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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.
61

Chemical emissions from building structures : emission sources and their impact on indoor air / Kemiska emissioner från byggnadskonstruktioner : källor till emissioner och deras påverkan på inomhusluften

Glader, Annika January 2012 (has links)
Chemical compounds in indoor air can adversely affect our comfort and health. However, in most cases there is only a limited amount of information available that can be used to assess their health risk. Instead the precautionary principle is often applied, i.e. efforts are made to ensure that the concentrations of pollutants are kept at a minimum when constructing new buildings or conducting renovations by using low-emitting building materials. Today, when investigating buildings in order to solve indoor air quality problems, volatile organic compounds (VOCs) are sampled in the air within rooms. The chemical composition of indoor air is complex and there are many sources for the chemicals present. The potential for emissions from sources in hidden spaces such as wall cavities is poorly understood and little information exists on the toxic potential of chemical releases resulting from moisture-related degradation of building materials. Most of the non-reactive VOCs that have been detected in indoor air in field studies and from building products are not believed to cause health problems. However, reactive compounds and chemical reaction products have the potential to negatively influence our comfort and health even at low concentrations. Even though the impact of chemical compounds on health is unclear in many cases, they can be used to identify technical problems in buildings. When a building is investigated, the air inside building structures could be sampled. This method would eliminate emissions from sources other than the construction materials and the samples would contain higher levels of individual compounds. The aims of this work was to identify emissions profiles for different types of building structures, to see if the emission profiles for moisture damaged and undamaged structures differed, and to determine whether any of the emissions profiles for specific structures also could be found in indoor air. Technical investigations and VOC sampling were performed in 21 different buildings with and without previous moisture damage. Seven of the buildings were investigated in the years 2005-2006 (study 1) and fourteen in the years 2009-2010 (study 2). In study 1, sixty samples were analyzed by PCA at the chemical group level (18 chemical groups, i.e. aldehydes, ketones etc). 41 % of all identified chemical compounds belonged to the hydrocarbon chemical group. The second largest chemical groups, each of which accounted for 5-10 % of all identified compounds, were alcohols, aldehydes, ketones, polyaromatic hydrocarbons (PAHs) and terpenes. The results indicated that one of the main factors that determined the emissions profile of a building structure was the materials used in its construction. Notably, concrete and wooden structures were found to have different emissions profiles. The sum of VOC (TVOC) concentrations for all 241 samples from both study 1 and study 2 was used to compare total emissions between different building elements (ground and higher floors, external walls and roof spaces). Most building elements exhibited relatively low emissions compared to concrete ground floors, which generally had higher TVOC emissions. Emissions from both polystyrene insulation and PVC flooring could be identified in concrete ground floors and were the main cause for the higher emissions found in these structures. Profiles for wood preservatives such as creosote and pentachlorophenol were also identified in external walls. The emission profiles found in the structures could not be identified in the indoor air in the adjacent rooms, although individual compounds were sometimes detected at low concentrations. Our results showed that the main factors influencing emissions in building structures were the construction materials and the nature of the building element in question. Because of difficulties with finding active water damage at the times of sampling and because of sampling inside closed building structures with old dried-out moisture damages, the field method used in this work was unsuitable for identifying differences in emission profiles between moisture damaged and undamaged structures. It will thus be necessary to investigate this difference in a laboratory where the precise composition of all tested structures is known, a range of RH values can be tested and the accumulation of emissions can be followed. / Kompetenscentrum Byggnad - Luftkvalitet - Hälsa 2 (KLUCK 2)
62

Bradford Non-Lethal Weapons Research Project (BNLWRP). Research Report No. 6.

Davison, N., Lewer, N. January 2004 (has links)
yes / New non-lethal technologies (weapons and delivery systems) continue to make the news, both for their civil and military applications. Technologies which were considered to be in the realm of science fiction a few years ago, are now beginning to undergo field trials or, in some cases, are being deployed with police and soldiers on active service. As this, and our previous reports have highlighted, the development of acoustic weapons (Long Range Acoustic Device) and microwave weapons (Active Denial System) have proceeded rapidly as have advances in robotic, unmanned vehicles for the delivery of both lethal and non-lethal weapons. We repeat our concern that there is a danger of these new non-lethal technologies being `rushed¿ into service (1) without thorough testing for harmful health effects, (2) without a deeper consideration of civil and human rights, (3) without full discussion of their impact on arms control treaties and conventions, and (4) without further study of their social and cultural impact. Since many such weapons will have a rheostatic capacity along the non-lethal to lethal continuum, it is important that weapons developers and manufacturers, and those charged with the responsibility of using them, are held clearly accountable and have transparent rules of engagement. Of particular concern are a new generation of biological and chemical weapons. With respect to the health impact, NATO has a panel working on NLW human effects, the Human Factors and Medicine (HFM) Panel 073, which is due to report later this year (2004) on the Human Effects of Non-Lethal Technologies.1
63

