Browsing by Author "Hinton, David E"
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Item Open Access A Critical Review on Childhood Hyperactivity and Artificial Food Colors(2012-04-26) Li, FeifeiArtificial food colors (AFCs) are dyes, pigments, or other substances that can impart color to either of a variety of foods making them attractive, appealing, appetizing, and informative. However, the AFCs have long been suspected of triggering attention deficit hyperactivity disorder (ADHD) in children. The U.S. Food and Drug Administration (FDA) and European Food Safety Authorization (EFSA) are responsible for assuring that citizens use the AFCs safely and appropriately. Since 1963, nine certified color additives have been approved for use in the United States, and 3 of the 9 were already banned in Europe. By comparing the AFCs legislation status in U.S. and E.U., and analyzing clinical data from academia, government and advocacy groups (NGOs), my review questions the use of AFCs in U.S. foods, and recommends that more epidemiology studies followed by carefully designed animal experiments should be done to determine whether these compounds are appropriate in food manufacturing. I recommend that the legislature move rapidly to enhance the reliability and safety of our food system.Item Open Access Acute Toxicity and Sub-Lethal Effects of Non-Point Source Pollutants on Invertebrates(2007-05-07T19:07:30Z) Romano, Jocelyn AnnNon-point source pollution is not generated from any single source, rather can arise from a mixture of agricultural, residential, and industrial activities. As a result of these activities millions of tons of chemicals enter into aquatic environments annually with the potential to disrupt the fragile ecosystems existing within. Common anthropogenic compounds most frequently seen in estuarine environments include pesticides, antifoulants, polycyclic aromatic hydrocarbons (PAH), and industrial solvents. This dissertation examines the acute toxicity and sub-lethal effects of diuron, CuPT, B(a)P, and styrene in the mud snail, Ilyanassa obsoleta, the American oyster, Crassostrea virginica, the sea urchin, Lytechinus variegatus, and/or the barnacle, Amphibalanus (= Balanus) amphitrite. In addition, the general effects of non-point source pollution within the Rachel Carson Estuarine Research Reserve (RCERR) were examined at six sites in order to gain a better understanding of the current health of this unique habitat. Of the four compounds tested, only the industrial solvent, styrene, resulted in an LC50 (1341 µg L-1, I. obsoleta) that was within the range of currently reported environmental levels. Diuron and CuPT did not elicit mortality at environmentally relevant concentrations, but did significantly reduce fecundity in I. obsoleta and C. virginica and fertilization success and larval development in L. variegatus. The only notable sub-lethal effect elicited by the PAH, benzo(a)pyrene, was a significant decrease in egg capsule production by I. obsoleta following exposure to concentrations as low as 50 µg L-1. Within the RCERR, animals from Sites 4, 5, and 6 were observed to have significant differences with respect to fecundity, condition index, and/or ECOD activity when compared to conspecific organisms from control Site 1. This is most likely a consequence of their proximity to anthropogenic sources. Large variation in mortality (15-98.9%) was observed when families of A. amphitrite from a single population where exposed to CuPT. It is often difficult to extrapolate data from laboratory findings into natural populations. Frequently the organisms used under laboratory conditions are genetically very similar, while field population can vary with anthropogenic exposure. Caution must be taken when developing protocols for risk assessment to ensure that actual environmental conditions are being represented.Item Open Access ADDRESSING THE WATER CRISIS IN OMAN – NEGOTIATING WITH WATER USERS THROUGH IMPLEMENTATION OF WATER DEMAND MANAGEMENT(2011-04-29) Manneh, MichaelCountries worldwide are facing freshwater challenges in both quantity and quality in meeting increased water demand. Historically, increasing water supply solved deficit problems. Today, the situation is different because most of the readily accessible resources have already been used and the majority of these sources are under pressure. In the case of the Sultanate of Oman, the accessible water resources have been fully exploited and development of the more remote sources would require large capital investment. Non-traditional sources, such as desalination, wastewater reuse, etc., are currently expensive and of limited capacity. Therefore, water users have become over-reliant on excessive abstraction of groundwater to meet growing demand. Since the 1970s, this has led to a year-on-year water