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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

Evaluation of occupational and environmental exposure to mercury among dental amalgam and chlor-alkali workers in Pakistan and among small-scale gold miners in Cambodia, Burkina Faso, Chile and Sudan

Elgazali, Abdelkarem Abdullah Saad January 2013 (has links)
Mercury is a well-known toxic element which can be taken up into the human body in different forms, causing particular harm to the nervous system. Despite this fact, it is still used widely in industrial processes, with chlor-alkali electrolysis one of the most extensive pollution sources of mercury. Though most industries today use mercury-free processes, some chlor-alkali factories still use the mercury process, especially in less developed countries. In addition, small-scale gold mining activity remains the largest global mercury consumer and continues to increase the use of mercury given the upward trend in the price of gold. The aim of this study is to investigate the level of mercury exposure to workers in chlor-alkali factories and a dental hospital in Pakistan. In addition, it is to investigate the level of mercury exposure to miners in small-scale gold mining areas (AGM) in Cambodia, Burkina Faso and Chile. Both investigations were undertaken within the United Nations Environment Programme (management of mercury waste). Within this study, the investigation of mercury exposure to miners was conducted in four small-scale gold mining areas in Sudan. A simple analytical digestion and extraction method for total mercury (T-Hg) analysis in biological and environmental samples with fast sample preparation procedure using CV-AFS and ICP-MS was developed. In addition, for SSIDMS-GC-ICP-MS analysis, the alkaline microwave assisted extract method and acid leaching assisted extract method for Me-Hg analysis in biological samples (hair samples) were developed. These developed analytical methods were used to evaluate the levels of occupational and environmental exposure in the selected areas with Hg hot spots. For Pakistan, to establish chlor-alkali workers' Hg exposure, hair and nail samples of 23 individuals were investigated for total mercury. Within this cohort, 15 individuals had hair total mercury levels above 100 μg g-1, thus exceeding the WHO regarded "safe limit" of 2 μg g-1 in hair Hg by a factor of 50. Several samples showed hair T-Hg levels above 1000 μg g-1, suggesting extreme exposure to Hg. These levels must be regarded as extremely toxic, assuming that these Hg levels in hair correspond to Hg ingestion. In the process of chlor-alkali electrolysis, volatile mercury compounds are formed, including Hg0 and other volatile mercury compounds. These volatile species can adsorb on surfaces, and it is suggested that besides uptake by inhalation, Hg compounds may be adsorbed on keratinous hair and nail material. The investigation of single hairs with synchrotron techniques showed that most of the mercury is found on the outside of the hair, but certain amounts were also metabolised. Adsorption experiments with Hg0 and HgCl2 were conducted to assess the sorption characteristics of these volatile Hg compounds. The results showed that both mercury species' vapour pressures are related to the adsorption of volatile mercury compounds. HgCl2 has a higher vapour pressure and is about two orders of magnitude higher in adsorption than Hg0, suggesting that the chlor- alkali workers have been exposed to HgCl2 in the chlor-alkali plant. Finally, mercury speciation was performed on the ICL chlor-alkali hair samples which showed that almost all mercury was in inorganic form. The source of Me-Hg in the hair seems to be dietary, as no correlation between inorganic and Me-Hg in the hair could be found. The highest value for Me-Hg is around 5.0 μg g-1, which is in the range of concentration found in communities with a high fish diet. Finally, the high mercury result suggests that the mercury (Hg) in the hair samples from workers in the ICL chlor-alkali is from external adsorption rather than from inhalation and was subsequently incorporated into the hair. Nevertheless, in the second chlor-alkali factory in Pakistan (SCL chlor-alkali factory), the average total mercury concentrations in hair and nails are low and almost at control level. However, in this factory, mercury cell technique was phased out a few years ago. This factory now uses membrane cell instead of mercury cell technology. For the dental hospital sector in Pakistan, inorganic mercury concentrations were 6 times higher than Me-Hg concentration in hair samples i.e. Me-Hg and In-Hg in hair accounted for, on average 14.13 % and 85.87 % of T-Hg respectively for these dental workers. However, the high mercury levels in hair could be due to exposure to amalgam. For AGM areas, the T- Hg concentration (μg g-1) in hair samples from AGM miners in Burkina Faso (mean, 3.80 μg g-1) were compared with Cambodian AGM miners and Sudan AGM miners (mean 5.78 and 5.04 μg g-1 respectively). This mean value was significantly lower than that found in the hair of miners in the Cambodia and Sudan AGM areas. This indicates that the AGM miners in these countries are exposed to mercury vapour during the AGM processes. Otherwise, the AGM workers in Cambodia are also exposed to considerable amounts of methylmercury (Me-Hg) through seafood consumption that is a more toxic Hg form. However, the long-term implications for water bodies such as River Nile and Red Sea ecosystems, fish as food and irrigation water use (e.g. for rice paddies) may be disastrous. Therefore, further investigation of Hg analysis in hair and soils should be conducted in these areas to analyse the risk of Hg contamination.
162