Från Barndom till Ålderdom: Multipel-aktörsansats för hälsa och välbefinnande genom livscykel- perspektiv från barnläkares erfarenheter / From Childhood to Old Age: Multi-actor approach to health and well-being through a life course perspective from pediatrician's experiences

Hemmenbach, Annkatrin January 2024 (has links)
Bakgrund: Att undersöka äldres hälsa och välbefinnande med ett livscykelperspektiv ger insikter i hur tidiga livserfarenheter formar välbefinnandet senare i livet, vilket är det övergripande ramverket för denna empiriska studie. Studien betonar vikten av att förstå de komplexa faktorer som påverkar hälsa och välbefinnande hos äldre över livet från ett folkhälsoperspektiv. Med en ökande åldrande befolkning är det avgörande att adressera dessa faktorer för att främja hälsosamt åldrande. Studien utforskar äldres hälsa och välbefinnande genom ett livscykelperspektiv med en unik ansats, belyser hur samverkan mellan familjen, samhället och vetenskapen kan främja detta, med barnläkares perspektiv som en central komponent för att främja hälsa och välbefinnande under livets olika faser. Syfte: Syftet med denna studie är att undersöka sambanden mellan tidiga livsfaser och hälsa samt välbefinnande i äldre ålder. Genom att utforska hur barnläkares expertis inom pediatrisk utveckling och hälsa kan bidra till förståelsen av långsiktiga hälsoeffekter orsakade av barndomens förhållanden. Metod: För att besvara studiens syfte användes en kvalitativ metod med induktiv ansats. Datainsamlingen genomfördes genom semistrukturerade intervjuer med fem äldre barnläkare i Sverige som har minst två decenniers erfarenhet av klinisk verksamhet. Deltagarna valdes ut genom målinriktat urval. Den insamlade datan analyserades med en kvalitativ innehållsanalys med inslag av Grounded Theory. Resultat: Studien identifierar fyra huvudkategorier: Familjens och samhällets roll i barnets utveckling och hälsa, Reflektion över Barnets Utveckling och Livscykelperspektiv, Betydelsen av Tidiga Insatser och Förändring, samt Vetenskapens Ansvar i Barnets Utveckling och Hälsa. Resultaten av studien visar på barnläkares betydelsefulla insikter om livscykelperspektivet och understryker behovet av en multipel-aktörsansats genom att involvera både familjen, samhället och forskarsamhället i processen. Slutsats: Äldre barnläkares perspektiv på livscykelperspektivet ger en unik inblick i hur de sambandet barnets hälsa och välbefinnande i senare skeden av livet. Det understryks en vidgad förståelse av barns utveckling och hälsa med fokus på familjens generationsöverskridande interaktioner och samverkan. Vidare föreslås att en holistisk och multipel-aktörsansats som involverar familjen, samhället och forskargemenskapen är avgörande för att skapa gynnsamma förhållanden för barn och individer. / Background: Investigating the health and well-being of the elderly through a life cycle perspective provides insights into how early life experiences shape well-being later in life, which is the overarching framework for this empirical study. The study emphasizes the importance of understanding the complex factors affecting the health and well-being of older people over a lifetime from a public health perspective. With an increasing aging population, it is crucial to address these factors to promote healthy aging. The study explores the health and well-being of older people through a life cycle perspective with a unique approach, highlighting how the collaboration between family, society, and science can promote this, with the perspective of pediatricians as a central component for promoting health and well-being throughout the various stages of life. Aim: The purpose of this study is to investigate the connections between early life stages and health and well-being in older age. By exploring how pediatricians’ expertise in pediatric development and health can contribute to understanding the long-term health effects caused by childhood conditions. Method: To answer the study’s purpose, a qualitative method was used with an inductive design. Data collection was collected through semi-structured interviews with five senior pediatricians in Sweden who have at least two decades of clinical experience. Participants were selected through purposeful sampling. A qualitative content analysis, with elements of Grounded Theory was used to analysis the data. Results: The analysis resulted in four main categories: The Role of Family and Society in Child Development and Health, Reflection on Child Development and Life Cycle Perspective, The Importance of Early Interventions and Change, and The Responsibility of Science in Child Development and Health. The results of the study highlight the significant insights of pediatricians on the life cycle perspective and underscore the need for a multi-actor approach by involving both the family, society, and the research community in the process. Conclusion: The perspective of older pediatricians on the life cycle perspective provides a unique insight into how they connect child health and well-being in later stages of life. An extended understanding of child development and health with a focus on intergenerational family interactions and collaboration is emphasized. Furthermore, it is suggested that a holistic and multi-actor approach involving the family, society, and the research community is crucial to create favourable conditions for children and individuals.
64