deficit, progressive lowering of the water table and salt-water intrusion into coastal aquifers with adverse and, in some cases, irreversible damage to the groundwater resource and the environment. Oman’s current supply-driven approaches for the management of water resources are no longer sustainable. To prevent the current water deficit in fresh water resources from worsening, it is necessary to explore a new approach to water management. This master’s project explores the various options available in the sultanate of Oman under Water Demand Management (WDM). Through questionnaires and interviews administered to stakeholders including: water professionals, municipal and irrigation water users, and expatriate farmers, this paper concludes that awareness of the water crisis exists amongst all stakeholders (municipal and agricultural users). Yet a comprehensive master plan to phase various recommendations must begin with the support of the agricultural sector, currently the largest consumer of fresh water in Oman. The process must be adaptive with concerns raised by all players being considered and changes instituted in a phased process. The results of the research conclude that Water Demand Management is acceptable as a conservation tool, but requires an equitable method holding all users accountable for it to be effective.Item Open Access An Analysis of Water Management Strategies in Drought Prone Areas(2018-04-26) Vogel, SarahThere is an old adage in the West: “whiskey is for drinking; water is for fighting”. In the American West, as well as locales all over the globe, water scarcity is a subject rife with conflicts and emotion. Human beings approach drought in reactionary ways. Rather than plan for the eventuality of drought, societies enact drought policy or regulations well into, and not before experiencing drought conditions. Researchers have predicted that more than half of humanity will live in water-stressed areas in the near future. Understanding the significant role drought plays in water management and the costs of reactionary decision making can help stakeholders create proactive approaches to water allocation. This paper seeks to understand how drought affects water management strategies; how regulation is affected by drought conditions; how local agencies and state authorities interact to manage water resources in California; and how California water management compares to water management strategies employed in other drought prone areas of the globe.Item Open Access AN OVERLAY DISTRICT TO ADDRESS STORMWATER RUNOFF QUANTITY AND QUALITY IN THE DISTRICT OF COLUMBIA: EMPHASIS ON THE ANACOSTIA RIVER(2011-04-28) Backhus, TheresaThis Masters Project (MP) addresses the serious water quality issue of the Anacostia River in the District of Columbia. Focusing on non-point source pollution, the research explores the need for a more unified approach to stormwater runoff policy in DC and how specific examples from across the country can be applied to create a solution. It provides recommendations that will help reduce the burden on the combined sewer overflow (CSO) system that empties into the Anacostia River. Reducing the burden on the CSO system will reduce the number of overflow events during storms. Reducing overflow events and increasing runoff infiltration will have a direct effect on the water quality of the Anacostia River by reducing the quantity of raw sewage, trash, toxicants, and debris that enter the river. The research questions explored are: •What are the roadblocks to effective stormwater management in the District of Columbia? •What are the most effective strategies to eliminate CSO events? •How can a DC stormwater overlay district improve the water quality of the Anacostia River? Extensive literature review and interviews were conducted to define the current stormwater management approach in the District of Columbia. The interviews clarified common goals and conflicting objectives for stormwater management, as well as the degree of stormwater management fragmentation in the District. Analysis of the research and interviews led to the identification of gaps in stormwater policy. Further research was conducted to seek successful, model, local government stormwater district policies from across the country. Additional interviews were conducted with representatives of these municipalities (South Burlington, VT, Philadelphia, PA, Pittsburgh, PA, Anne Arundel County, MD, and Portland, OR) to learn about the development and implementation of the specific program, as well as its successes and opportunities for improvement. A cross-case comparison was conducted to compare each program’s features and explore its applicability to the District of Columbia. Limited content recommendations were then developed for an Anacostia-specific Stormwater Management Overlay