Port state control and its implication on ship safety

Li, Stephen Yiu Kwong January 2002 (has links)
Over the past twenty years a growth in sub-standard shipping has been observed. The thesis identifies the causes of this growth. It then identifies Port State Control (PSC) as a measure evolved by some states, with the purpose of removing sub-standard shipping from their waters, and thereby improving maritime safety and the protection of the environment. The purposeo f this programmeo f researchi s to assessth e effectivenesso f PSC in achieving its purpose. An eclectic research methodology has been adopted which first considers, in depth, the global and regional context in which PSC functions. Taking the Port of Hong Kong as an example, the study then reviews how PSC operates in practice. Shipping casualty data is examined to test the merits of targeting ships for PSC inspection. Finally the expert opinion of both official and wider marine communities in Hong Kong is sampled in order to form an overall view on the effectiveness of PSC. The research reveals considerable agreement between all parties that PSC, in general is achieving its purpose. It also recognizes that PSC should only be a "second line of defence" in combating sub-standard shipping. The first line remains Flag State enforcement of standards, accompanied by wider development of a safety culture in the shipping industry
163

Non-legitimate illness, embodied experience and the moral career : the case of ME/CFS

Collett, Tracey Jane January 2002 (has links)
The condition known as myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) is an illness of unknown aetiology which affects over 150 000 persons in the UK. Whilst the cause of the condition is the subject of intense medical debate, the official view is that it is a form of atypical depression or somatisation disorder. This view is at odds with the views of many sufferers who claim that ME/CFS is a pathological disease that renders them severely incapacitated. Sufferers' maintain that, because their condition is regarded as a minor, psychological illness, its' severity is not recognised. Thus, rather than being granted assistance, their appeals for help are often met with accusations of malingering or hypochondriasis. This, they argue, results in significant marginalisation. In short, sufferers' state that they experience bodily change that is profound and disabling, however, their claims to be `really ill', are ignored. ME/CFS is one of a number of conditions whose meanings are contested. Other such conditions include Gulf war syndrome, repetitive strain injury, organophosphate poisoning, and multiple chemical sensitivity. These conditions are worthy of sociological study because they `make visible' the way that social definitions of illness impact on the experience of illness. The data for this thesis is derived from an empirical study of sufferers' experiences of ME/CFS. Using both qualitative and quantitative research methods, the study explores the embodied experience of ME/CFS and the illness careers of sufferers. The findings of the study are analysed in the light of the sociological literature on `the cultural expectations surrounding illness', `embodiment' and `the experience of illness'. Whilst the past literature has either focused on `the cultural expectations surrounding illness' or `the experience of illness', this thesis brings together the two areas and uncovers the complex set of relations and pathways that emerge when ideas about illness clash. The findings have implications for the sociological understanding of the illness experience. They are particularly relevant because, as the chronically ill population expands, there is an increasing emphasis on individual responsibility for illness. Thus, whilst contested illnesses are a blatant example of what happens when sufferers' are held accountable for being ill, the findings have implications for the experience of all chronic illness.
164