Avaliação do risco de mortalidade por leucemia, neoplasias do sistema nervoso central e esclerose lateral amiotrófica associado à exposição residencial a campos magnéticos: um estudo do tipo caso-controle no Município de São Paulo / Evaluating the risk of leukemia, brain cancer and amyotrophic lateral sclerosis deaths in relation to magnetic field exposure: a case-control study in the city of São Paulo

Souza, Izabel Oliva Marcilio de 03 March 2009 (has links)
O presente trabalho teve como objetivo avaliar o risco de óbito por leucemia, neoplasias do sistema nervoso central e esclerose lateral amiotrófica em adultos em relação à exposição a CM, no Município de São Paulo. Foi realizado um estudo do tipo caso-controle populacional envolvendo 6224 sujeitos. Casos e controles foram extraídos da base de dados do PROAIM, e foram pareados por sexo, faixa etária e distrito administrativo de residência. Foram considerados casos todos os óbitos pelos desfechos específicos, em adultos com 40 anos ou mais, residentes no Município de São Paulo, ocorridos entre 2001 e 2005. Controles foram constituídos por óbitos por todas as outras causas ocorridos no mesmo período. A exposição foi avaliada de acordo com a distância das residências dos sujeitos para a linha de transmissão (LT) mais próxima. Foi encontrado um aumento do risco de óbito por leucemia entre os indivíduos que moravam mais próximo às LT, com OR ajustado de 1,8 (IC 95%: 0,8 - 4,3) e 2,5 (IC 95%: 1,0 - 7,2) entre os sujeitos que moravam a 50 m e entre 50 e 100 m das LT, respectivamente, em relação aos que moravam a mais de 400 m. / This work aimed at evaluating the risk of death by leukemia, brain tumor and amyotrophic lateral sclerosis in adults in relation to magnetic field exposure, in the city of São Paulo. A population-based case-control study was held, and 6224 subjects were enrolled. Cases and controls were selected from the PROAIM database, and were matched by sex, age and district of residence. Cases were all deaths ocurred between 2001 and 2005 by the specific causes, ocurring in adults 40 years and older, living in the city of São Paulo. Controls were selected from all other deaths ocurred at the same period. Exposure to magnetic fields was accessed according to the distance of the dwelling to the closest transmission line (TL). The risk of death by leukemia was elevated within the subjects living closest to the TL, with an adjusted OR of 1,8 (CI 95%: 0,8 - 4,3) and 2,5 (CI 95%: 1,0 - 7,2) for people living within 50 m and within 50 to 100 m away from the TL, respectively, in relation to people living at 400 m or further.
65

Effekter av fysisk aktivitet vid diabetes typ 2 : En litteraturöversikt / Effects of physical activity for diabetes type 2 : An integrative literature review

Levin, Charlotte, Mariz Ljunggren, Jaqueline January 2017 (has links)
Inledning: Diabetes typ 2 är en metabol sjukdom som har ökat i hela världen. Diabetes medför stora hälsoproblem som kan leda till förtidig död och funktionshinder. Fysisk aktivitet är en faktor som kan förändra diabeteskomplikationer och förbättra människors möjlighet att hantera symptomen av diabetes. Syftet med litteraturöversikten är att identifiera effekterna av fysisk aktivitet vid diabetes typ 2 bland vuxna. Metod: Denna studie är en litteraturöversikt där tio originalartiklar har använts för att genomföra denna studie och fyra teman framkom som förklarar effekten av fysisk aktivitet vid diabetes typ 2. Resultat: Olika träningsform såsom aerob- kombinerad- och styrketräning samt effekt av medicinering vid diabetes typ 2 visar att diabetes kan förbättras genom fysisk aktivitet. Diskussion: Fysisk aktivitet anses som viktigt för att bekämpa symptom av diabetes typ 2. Olika former av träning förbättrar diabetes typ 2. Mer forskning behövs för att bidra till kliniska rekommendationer. / Introduction: Diabetes type 2 is a metabolic disease that has increased all over the world. Diabetes causes huge health problems that lead to premature death and disabilities. Physicalactivity is a factor that can improve diabetes complications and ameliorate the management of the symptoms related to diabetes. The aim of this literature review is to identify effects of physical activity in diabetes type 2 among adults. Methods: This study is a literature review where ten original articles were used to carry out this study and five themes were developed to explain the effects of physical activity in diabetes type 2. Results: Different types of training such as aerobic training, combined training, resistance training and also the effect of medicine showed that diabetes type 2 can be improved through physical activity. Discussion: Physical activity is important to fight the symptoms of diabetes type 2. Different types of training improve in various ways diabetes type 2. More researches are needed to contribute to clinical recommendations.
66