District, and implementation strategies were suggested. The results of the research, interviews, and analysis indicate that a Stormwater Management Overlay District would be an effective tool to reduce the burden on the Anacostia River CSO system. The overlay district will help to increase stormwater infiltration as runoff passes through the watershed. This tool could be used as a model for urban cities across the country that are facing similar CSO and stormwater management issues.Item Open Access Assessing the Potential of Creating a Stream Mitigation Bank on the Tar River(2015-04-24) Yang, Cha; Yang, NuoerDevelopment projects discharging fill material into any U.S. navigable waters require approval under Section 404 of the Clean Water Act, and must show that steps were taken to avoid environmental impacts. Unavoidable impacts require compensatory action to mitigate environmental loss. Mitigation banking serves as an outlet to provide compensatory mitigation to offset those environmental impacts on streams and wetlands. The Tar River Land Conservancy, a land trust in North Carolina focused on preserving the natural ecosystem on the Tar River basin, is interested in the prospectus of creating a mitigation bank. Three main objectives of the project include 1) identifying and ranking sites suitable for a mitigation bank, 2) conducting a literature review to determine liabilities/pitfalls of mitigation banking and develop recommendations to overcome the challenges, and 3) identifying elemental factors to creating a sustainable business plan that also contributes to the mission of the land trust. The findings aim to assist the decision-making process for the client to ascertain the potential of pursing the business endeavor.Item Open Access Assessing the well water quality in a rural Georgia county: Do Washington County citizens need to worry?(2008-08-27T02:58:24Z) Hitchcock, KristenUnder the Safe Drinking Water Act, public water sources must be monitored for contaminants; and the results are made public. However, this Act does not cover private wells, leaving a significant portion of the population unprotected. In one rural Georgia county, Washington, an estimated 3,997 wells are currently in use. Local health officials believe that well contamination is a problem for the people using these wells. The purpose of this project was to take the available data and briefly assess the state-of-affairs for the county. After researching topics unique to Washington County and determining potential sources of well water contamination, aluminum, silica, manganese, total and fecal coliform bacteria, pH, and hardness were chosen for assessment. Despite limitations in the data, this study filled an important knowledge gap for Washington County in that no analysis had been conducted of the available data. For the parameters tested, it was concluded that Washington County well owners were not facing a significant health threat. Additionally, differences in contaminant levels among soil type and year of sample were not significant. The most important problem currently facing the county is lack of data. Washington County must begin to test wells more frequently to better assess contaminants of concern and to focus education and remediation efforts.Item Open Access A Risk‐Risk Trade‐off: Insecticide Use for Malaria Control(2011-04-29) Pfau, KristenMalaria is among the top causes of death in low-income countries. Because it is transmitted through a mosquito vector, programs to reduce or control these insects receive much attention. Recently, concerns have increased regarding possible chronic reproductive impairment following exposure to insecticides used in mosquito control. This project examines the human health benefits and potential human health consequences of indoor residual spraying (IRS), an increasingly popular method of insecticide use for malaria control. Meta-analysis was used to aggregate the results of published trials on efficacy of IRS in reducing malaria prevalence in a region. Statistical analysis incorporating results of all these studies led to general conclusions about the impact of any IRS program, and provided insight as to what variables resulted in greater effects in one community over another—for example, the type of insecticide used, the initial malaria prevalence in the community, and the time frame of the program. Next, the potential chronic human health consequences were assessed through a review of chemical, toxicological and epidemiological studies. Research focused on two chemicals, lambda-cyhalothrin and DDT. Screening of chemical properties and toxicological studies indicate a potential risk for negative human health outcomes from exposure to both chemicals. Identification and critique of several epidemiological studies that link exposure to IRS with