Bibliography: leaves 263-270.

Includes bibliographical references (leaves 232-247). Obtained information on dental caries and fluorosis among a representative sample of Vietnamese children. Also collected information on factors likely to influence caries experience and dental fluorosis and undertook statistical analyses to examine the relationship between fluoride in drinking water, dental caries and dental fluorosis

Bibliography: leaves 106-114.

The aim of this thesis is to demonstrate the importance of walking to public health. The first part is characterized by epidemiological research. First, a typology for the measurement of walking is developed. A systematic review is conducted of observational studies to determine the health benefits of walking in its own right. Studies consistently confirm that 30 minutes walking on most days of the week is sufficient to reduce the risk of cardiovascular diseases and non-communicable disease risk. Then, a series of epidemiological analyses describes the prevalence and correlates of walking, using multiple health and non-health surveillance data sets. Surveillance data indicate that the prevalence of walking at the above recommended levels is low across all domains. Between 1991 and 2001 an increase in walking occurred, and was the main contributor to reductions in leisure time physical inactivity; however, the proportion of the population who achieved the recommended amount of physical activity by walking did not change in leisure and transport domains. The next part of the thesis is characterized by health promotion research examining the impact of three population-based approaches to increasing walking among Australian adults. The first was an evaluation of a conversion of rail to trail, as an environmental change intervention; the second was a mass media campaign promoting walking to work, and the third was a targeted print media walking program. Providing environmental supports with minimal promotion had no effect on walking. A nation-wide mass media campaign promoting walking to work increased walking and other moderate intensity physical activity, but process evaluation indicated other promotional efforts contributed as well. The targeted print media randomised trial had the greatest effect on walking, but the increases were not greater than spontaneous change in the control. Increases in total physical activity were achieved only when the intervention was supplemented by the use of a pedometer. The expectation that broader approaches to the promotion of walking will bring about changes at the population level, were not corroborated by these case studies. There is a need for enhancement of walking-specific interventions to influence total PA at the population levels.

This thesis reports on a quantitative exposure assessment and on an analysis of the attributes of the data used in the estimations, in particular distinguishing between its uncertainty and variability. A retrospective assessment of exposure to benzene was carried out for a case control study of leukaemia in the Australian petroleum industry. The study used the mean of personal task-based measurements (Base Estimates) in a deterministic algorithm and applied factors to model back to places, times etc for which no exposure measurements were available. Mean daily exposures were estimated, on an individual subject basis, by summing the task-based exposures. These mean exposures were multiplied by the years spent on each job to provide exposure estimates in ppm-years. These were summed to provide a Cumulative Estimate for each subject. Validation was completed for the model and key inputs. Exposures were low, most jobs were below TWA of 5 ppm benzene. Exposures in terminals were generally higher than at refineries. Cumulative Estimates ranged from 0.005 to 50.9 ppm-years, with 84 percent less than 10 ppm-years. Exposure probability distributions were developed for tanker drivers using Monte Carlo simulation of the exposure estimation algorithm. The outcome was a lognormal distribution of exposure for each driver. These provide the basis for alternative risk assessment metrics e.g. the frequency of short but intense exposures which provided only a minimal contribution to the long-term average exposure but may increase risk of leukaemia. The effect of different inputs to the model were examined and their significance assessed using Monte Carlo simulation. The Base Estimates were the most important determinant of exposure in the model. The sources of variability in the measured data were examined, including the effect of having censored data and the between and within-worker variability. The sources of uncertainty in the exposure estimates were analysed and consequential improvements in exposure assessment identified. Monte Carlo sampling was also used to examine the uncertainties and variability associated with the tanker drivers' exposure assessment, to derive an estimate of the range and to put confidence intervals on the daily mean exposures. The identified uncertainty was less than the variability associated with the estimates. The traditional approach to exposure estimation typically derives only point estimates of mean exposure. The approach developed here allows a range of exposure estimates to be made and provides a more flexible and improved basis for risk assessment.

On August 31, 1992, Quality Printing Circuits, a circuit board manufacturing plant in Phoenix, Arizona, burned to the ground. The fire lasted approximately eight hours, creating a thick, black smoke that blew into the surrounding community. Emergency evacuation was erratic and since no air samples were taken during the fire, community exposure levels were unknown. Immediately afterwards, residents reported health problems but government studies on the community were unable to link reported health problems and the fire. Eight months after the fire, a local advocacy group performed a health study on the community. The 690 people surveyed reported symptoms such as asthma, blurred vision, vomiting, hair loss, rashes, and extremity numbness. The survey was never analyzed and the case was closed. Community members continued to report health problems and five years after the fire, the US Environmental Protection Agency reopened the case. They performed two sampling studies but results found that chemical levels were below allowable exposure levels. This thesis contains three chapters that investigate the political, health, and scientific issues related to the QPC fire. The scientific chapter uses the EPA's ISCST3 dispersion model and a mixed-box model, to approximate community exposure concentrations and compare them to allowable human exposure levels. Results of the ISCST3 model show that four (hydrogen chloride, polycyclic aromatic hydrocarbons, Acrolein, and naphthalene) of the twenty chemicals modeled were above government allowable concentrations. Inhalation exposure to these chemicals causes similar symptoms as those reported by residents. The health-focused chapter characterized health symptoms reported in the 1993 health survey. Results found that symptoms experienced by residents were similar to those documented in other studies of exposure to chemical smoke. The study also found that residents living closest to QPC reported a greater number of symptoms than residents living further away. The political chapter analyzed the debate as to whether QPC officials and government agencies took the steps needed to protect the exposed community during and after the QPC fire. What became evident was that a significant conflict existed between the interests of residents involved in the QPC fire and the government agencies responsible for protecting them. / Graduation date: 2004