Recreational Exposure To Freshwater Cyanobacteria: Epidemiology, Dermal Toxicity And Biological Activity Of Cyanobacterial Lipopolysaccharides

Stewart, Ian Unknown Date (has links)
Cyanobacteria are common inhabitants of freshwater lakes and reservoirs throughout the world. Under favourable conditions, certain cyanobacteria can dominate the phytoplankton within a waterbody and form nuisance blooms. Case reports and anecdotal references dating from 1949 describe a range of illnesses associated with recreational exposure to cyanobacteria: hay fever-like symptoms, pruritic skin rashes and gastro-intestinal symptoms (the latter probably related to ingestion of water) are most frequently reported. Some papers give convincing descriptions of allergic responses to cyanobacteria; others describe more serious acute illnesses, with symptoms such as severe headache, pneumonia, fever, myalgia, vertigo and blistering in the mouth. A U.S. coroner recently found that a teenage boy died as a result of accidentally ingesting a neurotoxic cyanotoxin from a golf course pond; this is the first recorded human fatality attributed to recreational exposure to cyanobacteria. One of the main public health concerns with exposure to freshwater cyanobacteria relates to the understanding that some blooms produce toxins that specifically affect the liver or the central nervous system. The route of exposure for these toxins is oral, from accidental or deliberate ingestion of recreational water, and possibly by inhalation. Cyanobacterial lipopolysaccharides (LPS) are also reported to be putative cutaneous, gastrointestinal, respiratory and pyrogenic toxins. The aims of this project were to enhance the understanding of public health issues relating to recreational exposure to cyanobacteria by conducting epidemiological and laboratory-based toxicology studies. A prospective cohort study of 1,331 recreational water users was conducted at various sites in southern Queensland, the Myall Lakes area of New South Wales, and central Florida. The study design sought to make improvements over previously published epidemiological studies, in that an unexposed group was recruited from cyanobacteria-free waters, cyanobacterial toxins were measured in site water samples, and respondents were asked to rate the severity of reported symptoms. This study has shown an increased likelihood of symptom reporting amongst bathers exposed to high cyanobacterial cell density (measured by total cell surface area) compared to those exposed to low cyanobacteria-affected waters. Mild respiratory symptoms appear to be the predominant symptom category. A clinical dermatology study to examine delayed-contact hypersensitivity reactions to cyanobacterial extracts was conducted. The study groups were 20 patients presenting for diagnostic skin patch testing at the Royal Brisbane Hospital's dermatology outpatient clinic; a convenience sample of 20 individuals was recruited from outside the hospital as a control group. One patient developed unequivocal reactions to several cyanobacteria extracts, with no dose-response pattern seen, indicating that the reactions were allergic in nature. A mouse model of delayed-contact hypersensitivity, the mouse ear swelling test, has demonstrated that the purified toxin cylindrospermopsin, a highly water-soluble compound, is capable of producing cutaneous injury. Encrusting lesions were seen on abdominal skin during the induction phase of these experiments. Delayed-contact hypersensitivity reactions were also demonstrated with this toxin. LPS from two non-axenic cyanobacterial samples - Cylindrospermopsis raciborskii and Microcystis aeruginosa - were extracted and purified. Thermoregulation studies were performed using a mouse model of rectal temperature measurement. Separate groups of mice were injected with these LPS extracts at two dose levels. Thermoregulation studies were also conducted with purified cyanobacterial toxins: microcystin-LR and cylindrospermopsin and anatoxin-a; cyanobacterial LPS samples purified by collaborators in Adelaide were also investigated for thermoregulation potential. These experiments have shown that the LPS extracts are weakly active when compared with responses to much lower doses of Escherichia coli LPS. Cylindrospermopsin also produces hypothermic responses in mice - comparable to pyrexia in larger mammals - although at a later stage than was seen with LPS extracts. Supplementing the experimental observations of the toxicology and immunotoxicology of cyanobacterial LPS are insights gained from beyond the cyanobacteria literature on the mechanisms of toxicity of different LPS structures. Cyanobacterial LPS was initially suggested to be toxic in the 1970s, at a time when lipid A, the active moiety of LPS, was thought to be identical across all Gram-negative bacteria. More recent work raises questions about the attribution of cutaneous and gastrointestinal illness to cyanobacterial LPS, with the understanding that some bacterial lipid A structures are LPS antagonists, LPS is not toxic by the oral route, and LPS is not reported as a toxin in the clinical dermatology literature. Gut-derived lipopolysaccharides, however, exert potent synergistic effects with a variety of xenobiotic hepatotoxins, and the well-known shock-like syndromes associated with severe cylindrospermopsin and microcystin poisoning deserve further scrutiny from the perspective of immunotoxicology.
67