negative reproductive health outcomes verify this risk for DDT. Finally, a series of interviews with malaria control experts in Tanzania provided insight on the cumulative perceptions of decision-makers regarding both the benefits and the consequences illustrated in the previous sections, as well as a variety of other facets of malaria prevention. While this project only presents a small portion of benefits and risks associated with using insecticides for malaria control, it is evident that the current risk assessment-risk management paradigm is not adequate for informing decisions on risk tradeoffs. The benefits and risks need to be considered holistically, not independently, in order to inform quality risk policies. Based on the case study of insecticide use for malaria control, a new framework is suggested in which risk tradeoffs are approached in an interdisciplinary, collaborative manner.Item Open Access CAFOs as Hotspots: Effect on Ecosystem Services and Needed Change in Environmental Leadership(2012-04-27) Olivier, SharMany Americans are neither aware that 99 percent of their meat consumed in the United States is produced by large-scale factory farms; nor, are they aware of the deleterious effect these operations have on environmental systems. In North Carolina, the country’s second pork producing state, the lack of public awareness and public misperception have a direct impact on environmental decision making, which further exacerbates the challenges posed by concentrated animal feeding operations (CAFOs). As with all businesses they operate based on the law of supply and demand, the growing number of CAFOs is directly related to increased meat consumption and corporate desire for higher profits since the 1950s. This project seeks to determine whether understanding CAFOs as hotspots and increasing public awareness about industrial meat production can effectively influence positive environmental change, from the personal food choices of individuals, to the political decisions of leaders and policy makers.Item Open Access Characterization of Fxr Alpha in Medaka and Its Involvement in Hepatobiliary Injury(2009) Howarth, Deanna LynneThe liver is a primary target for toxicants and/or their metabolites. Selected fish species now serve as model organisms for laboratory investigations of toxic responses in the liver. One such model is the Japanese medaka (Oryzias latipes), a small freshwater teleost with a robust history of usage in liver and biliary toxicity studies. The structural components of the medaka hepatobiliary system have been well-described by recent studies in two- and three-dimensional contexts, but efforts to characterize the molecular mechanisms underlying critical medaka liver functions during normalcy remain sparse. This dearth of information makes it difficult to definitively characterize toxic responses in this model organism. A crucial transcription factor underlying proper hepatobiliary function in both mammalian and non-mammalian species is the farnesoid X receptor alpha (FXRα), a member of the nuclear receptor superfamily that plays a key role in bile acid homeostasis. This dissertation describes the function of medaka fxrα during both normalcy and toxicity.
To achieve this overall objective, in vitro techniques were first employed to study the function of medaka fxrα. Two isoforms of fxrα that differ in the AF1 domain, Fxrα1 and Fxrα2, were isolated from liver cDNA and are the result of alternative splicing of one gene locus. Fxrα2 responded significantly to C24 bile acids and the synthetic FXRα agonist GW4064. On the other hand, Fxrα1, despite having an identical ligand-binding domain to that of Fxrα2, showed no response to any agonists tested by transient transactivation assays. Furthermore, Fxrα2 interacted with nuclear receptor coactivators PGC-1α and SRC-1 in mammalian two-hybrid assays while Fxrα1 did not. These findings point to a significant importance of the AF1 domain to overall receptor structure and function.
Following in vitro functional characterization, in vivo experiments using medaka larvae were performed to determine fxrα's function during normalcy. Quantitative, real-time PCR data demonstrated that Fxrα1 is highly expressed in adult liver, while Fxrα2 is expressed predominantly in gut. Fxrα1's expression was higher than Fxrα2 in embryos and larvae at all developmental timepoints tested. In vivo exposures of medaka hatchlings to GW4064 at various doses significantly altered expression of defined FXRα targets, including: bile salt export protein (BSEP), small heterodimer partner (SHP), and cytochrome P450 7A1 (CYP7A1). Surprisingly, numerous sublethal hepatic alterations to hepatocytes and bile preductular epithelial cells (BPDECs) were observed following exposure to GW4064; alterations included: lipid accumulation, glycogen depletion, mitochondrial swelling and rupture of mitochondrial membranes, disruption of endoplasmic reticulum, and apoptosis. Significant lipid accumulation, as revealed by oil red O whole mount staining of larvae, was also noted at lower doses of GW4064. These findings were the first observations of sublethal hepatotoxicity of GW4064; to date, no studies in the mammalian literature reported alterations following its administration.