The public controversy over possible health hazards from radioactive fallout from atomic bomb testing began in 1954, shortly after a thermonuclear test by the United States spread fallout world wide. In the dissertation, I address two of the fundamental questions of the fallout controversy: Was there a threshold of radiation exposure below which there would be no significant injury? What was the role of a responsible scientist in a public scientific debate? Genetics and medicine were the scientific fields most directly involved in the debate over the biological effects of radiation. Geneticists' prewar experiences with radiation led them to believe that there was no safe level of radiation exposure and that any amount of radiation would cause a proportional amount of genetic injury. In contrast to geneticists, physicians and medical researchers generally believed that there was a threshold for somatic injury from radiation. One theme of the dissertation is an examination of how different scientific conceptual and methodological approaches affected how geneticists and medical researchers evaluated the possible health effects of fallout. Geneticists and physicians differed not only in their evaluations of radiation hazards, but also in their views of how the debate over fallout should be conducted. A central question of the fallout debate was how a responsible scientist should act in a public policy controversy involving scientific issues upon which the scientific community had not yet reached a consensus. Based on their assumption that any increase in radiation exposure was harmful, most geneticists believed that they had a responsibility to speak out publicly about the deleterious effects of radiation. Physicians, who believed in the likelihood of a threshold for significant radiation-induced injury, generally adopted the opposite view. They believed that public discussion of possible, but improbable, radiation hazards was irresponsible because it risked creating irrational public fear of radiation exposure. In my dissertation, I examine how the different positions of geneticists and physicians over what constituted responsible public scientific debate affected the rhetoric of the controversy, as well as the implications of the debate in matters of politics and policy. / Graduation date: 2004

The National Council of Radiation Protection and Measurements Report No. 49, originally issued on September 15, 1976, has been the primary design guide for diagnostic x-ray structural shielding in the United States. To further protect the public from various areas of medical radiation exposure, NCRP issued Report 116 in 1987 to decrease the public exposure limits. These new limits used in conjunction with NCRP 49 to determine shielding requirements for diagnostic radiological rooms can be shown to over-shield based on current technologies and protocols. This paper explores the NCRP conservative assumptions that physicists specifying barrier requirements for diagnostic x-ray facilities normally utilize. These evaluated assumptions, which are incorporated in the methodology and attenuation data presented in NCRP Report 49 formulas, include relatively high single kVp's, a "one size fits all" workload default, and the lack of attenuation factors by the patient, the wall, and the film. In essence, an analysis of the conservative nature of NCRP 49 is demonstrated. An example of Primary and Secondary Shielding Methodology utilizing NCRP 49 and NCRP 116 dose limits is provided as well as the cost factors associated with the results. These examples are further evaluated using a Monte Carlo software program. In addition, an analysis of actual current radiographic conditions in an imaging room is performed. This is done to determine first, the actual mA utilized for specific exams; secondly, the actual mA-min weekly workload; and thirdly, the tangible exams performed per week in small and large medical facilities. Based on the information and analysis presented, this paper concludes that the formulas for NCRP 49 and NCRP 116 need to be reexamined. Furthermore, this paper also demonstrates once again that NCRP 49, utilizing NCRP 116 dose limits is extremely conservative. / Graduation date: 2004

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

In the United States, falls are the leading cause of unintentional death with one of every three people 65 years and older falling each year. Falls account for approximately 95% of hip fractures among older adults and falls to the side predominate hip fracture related falls in this population. However, risk factors for side and frequent falls are poorly understood. Furthermore, few data exist to explain differences in bone mineral density among older postmenopausal women. In particular, data regarding the timing of hormone replacement therapy (HRT) among older women is scarce. In the first aim of this dissertation, we examined changes in mobility and balance-related risk factors for side falls as well as differences in these risk factors according to fall status in a population of 107 independent, elderly women (>70 yrs), who were followed over 2 years. We found hip abduction strength decreased (p<.001) in all subjects, with side-fallers exhibiting weaker hip abduction strength (p=.008), greater sway velocity (p=.027), and slower performances on the tandem walk (p=.039) and Get Up and Go (p<.001) compared to non-fallers. For the second study, in the same population, we examined 2-year changes in balance self-efficacy (BSE) and the relationship of BSE to side fall risk factors and falls incidence. Results showed BSE at baseline was predictive of Get Up and Go, hip abduction strength and tandem walk at follow-up (p<.008), but that BSE decreased only among the non-fallers (p=.013). In the third study, we examined 3-yr hip bone mineral density (BMD) changes in women with distinct hormone replacement therapy (HRT) profiles: 1) no hormone replacement therapy (N0HRT), 2) HRT continually since menopause (Continual), 3) HRT begun 10 years after menopause (Late), 4) HRT initiated within 5 years (New), and compared the change in BMD of the hip across HRT groups. Only the NoHRT group lost bone over the 3 years (p=.014). We also assessed BMD of the lateral spine across levels of estrogen use in a sub-sample of participants and found long-term HRT users had significantly higher lateral spine BMD (p=.041) compared to women who had never been on HRT. / Graduation date: 2003