Recreational Exposure To Freshwater Cyanobacteria: Epidemiology, Dermal Toxicity And Biological Activity Of Cyanobacterial Lipopolysaccharides

Stewart, Ian Unknown Date (has links)
Cyanobacteria are common inhabitants of freshwater lakes and reservoirs throughout the world. Under favourable conditions, certain cyanobacteria can dominate the phytoplankton within a waterbody and form nuisance blooms. Case reports and anecdotal references dating from 1949 describe a range of illnesses associated with recreational exposure to cyanobacteria: hay fever-like symptoms, pruritic skin rashes and gastro-intestinal symptoms (the latter probably related to ingestion of water) are most frequently reported. Some papers give convincing descriptions of allergic responses to cyanobacteria; others describe more serious acute illnesses, with symptoms such as severe headache, pneumonia, fever, myalgia, vertigo and blistering in the mouth. A U.S. coroner recently found that a teenage boy died as a result of accidentally ingesting a neurotoxic cyanotoxin from a golf course pond; this is the first recorded human fatality attributed to recreational exposure to cyanobacteria. One of the main public health concerns with exposure to freshwater cyanobacteria relates to the understanding that some blooms produce toxins that specifically affect the liver or the central nervous system. The route of exposure for these toxins is oral, from accidental or deliberate ingestion of recreational water, and possibly by inhalation. Cyanobacterial lipopolysaccharides (LPS) are also reported to be putative cutaneous, gastrointestinal, respiratory and pyrogenic toxins. The aims of this project were to enhance the understanding of public health issues relating to recreational exposure to cyanobacteria by conducting epidemiological and laboratory-based toxicology studies. A prospective cohort study of 1,331 recreational water users was conducted at various sites in southern Queensland, the Myall Lakes area of New South Wales, and central Florida. The study design sought to make improvements over previously published epidemiological studies, in that an unexposed group was recruited from cyanobacteria-free waters, cyanobacterial toxins were measured in site water samples, and respondents were asked to rate the severity of reported symptoms. This study has shown an increased likelihood of symptom reporting amongst bathers exposed to high cyanobacterial cell density (measured by total cell surface area) compared to those exposed to low cyanobacteria-affected waters. Mild respiratory symptoms appear to be the predominant symptom category. A clinical dermatology study to examine delayed-contact hypersensitivity reactions to cyanobacterial extracts was conducted. The study groups were 20 patients presenting for diagnostic skin patch testing at the Royal Brisbane Hospital's dermatology outpatient clinic; a convenience sample of 20 individuals was recruited from outside the hospital as a control group. One patient developed unequivocal reactions to several cyanobacteria extracts, with no dose-response pattern seen, indicating that the reactions were allergic in nature. A mouse model of delayed-contact hypersensitivity, the mouse ear swelling test, has demonstrated that the purified toxin cylindrospermopsin, a highly water-soluble compound, is capable of producing cutaneous injury. Encrusting lesions were seen on abdominal skin during the induction phase of these experiments. Delayed-contact hypersensitivity reactions were also demonstrated with this toxin. LPS from two non-axenic cyanobacterial samples - Cylindrospermopsis raciborskii and Microcystis aeruginosa - were extracted and purified. Thermoregulation studies were performed using a mouse model of rectal temperature measurement. Separate groups of mice were injected with these LPS extracts at two dose levels. Thermoregulation studies were also conducted with purified cyanobacterial toxins: microcystin-LR and cylindrospermopsin and anatoxin-a; cyanobacterial LPS samples purified by collaborators in Adelaide were also investigated for thermoregulation potential. These experiments have shown that the LPS extracts are weakly active when compared with responses to much lower doses of Escherichia coli LPS. Cylindrospermopsin also produces hypothermic responses in mice - comparable to pyrexia in larger mammals - although at a later stage than was seen with LPS extracts. Supplementing the experimental observations of the toxicology and immunotoxicology of cyanobacterial LPS are insights gained from beyond the cyanobacteria literature on the mechanisms of toxicity of different LPS structures. Cyanobacterial LPS was initially suggested to be toxic in the 1970s, at a time when lipid A, the active moiety of LPS, was thought to be identical across all Gram-negative bacteria. More recent work raises questions about the attribution of cutaneous and gastrointestinal illness to cyanobacterial LPS, with the understanding that some bacterial lipid A structures are LPS antagonists, LPS is not toxic by the oral route, and LPS is not reported as a toxin in the clinical dermatology literature. Gut-derived lipopolysaccharides, however, exert potent synergistic effects with a variety of xenobiotic hepatotoxins, and the well-known shock-like syndromes associated with severe cylindrospermopsin and microcystin poisoning deserve further scrutiny from the perspective of immunotoxicology.
68