Because of studies in the mammalian literature that demonstrated alleviation of cholestatic injury induced via the classic hepatotoxicant α-naphthylisothiocyanate (ANIT) by GW4064, it was originally hypothesized that a similar finding would be observed in medaka coexposed to these compounds. However, because of GW4064's ability to induce sublethal hepatic alterations in medaka, it was anticipated that its coadministration with ANIT would result in enhanced toxicity rather than alleviation as described in rodent models. However, despite the sublethal alterations induced by 1 uM GW4064, alleviation of toxicity following exposure to 15 uM ANIT was observed. Surprisingly, reduction of GW4064's toxicity was also observed in larvae exposed to both compounds. These investigations of fxrα function are an important and essential component in furthering our understanding of hepatobiliary toxicity in small aquarium fish models of human liver disease. These collective findings have created molecular underpinnings necessary for understanding medaka hepatobiliary function during normalcy and toxicity.
Item Open Access Chronic microfiber exposure in adult Japanese medaka (Oryzias latipes).(PloS one, 2020-01) Hu, Lingling; Chernick, Melissa; Lewis, Anna M; Ferguson, P Lee; Hinton, David EMicroplastic fibers (MFs) pollute aquatic habitats globally via sewage release, stormwater runoff, or atmospheric deposition. Of the synthetic MFs, polyester (PES) and polypropylene (PP) are the most common. Field studies show that fish ingest large quantities of MFs. However, few laboratory studies have addressed host responses, particularly at the organ and tissue levels. Adult Japanese medaka (Oryzias latipes), a laboratory model fish, were exposed to aqueous concentrations of PES or PP MFs (10,000 MFs/L) for 21 days. Medaka egested 1,367 ± 819 PES MFs (0.1 ± 0.04 mg) and 157 ± 105 PP MFs (1.4 ± 0.06 mg) per 24 hrs, with PP egestion increasing over time. Exposure did not result in changes in body condition, gonadosomatic- or hepatosomatic indices. PES exposure resulted in no reproductive changes, but females exposed to PP MFs produced more eggs over time. MF exposure did not affect embryonic mortality, development, or hatching. Scanning electron microscopy (SEM) of gills revealed denuding of epithelium on arches, fusion of primary lamellae, and increased mucus. Histologic sections revealed aneurysms in secondary lamellae, epithelial lifting, and swellings of inner opercular membrane that altered morphology of rostral most gill lamellae. SEM and histochemical analyses showed increased mucous cells and secretions on epithelium of foregut; however, overt abrasions with sloughing of cells were absent. For these reasons, increased focus at the tissue and cell levels proved necessary to appreciate toxicity associated with MFs.Item Open Access Community-Based Environmental Management: A Tool For Natural Disaster Risk Reduction In Haiti?(2006) Eichler, LisaThis report provides an in-depth analysis of how Haiti can successfully apply community-based environmental management as a tool for reducing its risks to natural disasters. The approach to answer this policy challenge is three-pronged. First, this report analyzes Haiti’s disaster risk profile and establishes the various linkages between environmental degradation and natural disasters. Second, the report utilizes community-based environmental management literature and worldwide ‘Best Practice Examples’ of local disaster risk reduction initiatives to create a framework for risk-reducing community-based environmental management. Third, the report evaluates the soundness of this new framework by applying it to one Haitian community – Fondwa. On a more global scale, this study contributes valuable information on how communities can adapt and implement community-based environmental management practices in order to reduce their vulnerabilities to disaster impacts while simultaneously tackling environmental degradation.Item Open Access Embryotoxicty in medaka (Oryzias latipes) following exposure to select alkaline earth metals: a screening bioassay(2008-04-25T15:34:27Z) Nelson, ClayEnvironmental exposure to radium, a radioactive alkaline earth metal, and barium, a chemically similar but non-radioactive earth metal, are of growing concern. Radium and barium levels in some groundwater aquifers exceed maximum contaminant levels, and