A study of the effect of tunnel aspect ratio on control of smoke flow in tunnel fires

Bakar, M. Z. Abu January 1999 (has links)
No description available.
165

Promoting safety in the work environment: the role of internal marketing

30 April 2009 (has links)
M.Comm. / The process of creating a safe working environment for all has proved to be one of the most complex facets within an organisation. This may be attributed to the fact that there are so many elements involved in ensuring occupational safety. Not only has the individual employee a responsibility towards safety, including his or her attitude and risk-taking behaviour, but also does the organisation contribute towards this hazard-free environment in providing a culture where safety is regarded as a priority or not. Furthermore, the role of internal marketing will have an impact on whether employees will buy into the concept of occupational safety. Internal marketing may be conveyed through management and how they communicate the importance of a safe workplace through elements such as training and motivation. From the above it is clear that both individual and organisational factors play a crucial part in ensuring a hazard-free environment. The challenge is to link these factors together ensuring cooperation from both the employee and employer. If the idea of a safe working environment is not effectively marketed inside the organisation, the factors involved will be negatively influenced, leading to an unsuccessful implementation of safety in the organisation. The purpose of this research study is to determine whether occupational safety can be promoted successfully through internal marketing. Unless there is an understanding of all the concepts related to a safe working environment, the benefits as a result of the implementation of occupational safety will not be fully grasped.
166

Hexamethylene Diisocyanate Homopolymer and Monomer Exposure Assessment and Characterization at an Automobile Manufacturer in the United States

Sivaraman, Karthik R. 18 August 2016 (has links)
<p> A variety of paint products are used for their aesthetic and anti-corrosive properties. Isocyanates are consistently found in automobile paint products, particularly in clear coat polyurethane products. Clear coat is typically sprayed via pressurized air by means of an auto-spray robot. In clear coat repair situations, manual, air-powered spray guns are used, and manual spray Operators administer the clear coat material. The isocyanates are a primary anti-corrosive agent in polyurethane products. The Occupational Safety and Health Administration (OSHA) has not established a Permissible Exposure Limit (PEL). The National Institute for Occupational Safety and Health (NIOSH) and American Conference of Governmental Industrial Hygienists (ACGIH) have set Recommended Exposure Limit (REL) and Threshold Limit Value (TLV), respectively. NIOSH recommends a 0.005 parts per million (ppm), 10-hour Time Weighted Average (TWA), and a ceiling exposure of 0.020 ppm in a 10 minute period. Similarly, ACGIH recommends a 0.005 ppm, 8 hour TWA. </p><p> Automobile manufacturers use clear coats in a variety of ways. Some may use clear coats with blocked isocyanates, or isocyanates that are completely reacted, and others may use clear coat products that allow isocyanates to be liberated during an application, baking, and curing process. The research objective of this study was to characterize exposure, focusing on a single manufacturer&rsquo;s use of isocyanate-containing clear coats in their Paint Department. A newly evaluated medium (ISO 17734) using di-n-butylamine as a derivative agent, in a denuder tube, was selected instead of NIOSH methods 5521, 5522, and 5525. The ISO evaluated medium was selected to reduce secondary hazard exposure to toluene in impingers. Second, a medium developed by SKC, Inc., called ISO-CHEK&reg;, was not selected because of the short collection time, sensitivity of the medium after collection, and storage and shipping requirements for analysis. </p><p> Sampling took place over two days, one day for manual spray operations with 2 personal samples from Operators, and 4 area samples collected, and the second day for auto-sprayer Inspectors with 4 personal samples collected. The samples were then analyzed for hexamethylene diisocyanates (HDI) monomer and homopolymer species. The 0.005 ppm, 10 hour TWA; the 0.020 ppm ceiling limit (10 minutes); and the 0.005 ppm 8-hour TWA TLV were not exceeded on either day of sampling. Neither the area nor the personal samples exceeded the 10 hour TWA, ceiling limit, or TLV. In fact, the results had to be recalculated in to parts per billion (ppb). The average exposure for manual spray Operators was 0.052 ppb for the homopolymer, and 0.024 ppb for the monomer species. For auto-spray Inspectors, the average was 0.053 ppb for the homopolymer component and 0.021 ppb for the monomer species. Though the average isocyanate concentration was similar for both Operators and Inspectors, the averages are still below REL and TLV recommendations. These data provided preliminary information regarding the exposure to isocyanates from clear coat use, and also provide context for future evaluation of isocyanate use at this automobile manufacturer. The low concentration of isocyanates could indicate working ventilation systems, liberation of isocyanate species to non-hazardous forms, or low volatilization of isocyanates from the clear coat.</p>
167