Recreational Exposure To Freshwater Cyanobacteria: Epidemiology, Dermal Toxicity And Biological Activity Of Cyanobacterial Lipopolysaccharides

Stewart, Ian Unknown Date (has links)
Cyanobacteria are common inhabitants of freshwater lakes and reservoirs throughout the world. Under favourable conditions, certain cyanobacteria can dominate the phytoplankton within a waterbody and form nuisance blooms. Case reports and anecdotal references dating from 1949 describe a range of illnesses associated with recreational exposure to cyanobacteria: hay fever-like symptoms, pruritic skin rashes and gastro-intestinal symptoms (the latter probably related to ingestion of water) are most frequently reported. Some papers give convincing descriptions of allergic responses to cyanobacteria; others describe more serious acute illnesses, with symptoms such as severe headache, pneumonia, fever, myalgia, vertigo and blistering in the mouth. A U.S. coroner recently found that a teenage boy died as a result of accidentally ingesting a neurotoxic cyanotoxin from a golf course pond; this is the first recorded human fatality attributed to recreational exposure to cyanobacteria. One of the main public health concerns with exposure to freshwater cyanobacteria relates to the understanding that some blooms produce toxins that specifically affect the liver or the central nervous system. The route of exposure for these toxins is oral, from accidental or deliberate ingestion of recreational water, and possibly by inhalation. Cyanobacterial lipopolysaccharides (LPS) are also reported to be putative cutaneous, gastrointestinal, respiratory and pyrogenic toxins. The aims of this project were to enhance the understanding of public health issues relating to recreational exposure to cyanobacteria by conducting epidemiological and laboratory-based toxicology studies. A prospective cohort study of 1,331 recreational water users was conducted at various sites in southern Queensland, the Myall Lakes area of New South Wales, and central Florida. The study design sought to make improvements over previously published epidemiological studies, in that an unexposed group was recruited from cyanobacteria-free waters, cyanobacterial toxins were measured in site water samples, and respondents were asked to rate the severity of reported symptoms. This study has shown an increased likelihood of symptom reporting amongst bathers exposed to high cyanobacterial cell density (measured by total cell surface area) compared to those exposed to low cyanobacteria-affected waters. Mild respiratory symptoms appear to be the predominant symptom category. A clinical dermatology study to examine delayed-contact hypersensitivity reactions to cyanobacterial extracts was conducted. The study groups were 20 patients presenting for diagnostic skin patch testing at the Royal Brisbane Hospital's dermatology outpatient clinic; a convenience sample of 20 individuals was recruited from outside the hospital as a control group. One patient developed unequivocal reactions to several cyanobacteria extracts, with no dose-response pattern seen, indicating that the reactions were allergic in nature. A mouse model of delayed-contact hypersensitivity, the mouse ear swelling test, has demonstrated that the purified toxin cylindrospermopsin, a highly water-soluble compound, is capable of producing cutaneous injury. Encrusting lesions were seen on abdominal skin during the induction phase of these experiments. Delayed-contact hypersensitivity reactions were also demonstrated with this toxin. LPS from two non-axenic cyanobacterial samples - Cylindrospermopsis raciborskii and Microcystis aeruginosa - were extracted and purified. Thermoregulation studies were performed using a mouse model of rectal temperature measurement. Separate groups of mice were injected with these LPS extracts at two dose levels. Thermoregulation studies were also conducted with purified cyanobacterial toxins: microcystin-LR and cylindrospermopsin and anatoxin-a; cyanobacterial LPS samples purified by collaborators in Adelaide were also investigated for thermoregulation potential. These experiments have shown that the LPS extracts are weakly active when compared with responses to much lower doses of Escherichia coli LPS. Cylindrospermopsin also produces hypothermic responses in mice - comparable to pyrexia in larger mammals - although at a later stage than was seen with LPS extracts. Supplementing the experimental observations of the toxicology and immunotoxicology of cyanobacterial LPS are insights gained from beyond the cyanobacteria literature on the mechanisms of toxicity of different LPS structures. Cyanobacterial LPS was initially suggested to be toxic in the 1970s, at a time when lipid A, the active moiety of LPS, was thought to be identical across all Gram-negative bacteria. More recent work raises questions about the attribution of cutaneous and gastrointestinal illness to cyanobacterial LPS, with the understanding that some bacterial lipid A structures are LPS antagonists, LPS is not toxic by the oral route, and LPS is not reported as a toxin in the clinical dermatology literature. Gut-derived lipopolysaccharides, however, exert potent synergistic effects with a variety of xenobiotic hepatotoxins, and the well-known shock-like syndromes associated with severe cylindrospermopsin and microcystin poisoning deserve further scrutiny from the perspective of immunotoxicology.
69