future groundwater resources may be increasingly at risk. Surface waters may also be at risk from disposal of residual waters enriched in metals, including radium and barium, from the increased use of chemical filtration processes such as ion exchange or reverse-osmosis desalination to treat groundwater. Leaching of uranium mine tailings generated during mining activities and industrial uses of barium, including use in high-density oil and gas well drilling muds, serve as additional anthropogenic sources of these metals to surface waters. Currently, there is a lack of information on the effects of radium and barium on fish development. Such lack of data may complicate ecological risk assessment, as recruitment of young of the year fishes have been demonstrated to be major drivers of fish populations. I employed a high throughput, screening level bioassay to experimentally characterize toxicity in developing medaka fish embryos and eleutheroembryos (an embryonic phase starting with hatching and ending with absorption of yolk sac) following exposure to radium (radium-226 chloride) and barium (barium chloride). The ability to follow individual embryos over time and view embryonic development through the transparent chorion were key design characteristics of this experiment. Two endpoints, time to hatch and mortality, were concurrently assessed. Results of the bioassay failed to demonstrate evidence of embryotoxicity from exposure to radium at levels up to 60,000 pCi/L. Exposure to high levels of barium (100 ppm) resulted in earlier hatching time. Additionally, an increase in post-hatch mortality was observed, suggesting that the chorion may play a protective role with regard to alkaline earth metal exposure. Water chemistry appeared to affect the magnitude of post-hatch mortality, although results between different exposure scenarios used in the study were ambiguous. The lack of observed embryotoxicity from radium exposure does not definitively demonstrate that radium is not toxic, as other endpoints not assessed in this screening level bioassay may be more sensitive indicators of toxicity and effects from exposure during development may manifest themselves at later life stages. Results of the barium analysis suggest that young of the year fishes may be particularly sensitive to acute exposure to high levels of alkaline earth metals. This suggests that better management of radium and barium in the environment, including the disposal of brine solutions enriched in alkaline earth metals to surface waters, may be needed to reduce ecological risks to fish populations.Item Open Access Evaluating Variation in Terrestrial Plant Toxicity Tests(2008-04-25T14:28:35Z) Kurnath, LindseyThe Office of Pesticide Programs of the U.S. EPA conducts the national pesticide review process, under authority granted by FIFRA. Ecological risk assessments are performed on many different organisms to identify ecosystem-level impacts. Among these organisms are non-target terrestrial plants, which are specifically used to understand the risk to plants exposed to spray drift or runoff. Guidelines were developed from field-based methods rather than a traditional interlaboratory precision analysis, thus the natural variation in measurement endpoints for terrestrial plant toxicity tests has not been established. Recognizing the inherent sensitivity of the assessments currently conducted helps the U.S. EPA better understand the implications of the pesticide review process. The following report aims to determine the natural variability of the response endpoints (i.e. emergence, plant length, plant weight) for these studies. This project involved the development and design of two databases in MS Access, the selection of control data from existing studies, an analysis of the among and within laboratory variability in response measures, and a trend analysis for environmental conditions. The findings supported the currently accepted coefficient of variation (CV) of 20% used by the U.S. EPA. All seedling emergence studies in all laboratories had average CV values of less than 40% and laboratories who were responsible for conducting a majority of the studies exhibited CV values less than 20%. Similar patterns were observed in the length data from the vegetative vigor studies. The weight data presented variation that was often greater than the expected 20% even for the most frequently tested species. The most data was available for corn and soybean plants and these species were also the least variable. The historical value of a 20% coefficient of valuation seems to be, on average, an acceptable value for the terrestrial plant toxicity tests used for pesticide registration. The data of this report indicates particular species, specifically corn and soybean, tend to have CV values closer to 10%. The addition of