESCENTS USING NHANES 2013-2018 Jessica Snyder, Master of Science, 2023 Thesis Directed by: Professor Devon Payne-Sturges Maryland Institute for Applied Environmental Health Perfluoroalkyl substances (PFAS), a class of environmentally persistent chemicals, are suspected of having obesogenic properties, with studies thus far being inconclusive. Few past studies of PFAS toxicity have distinguished between isomer types of each PFAS group during analysis, however. In this thesis, data for non-smoking 14-19 year-olds from three cycles of the National Health and Nutrition Examination Survey was analyzed to identify potential associations in adolescents between bodyweight and two major families of PFAS: perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) and to additionally determine if differentiating between linear and branched isomeric groups of two major PFAS families could better elucidate any associations found. In unadjusted models, weighted linear regression of body mass index (BMI) and serum concentrations of branched, linear, and total PFAS isomer groups, all returned positive associations ranging from β (95% confidence interval) of 4.06 (3.44, 4.68) for total PFOS to 12.33 (10.39,14.28) for linear PFOA. When models were adjusted for sex, age, race/ethnic origin and income level, however, only a negative association between BMI and branched PFOS (bPFOS) was found, with β= -1.24 (-2.10, -0.39). Unadjusted weighted logistic regression models of both overweight and obese status resulted in positive associations between obesity and both branched PFOS and total PFOS with odds ratios (95% confidence intervals) of 0.45 (0.27, 0.74) and 0.86 (0.75, 0.99) respectively. After adjusting for potential confounders, the only statistically significant relationship was between branched bPFOS and obesity, with a 56% decrease in the odds of obesity for every unit increase in serum concentration of bPFOS [β =-1.06, adjusted odds ratio= 0.44 (0.26,0.76)]. There was no significant difference between the sexes in any results. The apparent protective effect that bPFOS has against obesity and elevated BMI, notable as a health outcome association in itself, also illustrates that isomeric differentiation is important in studying PFAS, as nPFOS had no statistically significant 1 association by itself while ΣPFOS, used by many studies, did. Thus, the lack of differentiation could mask which PFAS type contributes to any associations discovered.
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    CHARACTERIZING BACTERIAL COMMUNITIES ACROSS DIVERSE TOBACCO PRODUCTS AND DYSBIOSIS IN THE ORAL MICROBIOME RESULTING FROM TOBACCO USE
    (2022) Chattopadhyay, Suhana; Sapkota, Amy R; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    To evaluate the adverse health effects associated with tobacco smoking, the majority of studies have largely focused on the impact of chemical constituents in tobacco products and less on the impact of microbial contaminants within these products. Similarly, the United States (U.S.) Food and Drug Administration’s (FDA) Family Smoking Prevention and Tobacco Control Act (FSPTCA) requires tobacco manufacturers and importers to test and report on chemical constituents included on their list of harmful and potentially harmful constituents (HPHCs) in tobacco products and tobacco smoke; however, this HPHC list excludes microorganisms. Nevertheless, over the past decade, an increasing number of studies have explored the bacterial microbiome of tobacco products (e.g., cigarettes, little cigars, cigarillos, hookah and smokeless tobacco) and mainstream smoke. These studies have yielded robust data on bacterial diversity and bacterial community composition within individual tobacco product types. However, to date, there are no comparative characterizations of the bacterial microbiome across diverse tobacco products. In particular, there have been no studies that have characterized the metabolically-active (live) bacterial communities across these products; bacterial communities that might be transferred to the user’s oral cavity and cause subsequent adverse health effects. Furthermore, from an oral health perspective, while smoking/using tobacco products causes significant oral dysbiosis (bacterial community disturbances), there is a lack of data on the potential transfer of bacteria from tobacco products to user’s oral cavities or transient temporal changes in the oral microbiome that might result from smoking these tobacco products. Moreover, there are limited data comparing oral microbiome differences between cigarette smokers and smokeless tobacco users. To address these knowledge gaps, my dissertation research involved a comparative analysis of the bacterial microbiome of commercially-available tobacco products and anevaluation of the impacts of tobacco use on the oral microbiome of users. My specific aims were: 1) To evaluate the compositional differences in the bacterial microbiome between conventional tobacco products; 2) To evaluate transient changes in the oral microbiome of cigarette smokers after a single use of a little cigar; and 3) To conduct a comparative characterization of the oral microbiome between cigarette users, smokeless tobacco users, and non-users over time. Overall, I found that each type of conventional tobacco product harbored a significantly different bacterial community, with mentholation and/or flavoring being a significant driver of bacterial community changes. However, across all products the majority of the metabolically-active bacterial community was identified as Pseudomonas, along with members of the phylum Firmicutes, as well as a few pathogenic species previously associated with animal/human respiratory diseases. In analyzing the oral microbiome of cigarette smokers, I found that a singleuse of a little cigar product did not cause transient changes in the oral microbiome. In analyzing longer temporal effects of smoking on the oral microbiome, I found that, even though total bacterial diversity and composition did not change over time, multiple bacterial taxa were significantly different, with regard to their relative abundance, after four months. In addition, I found that dysbiosis of the oral microbiome was dependent on the type of tobacco product used (cigarettes or smokeless tobacco), and that tobacco smokers/users’ oral microbiomes harbored a more diverse set of bacterial species when compared to that of non-users. In summary, this work provides a comparative analysis of the total and metabolically-active bacterial microbiome of tobacco products, as well as rich findings regarding the relationship between tobacco use and oral microbiome dysbiosis. These data address major research priorities of the FDA relating to furthering our understanding of the adverse health risksassociated with tobacco smoking. Specifically, my data will add to the current body of knowledge regarding the potential role of tobacco bacterial communities in the development of smoking-related diseases. My data also can be leveraged by tobacco regulatory bodies to make future evidence-based policy changes that help reduce risks associated with microorganisms in tobacco products and protect public health.
