Contamination of methylmercury (MeHg) in aquatic products has been a wide spread health concern. The objective of this study is to determine total mercury (THg) and MeHg concentrations in different species of aquatic products from major offshore farms in China, and to assess health impacts from consumption. Results showed that the concentrations of THg and MeHg ranged 5.6–328.4 ng/g (wet weight) and 4.3–303.6 ng/g (wet weight) in aquatic products, respectively, and were very variable among species and origin sources. Target hazard quotient (THQ) suggested that MeHg exposure via consumption posed high health risks to children aged 2–7 and higher income families. Residents above the age of 13 and with low income have relatively lower health risk of MeHg exposure. Health impacts on heart attacks and newborns’ IQ from MeHg exposure were evaluated using dose-response relationships. Results showed that mother’s consumption of aquatic products (at 6 ounce per day) may cause a loss of 0.38 IQ points for newborns. For non-pregnant, consumption of aquatic products may cause an increase rate of mortality and morbidity of heart attacks at 10.59 and 78.45 per 100,000 persons, respectively. The negative health impact of consuming seawater fish was higher than freshwater fish.

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Thesis ( MPH.) --University of Limpopo, 2014 / The purpose of this study was to investigate the knowledge and practices among households at Ga-Mokgwathi Village regarding the disposal of mercury coated bulbs. Cross-sectional design with quantitative approach was used in this study. The study objectives were to determine the knowledge about the disposal methods of mercury coated bulbs and also to determine the practices of handling broken mercury coated bulbs among the villagers of Ga-Mokgwathi. Data collection was done using self-administered questionnaires. Cluster random sampling was used in the study where a total number of 338 households were randomly selected to participate in the study. The results indicated that 36.7 % of the households at Ga-Mokgwathi Village had knowledge of safe disposal methods of mercury coated bulbs, 7.7% were not sure and 55.6% did not have such knowledge. Furthermore, the results indicated that 51.5% of the households had improper practices regarding the handling of broken mercury coated bulbs, 6.2% were not sure and 42.3% had proper practices regarding the handling of broken mercury coated bulb. The results of the study concluded that the majority of people were lacking knowledge of proper disposal methods and the handling of mercury coated bulbs. These results necessitate education of people about the disposal methods and handling of mercury coated bulbs.

This dissertation assesses the factors that lead to the emergence of infectious diseases in children, particularly the emergence of multidrug-resistant organisms (MDROs) and diarrheal pathogens in vulnerable pediatric populations. It includes three manuscripts. The initial study is a systematic review that summarized the role of antibiotic exposure on the acquisition of MDROs in children. Twenty-nine studies met the inclusion criteria and a positive association between prior antibiotic use and subsequent colonization or infection with an MDRO was identified in most studies. There were wide variations among study sites, populations, and definitions of antibiotic use and MDROs. Therefore, limited inferences could be made on which components of antibiotic exposure have the greatest impact on MDRO development. The second analysis examines the relationship between prior stay at a pediatric long-term care (LTC) facility and infection with an MDRO among hospitalized children. This study included 2,945 infections in 258,664 pediatric admissions from 2006 through 2016. At least 1 MDRO was identified in 10% of infections. Of the 1,198 children who had previously resided in a pediatric LTC facility, only 1 child (0.08%) had an MDRO infection. However, prior receipt of pediatric LTC was associated with an increased likelihood of infection (OR 2.4, CI95 1.66 – 3.43), C. difficile infection (OR 2.57, CI95 1.26 – 5.25), days of antibiotic use (OR 1.01, CI95 1.01 – 1.02), length of stay (OR 1.01, CI95 1.01 – 1.01), and death (OR 4.38, CI95 2.93 – 6.55). The concluding study evaluates the association between animals living in or near the home and diarrheal disease in children. This research is a secondary analysis of the Global Enteric Multicenter Study case control study, which investigated the epidemiology of diarrheal illness in children <5 in sub-Saharan Africa and south Asia. Of 9,439 cases and 13,128 controls, 87% had ≥1 animal in their home. In a multivariable analysis adjusting for exclusive breastfeeding, water source, sanitation facility, number of children <5 years in the household, and wealth index, any animal on a child’s compound decreased the odds of diarrhea by 33% (aOR 0.66, CI95 0.59 – 0.74). However, children with diarrhea who had an animal present were not more likely to have a positive stool culture. Overall, the three studies provide a thorough analysis of several factors associated with the infectious disease emergence in children, particularly as related to MDROs and diarrheal disease. Environmental characteristics, including antibiotic use and interaction with animals, were shown to be important factors for emergent infectious disease across diverse settings. The development of pediatric infection prevention interventions should take into consideration environmental risk factors in order to effectively mitigate the risks posed infectious disease emergence.