Recreational Exposure To Freshwater Cyanobacteria: Epidemiology, Dermal Toxicity And Biological Activity Of Cyanobacterial Lipopolysaccharides

Stewart, Ian Unknown Date (has links)
Cyanobacteria are common inhabitants of freshwater lakes and reservoirs throughout the world. Under favourable conditions, certain cyanobacteria can dominate the phytoplankton within a waterbody and form nuisance blooms. Case reports and anecdotal references dating from 1949 describe a range of illnesses associated with recreational exposure to cyanobacteria: hay fever-like symptoms, pruritic skin rashes and gastro-intestinal symptoms (the latter probably related to ingestion of water) are most frequently reported. Some papers give convincing descriptions of allergic responses to cyanobacteria; others describe more serious acute illnesses, with symptoms such as severe headache, pneumonia, fever, myalgia, vertigo and blistering in the mouth. A U.S. coroner recently found that a teenage boy died as a result of accidentally ingesting a neurotoxic cyanotoxin from a golf course pond; this is the first recorded human fatality attributed to recreational exposure to cyanobacteria. One of the main public health concerns with exposure to freshwater cyanobacteria relates to the understanding that some blooms produce toxins that specifically affect the liver or the central nervous system. The route of exposure for these toxins is oral, from accidental or deliberate ingestion of recreational water, and possibly by inhalation. Cyanobacterial lipopolysaccharides (LPS) are also reported to be putative cutaneous, gastrointestinal, respiratory and pyrogenic toxins. The aims of this project were to enhance the understanding of public health issues relating to recreational exposure to cyanobacteria by conducting epidemiological and laboratory-based toxicology studies. A prospective cohort study of 1,331 recreational water users was conducted at various sites in southern Queensland, the Myall Lakes area of New South Wales, and central Florida. The study design sought to make improvements over previously published epidemiological studies, in that an unexposed group was recruited from cyanobacteria-free waters, cyanobacterial toxins were measured in site water samples, and respondents were asked to rate the severity of reported symptoms. This study has shown an increased likelihood of symptom reporting amongst bathers exposed to high cyanobacterial cell density (measured by total cell surface area) compared to those exposed to low cyanobacteria-affected waters. Mild respiratory symptoms appear to be the predominant symptom category. A clinical dermatology study to examine delayed-contact hypersensitivity reactions to cyanobacterial extracts was conducted. The study groups were 20 patients presenting for diagnostic skin patch testing at the Royal Brisbane Hospital's dermatology outpatient clinic; a convenience sample of 20 individuals was recruited from outside the hospital as a control group. One patient developed unequivocal reactions to several cyanobacteria extracts, with no dose-response pattern seen, indicating that the reactions were allergic in nature. A mouse model of delayed-contact hypersensitivity, the mouse ear swelling test, has demonstrated that the purified toxin cylindrospermopsin, a highly water-soluble compound, is capable of producing cutaneous injury. Encrusting lesions were seen on abdominal skin during the induction phase of these experiments. Delayed-contact hypersensitivity reactions were also demonstrated with this toxin. LPS from two non-axenic cyanobacterial samples - Cylindrospermopsis raciborskii and Microcystis aeruginosa - were extracted and purified. Thermoregulation studies were performed using a mouse model of rectal temperature measurement. Separate groups of mice were injected with these LPS extracts at two dose levels. Thermoregulation studies were also conducted with purified cyanobacterial toxins: microcystin-LR and cylindrospermopsin and anatoxin-a; cyanobacterial LPS samples purified by collaborators in Adelaide were also investigated for thermoregulation potential. These experiments have shown that the LPS extracts are weakly active when compared with responses to much lower doses of Escherichia coli LPS. Cylindrospermopsin also produces hypothermic responses in mice - comparable to pyrexia in larger mammals - although at a later stage than was seen with LPS extracts. Supplementing the experimental observations of the toxicology and immunotoxicology of cyanobacterial LPS are insights gained from beyond the cyanobacteria literature on the mechanisms of toxicity of different LPS structures. Cyanobacterial LPS was initially suggested to be toxic in the 1970s, at a time when lipid A, the active moiety of LPS, was thought to be identical across all Gram-negative bacteria. More recent work raises questions about the attribution of cutaneous and gastrointestinal illness to cyanobacterial LPS, with the understanding that some bacterial lipid A structures are LPS antagonists, LPS is not toxic by the oral route, and LPS is not reported as a toxin in the clinical dermatology literature. Gut-derived lipopolysaccharides, however, exert potent synergistic effects with a variety of xenobiotic hepatotoxins, and the well-known shock-like syndromes associated with severe cylindrospermopsin and microcystin poisoning deserve further scrutiny from the perspective of immunotoxicology.
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Respiratory health effects of occupational exposure to bushfire smoke in Western Australia