more data and a more sophisticated analysis into the underlying causes of variation could reveal a lower CV across all species.Item Open Access EVALUATION OF RECLAIMED WATER FOR COOLING IN COAL-FIRED POWER PLANTS OF NORTH CAROLINA(2012-04-27) Lee, Meng-YingCooling systems for thermoelectric power generation are responsible for 39% of the freshwater withdrawal in the US. As the demand for electricity increases, finding alternative water source is crucial. Studies have shown that reclaimed water can be used in certain applications, including makeup water in power plant cooling systems. Concerns about reclaimed water for cooling purpose include potential environmental health impacts during the cooling process, and reclaimed water availability for the cooling systems. This study reviewed the federal and NC state regulations governing the use of reclaimed water for cooling purposes, and the toxicological and epidemiological studies on potential human health impacts of hazards emitted from the cooling systems. In addition, a scenario analysis was conducted to assess reclaimed water availability for coal-fired power plants in NC regarding water transportation costs. The result showed that using a spatial-economic optimization model considering pipeline construction conditions and the potential of pipeline merging can effectively minimize the pipeline construction cost and obtain the least-cost pipeline network infrastructure. The unit transport cost analysis for each power plant also provided the power plant companies the practical information they need for evaluating the feasibility of reclaimed water application for each power plant. Considering the potential issues from water quality and availability, establishing stable supply-demand relationships between reclaimed water source and power plants can be beneficial for both water quality control and makeup water security for power plants.Item Open Access Evaluation of the Beneficial Re-Use of Produced Water: A Review of Relevant Guidelines and Produced Water Toxicity.(2011-04-29) Adebambo, OluwadamilareAs global demand and production of fossil fuel (oil and gas) continues to increase, so do their associated environmental footprints. One example is produced water (PW), i.e. water used or extracted along with oil. Presently, over 5 billion gallons of PW is generated daily. In the past, produced water was simply re-injected into the empty oil well after extraction. As freshwater supply becomes increasingly scarce, PW can become an important water source after suitable treatment. This masters’ project investigates the current beneficial reuse options of PW and the potential environmental risks that could result from this reuse My literature review was conducted on PW generation during oil and gas extraction, and focused on significant constituents and their characteristics, treatment methods and current regulations guiding reuse. I concentrated on land-based oil and gas extraction since these activities use valuable freshwater. Peer-reviewed publications were used when available but industry and consultant reports were also used when necessary. Researchers at Clemson University with ongoing projects on PW treatment were interviewed for more up to date information. A large body of literature confirms that toxicity of PW varies with age of the oil well and between different operations. However, salinity, dissolved oil and aromatics were often the constituents of concern. Salinity limits also confound PW toxicity assessment as current regulatory test organisms are salt intolerant. Therefore there is great need to develop cost-effective technology for desalination and to include more salt tolerant toxicity test species. Based on these findings, a decision framework was developed to better guide the beneficial reuse of PW in such a way that environmental risks are considered and minimized.Item Open Access Factors Affecting Ultraviolet Exposure in Coastal Waters of the Florida Keys: Effects on Nearshore and Offshore Coral Reef Tracts(2007-05) Rosenfeld, CarlaWe have investigated how the loss of chromophoric dissolved organic matter (CDOM) in the water column due to photobleaching allows for increased penetration of UV radiation near coral reefs in the Florida Keys. Extended exposure to UV may contribute to coral bleaching episodes. CDOM serves as the primary control on UV exposure of corals in this region because it strongly absorbs UV radiation, especially damaging UVB wavelengths. An important fraction of the CDOM pool in Florida Keys coastal waters is transported from Florida Bay, but local CDOM sources including seagrasses, mangroves, and Sargassum colonies may also be substantial. CDOM samples collected along transects near the reefs and from mangrove leaf and Sargassum incubation experiments were exposed to simulated solar radiation for up to 120 hours. Calculated photobleaching rates (k305) of CDOM produced by mangrove leaf litter and Sargassum colonies (approx. 