Literacy and the comprehension of public safety signs, with and without written aids.

Howell, Lindsay 28 January 2009 (has links)
The aim of this study is to determine the comprehension levels of safety signs with and without written aids among South African workers. Numerous studies on warnings and safety have identified certain factors that can influence the effectiveness of safety communications such as, individuals’ behavioural responses to safety messages as well as the impact of design features on safety information (Kline, Braun, Peterson & Silver, 1993). However, little research has explored the role that literacy plays in interpreting safety information, specifically in developing countries such as South Africa where illiteracy is common. Sixty structured interviews were conducted at the Johannesburg General Hospital, a locale which essentially everyone has equal public access to. Twelve randomly ordered safety signs were presented to participants upon which they were required to describe what they understood each safety sign meant. Varied education and literacy levels were evident however the majority of the sample had only received some level of high school education. Interestingly, of the twelve safety signs chosen for this study, only three safety signs (SS1, SS4 and SS7) were ‘acceptable’ according to ANSI Z535.3 (1991) and ISO’s 3864 (1984) criteria. Furthermore, results from this study suggest that there is a relationship between one’s level of education and the understanding of certain safety signs.
168

An investigation into the factors affecting the strength of pillars in South African coal mines

Madden, Bernard John 21 February 2011 (has links)
PhD, Faculty of Engineering, University of the Witwatersrand
169

A method to determine the effectiveness of the application of the investigation process for electrical incidents

Jooma, Zarheer January 2017 (has links)
A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2017 / This study examines the application of the investigation process in industry to reduce electrical arc flash incidents. Literature indicates that three streams (policies, completed investigations and investigators) influence the application of the investigation process; however, these are traditionally analysed independently without examining the dynamic influences between them. This study combines and analyses those dynamic interactions, and testing at a steel plant demonstrates that this approach allows industry to identify site specific deficiencies. The investigation process requirements, identified in literature, were used to qualitatively and quantitatively analyse the three streams. The results were interpreted using triangulation. Deficiencies around disseminating reports and using experienced investigators were identified. These plant specific deficiencies are an improvement from generic findings in literature. This study contributed to knowledge in the field of incident investigations by proposing a holistic approach that is operationally ready, and identifies deficiencies specific to the industry in which it is used. / MT 2018
170

A resource unit for teaching safety in an elementary school camp without a waterfront

Unknown Date (has links)
"Emphasis was laid upon the need for safety procedures for the school camp by the Consultant of Health and Safety Education of the Florida State Department of Education, Tallahassee, Florida, who suggested the topic for this study. Therefore, it is the purpose of this study to construct a resource unit on camping safety for elementary school teachers"--Introduction. / Typescript. / "August, 1950." / "Submitted to the Graduate Council of Florida State University in partial fulfillment of the requirements for the degree of Master of Science under Plan II." / Includes bibliographical references (leaves 40-41).

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