Decision making in environmental management is faced with uncertainties associated with related environmental variables and processes. Decision makers are inclined to use resources to acquire better information in one or more uncertain variable(s). Typically, with limited resources available, characterizing the feasibility of such investment is desirable yet complicated. In the context of reducing inherent uncertainty, decision makers need to tackle two difficult questions, first, the optimal selection of variable(s) and second, the optimal level of information collection which produces maximum gain in benefits. We develop a new framework to assess the socioeconomic value of potential decisions of collecting additional information for given variable(s) to reduce inherent uncertainty. The suggested framework employs advanced social welfare concepts to facilitate eliciting the social acceptability of decisions to collect better information. The framework produces estimates of changes in utility levels and willingness to pay for target population using the benefit transfer method. The practicality of the framework is established using the following common problems in the field of water resources: 1) the uncertainty in exposure to health risk due to drinking a groundwater source contaminated with a carcinogen, 2) the uncertainty in non point source pollution loadings due to unknown hydrologic processes variability, and 3) the equity level in allocating mitigation responsibilities among polluters. For the three applications, the social acceptability of potential decisions is expressed in monetary terms which represent an extension on typical cost benefit analysis by including the socioeconomic value of a decision. The specific contribution of this research is a theoretical framework for a detailed preliminary analysis to transform and represent the given problem in useable terms for the social welfare analysis. The practical framework is attractive because it avoids the need to employ prohibitively expensive survey-based contingent valuation methods. Instead, the framework utilizes benefit transfer method, which imposes a theoretical behavioral structure on population characteristics such as age and income and to produce empirical estimates for a new problem setting.

The primary purpose of this study was to examine the potential joint influence of need for cognition (NC), the dispositional preference for engaging in (or avoiding) effortful cognitive processing of information, and type of smoking risk message (i.e., factual and evaluative messages similar in message content and length) on the construction of smoking-relevant risk perceptions among college smokers. A secondary purpose was to examine potential mechanisms through which changes in risk perception might occur. 227 college smokers evaluated one of three pamphlets, (1) a factual (i.e., primarily fact-based) smoking risk pamphlet, (2) an evaluative (i.e., primarily emotion based) smoking risk pamphlet, or (3) a control pamphlet unrelated to smoking. Among occasional smokers, NC interacted with type of risk message to influence perceptions of post-pamphlet risk for several of the risk perception outcomes examined. Specifically, smokers lower in NC reported higher levels of perceived risk in response to the evaluative pamphlet whereas smokers higher in NC reported greater perceived risk in response to the factual pamphlet. The interaction did not predict risk perception outcomes among daily smokers. Significant changes in the mechanisms examined were not observed. Findings provide evidence that NC interacts with type of smoking risk message to influence changes in smoking-related health risk perceptions among occasional college smokers. Theoretical and practical implications are discussed.

This thesis deals with the communication of cancer risk in genetic counselling sessions. There are two primary foci that form threads throughout both the theoretical and empirical chapters of the dissertation. The first concerns the meaning of risk as it manifests in familial cancer. In particular, there is a lack of a sound theoretical grounding for the probabilistic aspect of risk that is evident in many forms of risk communication. The thesis aims to illustrate the problem constituted by this lack of theoretical clarity. As most decisions faced by clients arise from attending genetic counselling, it is concluded that clients ' agency is highly constrained when genetic counselling is understood as a process of assisting decision - making. However, genetic counselling can be seen to enable agency when it is conceptualised as a process aimed at making available new medical technologies for the purpose of addressing clients ' own concerns. / Thesis (Ph.D.)--Faculty of Health Sciences, Dept. of Psychology, 2005.