De Vos, Johanna B. M. January 2008 (has links)
Bushfires are an integral part of the Australian environment, and consequently Australian fire fighters are regularly confronted with the challenge of bushfire fighting activities. Bushfires can be extensive and long-lasting, and as a result fire fighters can be exposed to bushfire smoke for long periods without respite. Anecdotal evidence suggests that bushfire smoke exposure can lead to respiratory symptoms such as coughing, wheezing, and shortness of breath. In an optimal environment, fire fighters are equipped with respirators and protective filters to prevent the inhalation of the air toxics in bushfire smoke. Yet, reports from the fire ground indicate that the protective filters are not effective in preventing the inhalation of bushfire smoke. As a result, fire fighters have increasingly expressed concern about the ineffective equipment and the resultant respiratory symptoms during and after bushfire fighting. This research aims to establish a scientific data base to support the anecdotal evidence. The objectives of the research were: (1) to identify and quantify the air toxics in Western Australian bushfire smoke; (2) to profile the acute respiratory health effects associated with bushfire smoke exposure; (3) to assess the effectiveness of three different types of filters under controlled conditions in a smoke chamber, and in the field during fuel reduction burn-off; (4) to formulate recommendations for reducing fire fighters' exposure to bushfire smoke; and (5) to inform policy decision makers about the most effective form of respiratory protective equipment for bushfire fighting. Exposure trials were conducted in an experimental setting utilising bushfire smoke conditions in a smoke chamber and during prescribed burn-offs. Repeated measurements of respiratory symptoms, pulmonary function and oximetry were undertaken before and after bushfire smoke exposure. In addition, personal air sampling inside the respirators was undertaken to quantify and compare the levels of filtered air toxics. The analysis of the collected data demonstrated that, of those compared, the particulate/organic vapour formaldehyde filter was most effective in protecting fire fighters' respiratory health during the smoke exposure period of maximally 120 minutes. Further research would be useful to determine the v effectiveness of the filters under more realistic conditions during bushfire fighting activities. The findings of this research have resulted in a policy review in Western Australia. In 2006, the Fire and Emergency Services Authority of Western Australia (FESA) reviewed its Bush Fire Smoke Exposure Standard Operational Procedures 51, and now issues the recommended particulate/organic vapour/formaldehyde filters to the 1,000 FESA career fire fighters. The use of protective equipment for bushfire fighters is inadequately regulated worldwide and the recommendation implemented by FESA can be seen as proactive and in advance of national and international best practice. In conclusion, this project was instrumental in the translation of public health research into best practice that protects occupational health, without the need for the lengthy process of legislative reform. Fire fighter organisations in other countries with high frequencies of bushfires could learn from this example, and move to review their policies and introduce adequate personal protection for fire fighters.

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