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    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.
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    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.
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    IMPACT OF RURALITY, BROILER OPERATIONS, AND COMMUNITY SOCIOECONOMIC FACTORS ON THE RISK OF CAMPYLOBACTERIOSIS IN MARYLAND
    (2013) Zappe Pasturel, Barbara; Sapkota, Amy; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The combined impact of community-level environmental and socioeconomic factors on the risk of campylobacteriosis were evaluated. Campylobacter case data (2002-2010, n=3,694) were obtained from the Maryland Foodborne Diseases Active Surveillance Network. Community-level socioeconomic and environmental data were obtained from the 2000 U.S. Census and the 2007 U.S. Census of Agriculture. Data were linked by zip code. Incidence rate ratios were derived by Poisson regressions. A subset of zip code-level characteristics was mapped. In zip codes that were 100% rural, incidence rates of campylobacteriosis were 6 times (IRR=6.18; 95%CI=3.19-11.97) that of urban zip codes. In zip codes with broiler chicken operations, incidence rates were 1.45 times that of zip codes without broilers (IRR=1.45, 95%CI=1.34-1.58). Higher rates were also observed for zip codes that were predominantly white and had high median incomes. Findings suggest that the risk of campylobacteriosis could be significantly influenced by the community and environment where one lives.
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    An Assessment of Exposure to Pollution by Recreational Users of The Anacostia Watershed: Project Recreate
    (2013) Murray, Rianna Teresa; Wilson, Sacoby; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The Anacostia River, a tributary of the Chesapeake Bay, is highly contaminated with raw sewage, heavy metals, oil and grease, trash, pathogens, excessive sediments and organic chemicals. Many people use this river on a regular basis for recreational purposes, including kayaking, canoeing, rowing and sport fishing. The contaminants in the river potentially pose threats to human health for recreational users. While there has been some study of the exposure to subsistence fishers in this region there is currently little information available on the risks faced by recreational users. This work gathered pilot data on recreational users with the purpose of assessing any associated exposure risks to contaminants. The high levels of contamination in the Anacostia River and the popularity of recreation makes this an important public health issue. This study is the first to combine an evaluation of risk and risk perception for the recreational population of the Anacostia River.
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    Maternal mercury exposure, season of conception and adverse birth outcomes in an urban immigrant community in New York City
    (2012) Bashore, Cynthia Diana Jennings; Sapkota, Amir; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Adverse birth outcomes such as preterm birth (PTB: < 37 weeks gestation) and low birthweight (LBW: <2500g) result in severe infant morbidity and mortality. In the United States, there are racial and ethnic differences in the prevalence of preterm birth and low birth weight. The focus of this study is to examine the association between frequency of maternal fish consumption during pregnancy, prenatal mercury exposure, and season of conception with preterm birth and low birth weight in a population of African-American, Caribbean and West Indian women in an urban immigrant community in New York City. The proportion of preterm births and low birth rates in this cohort of women was higher than reported in other studies of African-American and Caribbean births in New York City. There was no association between maternal urinary mercury or infant cord blood concentrations and either LBW or preterm birth. Infants conceived in winter (December, January, February) were at increased odds of low birthweight.
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    Environmental Impacts on Fecal Indicator Bacteria in 5 National Park Recreational Water Areas
    (2012) Raspanti, Greg A.; Sapkota, Amir; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The National Park Service oversees 397 park units throughout the 50 states and US territories. Due to the high visitation, protecting the health of visitors is a top priority. Fecal contamination in recreational water can occur as a result of land use practices and weather related factors. The aim of this study is to investigate weather related factors and land use factors that contribute to fecal contamination in five National Park units. Overall, rainfall proved to be highly predictive of subsequent elevations in fecal bacteria. Specifically, same day rainfall and day prior to the sampling day rainfall showed the strongest association with elevated fecal bacteria levels. Seasonal variation of fecal bacteria was generally higher in the summer months. The land use variables were not highly predictive of fecal bacteria levels. The results of this study can be used by park managers to better predict variations in fecal contamination.