In 1990, the Clean Air Act (CAA) Amendments authorized the regulation of 188 hazardous air pollutants (HAP). Exposure to HAPs at sufficient concentrations and durations can increase both cancer and serious adverse non-carcinogenic effects. The purpose of this study was to conduct a human health risk assessment using data of 43 HAPs from five monitor sites in Portland, Oregon during July 1999-August 2000. HAP concentrations were compared to carcinogenic and non-carcinogenic (health) benchmark concentrations; and emission sources were determined for HAPs that exceeded health benchmark concentrations. Additionally, cancer risks were determined for subpopulations and compared to cancer risks generated for the general population. Results of this study indicate that 20 HAPs exceeded carcinogenic benchmark concentrations (corresponding to a risk level of 1 x 10������) in at least one location. Chromium compounds posed the highest cancer risk (3.5 x 10������). Seventeen HAPs exceeded carcinogenic benchmark concentrations at all five sites. Seventy-five percent (%) of the total cumulative cancer risk was contributed by chromium compounds, 1,3-butadiene, formaldehyde and 1,1,2,2-tetrachloroethane. Three HAPs, chromium compounds, acrolein, and formaldehyde, exceeded non-carcinogenic hazard ratios of 1.0. Releases from area sources accounted for the largest percentage of HAPs that exceeded health benchmark concentrations. With respect to subpopulations, asthmatics teenagers (age 11-16) and asthmatic adults (age 18-50), had slightly elevated cancer risks of 1.4 x 10������ and 1.2 x 10������. respectively, compared to the general population risk level of 1 x 10������. Results of this study indicate that several HAPs pose a potential human health concern in Portland and that efforts should be made to reduce their emissions. Additional studies are warranted to further assess potential human health risks and the extent of HAPs in Portland, Oregon. / Graduation date: 2003

The goal of the project was to develop a functional prototype of an environmental risk assessment parameter database on the World-Wide Web. The ability to develop a consolidated environmental database has become possible due to the phenomenal growth of the Internet and the World-Wide Web over the past few years. A large number of environmental resources do currently exist; however, with the large volume of information available, access, management, reliability, and retrievability have become increasingly difficult. To illustrate the prototype database, a practical environmental concern and the tools necessary to evaluate and characterize that concern were needed. Uranium (�������U) daughters leaching from abandoned mill tailing piles at three abandoned uranium mines in southwestern Colorado were chosen to demonstrate the database concept. The RESRAD environmental pathway modeling code served as the evaluation and characterization tool. Due to the size and complexity of RESRAD, a single radionuclide release rate equation was isolated as a controllable component of the code. The equation was a small part of the water pathway factor and examined the rate at which radionuclides absorbed in soil were leached by infiltrating water. This serves as the source term for groundwater contamination and directly applies to the �������U progeny leaching from mill tailing piles scenario. Parameters selected from the equation dealt with the background data that directly influenced the mobility of contaminates in the environment. Environmental data for the three Colorado sites were gathered and interpreted. Probability Density Functions (PDFs) were developed for input parameters and the results were then incorporated into the web site. / Graduation date: 1998

Quantitative soil ingestion studies employing a mass balance tracer approach have been used to determine soil ingestion rate for use in human health risk assessments (HHRAs). Past studies have focused on soil ingestion in populations living in urban/suburban environments and the results have been highly variable. Moreover, there is a paucity of reliable quantitative soil ingestion data to support human health risk assessments of other lifestyles that may be predisposed to ingesting soil, such as indigenous populations following traditional lifestyles. Thus, the primary objective of the research was to determine if populations following lifestyles typical of traditional land use practices in rural or wilderness areas ingest more soil than populations living in urban or suburban environments. Further, the research investigated the use of alternative mass balance tracers, specifically isotopes of the 238U and 232Th decay series, to reduce soil ingestion estimate variability. Mass balance tracer methods were developed and validated in a pilot canine study, and methods using isotope tracers were adapted to permit quantification of sediment ingestion in the benthic fish Moxostoma macrolepidotum (Shorthead Redhorse Sucker). A pilot human soil ingestion study of 7 subjects from an Aboriginal community in British Columbia was conducted over a 3-week period. The mean soil ingestion rate calculated using the daily means of the 4 elemental tracers with the lowest food-to-soil ratios (i.e., Al, Ce, La, Si) was observed to be approximately 74 mg d-1 (standard deviation 91 mg d-1), The median soil ingestion rate was 60 mg d-1, and the 90th percentile was 196 mg d-1. These soil ingestion rate estimates are higher than those currently recommended for HHRAs of adults, and higher than those obtained in most previous studies of adults. However, the estimates are much lower than the earlier qualitative assessments for subsistence lifestyles (i.e., 330-400 mg d-1). The study results also demonstrated that isotopes of the 238U and 232Th decay series radionuclide are not reliable mass balance tracers for estimating soil ingestion in humans; however, they may be useful for quantifying soil and sediment ingestion in wildlife.