ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- All Subjects: public health
- Creators: Abbaszadegan, Morteza
Description
Monitoring human exposure to chemicals posing public health threats is critically important for risk management and for informing regulatory actions. Chemical threats result from both environmental pollutants and elected substance use (e.g., consumption of drugs, alcohol and tobacco). Measuring chemical occurrence and concentrations in environmental matrices can help to pinpoint human exposure routes. For instance, indoor dust, a sink of indoor environmental contaminants, can serve to assess indoor air contamination and associated human exposures. Urban wastewater arriving at treatment plants contains urine and stool from the general population, the analysis of which can provide information on chemical threats in the community and ongoing harmful exposures. Analysis of sewage sludge can serve to reveal the identity and quantity of persistent organic pollutants in cities and inform estimates of toxic body burdens in local populations.
The objective of this dissertation was to investigate the occurrence and quantity of select, potentially harmful, anthropogenic chemicals in various environmental matrices and to explore the diagnostic value of analytical assays for informing public health decision-making. This dissertation (i) is the first to report spatio-temporal variations and estrogenic burdens of five parabens in sewage sludge from at the U.S. nationwide scale; (ii) represents the first China-wide survey to assess the occurrence and toxic emissions of parabens, triclosan, triclocarban, as well as triclocarban metabolites and transformation products contained in Chinese sewage sludge; (iii) documents the first use of a dispersive solid phase extraction method for indoor dust to measure dust-borne parabens, triclosan and triclocarban and estimating associated human exposures from dust ingestion; and (iv) is the first U.S. study to assess population-level alcohol and nicotine consumption in three U.S. communities using wastewater-based epidemiology (WBE). Obtained data on baseline levels of selected emerging contaminants in sewage sludge and indoor dust can serve to inform the future monitoring needs, risk assessment, and policy making. This work showcases the utility of WBE and urban metabolism metrology via dust and sewage sludge analysis to assess human behavior (e.g., drinking and smoking) and exposure risks more rapidly, efficiently and anonymously than traditional approaches can.
The objective of this dissertation was to investigate the occurrence and quantity of select, potentially harmful, anthropogenic chemicals in various environmental matrices and to explore the diagnostic value of analytical assays for informing public health decision-making. This dissertation (i) is the first to report spatio-temporal variations and estrogenic burdens of five parabens in sewage sludge from at the U.S. nationwide scale; (ii) represents the first China-wide survey to assess the occurrence and toxic emissions of parabens, triclosan, triclocarban, as well as triclocarban metabolites and transformation products contained in Chinese sewage sludge; (iii) documents the first use of a dispersive solid phase extraction method for indoor dust to measure dust-borne parabens, triclosan and triclocarban and estimating associated human exposures from dust ingestion; and (iv) is the first U.S. study to assess population-level alcohol and nicotine consumption in three U.S. communities using wastewater-based epidemiology (WBE). Obtained data on baseline levels of selected emerging contaminants in sewage sludge and indoor dust can serve to inform the future monitoring needs, risk assessment, and policy making. This work showcases the utility of WBE and urban metabolism metrology via dust and sewage sludge analysis to assess human behavior (e.g., drinking and smoking) and exposure risks more rapidly, efficiently and anonymously than traditional approaches can.
ContributorsChen, Jing (Author) / Halden, Rolf U. (Thesis advisor) / Borges, Chad R (Committee member) / Abbaszadegan, Morteza (Committee member) / Arizona State University (Publisher)
Created2018
Description
This dissertation studies the larger issue of antibiotic resistance with respect to how antibiotics are being introduced into the environment, focusing on two major anthropogenic pathways: animal husbandry for human consumption, and the recycling of wastewater and municipal sludge generated during conventional biological sewage treatment.
For animal production on land (agriculture) antibiotics are often used for growth enhancement and increased feed efficiency. For animal production in water (aquaculture) antibiotics are often used as a prophylactic. I found that the same antibiotics are being used in both industries and that the same strains of human pathogens have also been isolated from both sources, expressing identical resistance mechanisms. In U.S. seafood, five out of 47 antibiotics screened for were detected at levels of 0.3 to 7.7 ng/g fresh weight. Although compliant with FDA regulations, the risk for resistance still exists, as even low antibiotic concentrations have been shown to exert selective pressure on bacteria.
Similarly low concentrations of antibiotics were found in U.S. biosolids at levels of 0.6 to 19.1 ng/g dry weight. Of the five antibiotics detected, two have never been reported before in biosolids. Three have never been reported before in U.S. biosolids. Using the raw numbers obtained from antibiotic screenings in biosolids, I assessed the impact of employing four different LC-MS/MS methods, concluding that analysts should experimentally determine the most appropriate quantitation method based on the analyte targeted, matrix investigated, and research goals pursued. Preferred quantitation approaches included the isotope dilution method with use of an analogous standard and, although time and resource demanding, the method of standard addition.
In conclusion, antibiotics introduced into the environment via agriculture, aquaculture, and wastewater recycling pose a combination of chemical and biological threats. Aside from exerting outright chemical toxicity to non-target organisms, antibiotic residues can promote the development of multi-drug resistance in human pathogens. Public health protection approaches to stem the risks posed by animal husbandry may include reserving drugs for exclusive, human use, decreasing their usage altogether, improving reporting efforts, reevaluating existing regulations on agricultural and aquacultural antibiotic usage, and improved risk assessment for biosolids application on land.
For animal production on land (agriculture) antibiotics are often used for growth enhancement and increased feed efficiency. For animal production in water (aquaculture) antibiotics are often used as a prophylactic. I found that the same antibiotics are being used in both industries and that the same strains of human pathogens have also been isolated from both sources, expressing identical resistance mechanisms. In U.S. seafood, five out of 47 antibiotics screened for were detected at levels of 0.3 to 7.7 ng/g fresh weight. Although compliant with FDA regulations, the risk for resistance still exists, as even low antibiotic concentrations have been shown to exert selective pressure on bacteria.
Similarly low concentrations of antibiotics were found in U.S. biosolids at levels of 0.6 to 19.1 ng/g dry weight. Of the five antibiotics detected, two have never been reported before in biosolids. Three have never been reported before in U.S. biosolids. Using the raw numbers obtained from antibiotic screenings in biosolids, I assessed the impact of employing four different LC-MS/MS methods, concluding that analysts should experimentally determine the most appropriate quantitation method based on the analyte targeted, matrix investigated, and research goals pursued. Preferred quantitation approaches included the isotope dilution method with use of an analogous standard and, although time and resource demanding, the method of standard addition.
In conclusion, antibiotics introduced into the environment via agriculture, aquaculture, and wastewater recycling pose a combination of chemical and biological threats. Aside from exerting outright chemical toxicity to non-target organisms, antibiotic residues can promote the development of multi-drug resistance in human pathogens. Public health protection approaches to stem the risks posed by animal husbandry may include reserving drugs for exclusive, human use, decreasing their usage altogether, improving reporting efforts, reevaluating existing regulations on agricultural and aquacultural antibiotic usage, and improved risk assessment for biosolids application on land.
ContributorsDone, Hansa Yi-Yun (Author) / Halden, Rolf U. (Thesis advisor) / Haydel, Shelley E (Committee member) / Abbaszadegan, Morteza (Committee member) / Arizona State University (Publisher)
Created2015