0.02 hr^-1) were an order of magnitude greater than rates measured for the water column samples (0.002 hr^-1). However, our experiments indicate that photobleaching of CDOM in natural waters near the reefs can still be substantial during summer months and may allow UVB levels at 4 m depth (typical depth of fringing reefs) to increase by as much as 20%. Corals located in shallower waters (2 m) along the reef line may experience up to a 40% increase in UVB exposure due to loss of CDOM.Item Open Access Hepatic Responses of Juvenile Fundulus heteroclitus from Pollution-adapted and Nonadapted Populations Exposed to Elizabeth River Sediment Extract.(Toxicol Pathol, 2016-07) Riley, Amanda K; Chernick, Melissa; Brown, Daniel R; Hinton, David E; Di Giulio, Richard TAtlantic killifish (Fundulus heteroclitus) inhabiting the Atlantic Wood Industries region of the Elizabeth River, Virginia, have passed polycyclic aromatic hydrocarbon (PAH) resistance to their offspring as evidenced by early life stage testing of developmental toxicity after exposure to specific PAHs. Our study focused on environmentally relevant PAH mixtures in the form of Elizabeth River sediment extract (ERSE). Juvenile (5 month) F1 progeny of pollution-adapted Atlantic Wood (AW) parents and of reference site (King's Creek [KC]) parents were exposed as embryos to ERSE. Liver alterations, including nonneoplastic lesions and microvesicular vacuolation, were observed in both populations. ERSE-exposed KC fish developed significantly more alterations than unexposed KC fish. Interestingly, unexposed AW killifish developed significantly more alterations than unexposed KC individuals, suggesting that AW juveniles are not fully protected from liver disease; rapid growth of juvenile fish may also be an accelerating factor for tumorigenesis. Because recent reports show hepatic tumor formation in adult AW fish, the differing responses from the 2 populations provided a way to determine whether embryo toxicity protection extends to juveniles. Future investigations will analyze older life stages of killifish to determine differences in responses related to chronic disease.Item Open Access Increased coiling frequency linked to apoptosis in the brain and altered thyroid signaling in zebrafish embryos (Danio rerio) exposed to the PBDE metabolite 6-OH-BDE-47.(Chemosphere, 2018-05) Wang, Feng; Fang, Mingliang; Hinton, David E; Chernick, Melissa; Jia, Shenglan; Zhang, Yingdan; Xie, Lingtian; Dong, Wenjing; Dong, WuPolybrominated diphenyl ethers (PBDEs) are a group of brominated flame retardants that are ubiquitously detected in the environment and associated with adverse health outcomes. 6-OH-BDE-47 is a metabolite of the flame retardant, 2,2',4,4'-Tetrabromodiphenyl ether (BDE-47), and there is increasing concern regarding its developmental neurotoxicity and endocrine disrupting properties. In this study, we report that early life exposure in zebrafish (Danio rerio) embryos to 6-OH-BDE-47 (50 and 100 nM) resulted in higher coiling frequency and significantly increased apoptotic cells in the brain. These effects were partially rescued by overexpression of thyroid hormone receptor β (THRβ) mRNA. Moreover, exposure to 100 nM 6-OH-BDE-47 significantly reduced the number of hypothalamic 5-hydroxytryptamine (5-HT, serotonin)-immunoreactive (5-HT-ir) neurons and the mRNA expression of tryptophan hydroxylase 2 (TPH2). These results indicate that 6-OH-BDE-47 affected thyroid hormone regulation through THRβ and negatively impacted the nervous system, in turn, affecting coiling behavior. Correlations of these endpoints suggest that coiling frequency could be used as an indicator of neurotoxicity in embryos.Item Open Access Integration of Risk and Ecology into Water Quality Criteria for the Protection of Aquatic Life(2012-04-26) Workin, RachelThe demand for increased consideration of ecology has been an important driver of developments in ecotoxicology, a field that originally relied more heavily on the principles of human toxicology. However, translating these developments into policy-level applications has been hindered by a lack of formalized acceptance and guidance. This study analyzes the potential for applying advances in ecotoxicology and risk assessment to the United States Environmental Protection Agency’s process for developing water quality criteria for the protection of aquatic life. The current status of ecology in this process is assessed and suggestions for further integration of ecological principles are provided. By increasing consideration of ecology in the criteria development process, water quality criteria will be more realistic and achieve optimum protection of aquatic ecosystems.