http://hdl.handle.net/1956/941 Search the Channel search http://bora.uib.no/simple-search http://hdl.handle.net/1956/2321 Title: Retrospective assessment of exposure to carcinogens in Norway’s offshore petroleum industry <br/> <br/>Authors: Steinsvåg, Kjersti <br/> <br/>Abstract: Objectives: The main research objective of the four articles comprising this dissertation was to provide retrospective exposure information for a planned study on cancer in a cohort within Norway’s offshore petroleum industry. Methods: Background information on possible exposure was obtained through company visits, including interviewing key personnel (n = 83) and collecting monitoring reports (n = 118) and other relevant documents (n = 329). The collected material was used to identify relevant carcinogens. Twenty-seven job categories were defined based on a previous questionnaire administered to present and former offshore employees in 1998. Descriptions of products containing known and suspected carcinogens, exposure sources and processes were extracted from the collected documentation and the interviews of key personnel (Article II). Exposure data on oil mist and oil vapour covered 37 drilling facilities and were analysed by descriptive statistics and by constructing linear mixed-effects models (Article I). A group of three university and five industry experts individually assessed the likelihood (unlikely, possible or probable) of exposure for combinations of 17 carcinogens, 27 job categories and four time periods (1970–1979, 1980–1989, 1990–1999 and 2000–2005). Each rater was to assess 1836 combinations based on summary documents on carcinogenic agents, which included descriptions of sources of exposure and products, descriptions of work processes carried out within the different job categories and monitoring data. Interrater agreement was calculated using Cohen’s kappa index and single and average score intraclass correlation coefficients. Differences in interrater agreement between the different time periods, raters, carcinogen class and amount of information provided were then studied (Article III). In subsequent plenary discussions, the experts agreed on exposed combinations. Agreement between the individual and the panel assessments was calculated using Cohen’s kappa index. Using the panel assessment as reference, sensitivity and specificity were estimated (Article IV). Results: This study indicated possible exposure to the following known and suspected carcinogenic agents, mixtures or exposure circumstances: benzene; mineral oil – inhalation exposure; mineral oil – skin exposure; crystalline silica; asbestos; refractory ceramic fibres; formaldehyde; tetrachloroethylene; trichloroethylene; welding; nickel compounds; chromium [VI]; lead; crude oil – skin exposure; diesel engine exhaust; dichloromethane; ionising radiation; and occupational exposure as a painter (Article II). Monitoring reports were obtained on seven agents: benzene, mineral oil mist and vapour, respirable and total dust, asbestos fibres, refractory ceramic fibres, formaldehyde and tetrachloroethylene (Article II). The arithmetic mean of 367 personal samples of benzene was 0.037 ppm (range: less than the limit of detection – 2.6 ppm). Asbestos fibres were detected (0.03 fibres/cm3) when asbestos-containing brake bands were used in drilling draw work in 1988. The personal exposure to formaldehyde in the process area ranged from 0.06 to 0.29 mg/m3. Samples of oil mist and oil vapour had been taken during the use of three generations of hydrocarbon base oils: diesel oils (1979–1984), low-aromatic mineral oils (1985–1997) and nonaromatic mineral oils (1998–2004). Sampling done before 1984 showed high exposure to diesel vapour (arithmetic mean = 1217 mg/m3). Downward time trends were indicated for both oil mist (6% per year) and oil vapour (8% per year) when the year of monitoring was introduced as a fixed effect in a linear mixed-effects model analysis. Rig type, technical control measures and mud temperature significantly determined exposure to oil mist. Rig type, type of base oil, viscosity of the base oil, work area, mud temperature and season significantly determined exposure to oil vapour. In these models major decreases in variability were found for the between-rig components (Article I). In the individual expert assessment overall, 336 (18%) of the 1836 combinations were denoted possible exposure, and 253 (14%) scored probable exposure. Stratified on the 17 carcinogenic agents, the prevalence of probable exposure ranged from 3.8% for refractory ceramic fibres to 30% for crude oil. The overall mean kappa (κ) was 0.42; single score intraclass correlation coefficient was 0.62, and the average intraclass correlation coefficient was 0.93. Providing limited quantitative measurement data was associated with less agreement than for equally well-described carcinogens without sampling data. The eight experts assessed 1157 (63%) of the 1836 combinations in plenary, resulting in 265 (14%) agreed exposed combinations. The agreement between the experts’ individual assessments and the panel assessment was κ = 0.53–0.74. The sensitivity was 0.55–0.86 and specificity 0.91–0.97. For these parameters, there were no apparent differences between the university experts and the industry experts. Conclusions For defined job categories in Norway’s offshore petroleum industry this study describes possible exposure to known and suspected carcinogenic agents, mixtures or exposure circumstances. An expert panel agreed on probable exposure for 265 of 1836 possible combinations of 17 agents, 27 job categories and four time periods. Measurement data on seven agents are presented. Benzene and mineral oil mist and vapour were considered to have the best potential for development of quantitative estimates of exposure. Exposure to oil mist and oil vapour declined over time in the mud-handling areas of offshore drilling facilities. Exposure was associated with rig type, mud temperature, technical control measures, base oil, viscosity of the base oil, work area and season. The eight raters in the expert group seemed to have enough documentation on which to base their individual estimates. However, providing limited monitoring data leads to more incongruence among raters. The group was large enough to give reliable estimates. The experts’ individual ratings highly agreed with the succeeding panel assessment. The university experts and the industry experts’ assessments did not apparently differ. Thu, 14 Jun 2007 22:58:59 GMT http://hdl.handle.net/1956/2209 Title: High prevalence of respiratory symptoms among workers in the development section of a manually operated coal mine in a developing country : a cross sectional study <br/> <br/>Authors: Mamuya, Simon H. D.; Bråtveit, Magne; Mashalla, Yohana; Moen, Bente E. <br/> <br/>Abstract: Background: Few studies of miners have been carried out in African countries; most are from South Africa, where the working conditions are assumed to be better than in the rest of Africa. Several studies have focused on respiratory disorders among miners, but development workers responsible for creating underground road ways have not been studied explicitly. This is the first study assessing the associations between exposure to dust and quartz and respiratory symptoms among coal mine workers in a manually operated coal mine in Tanzania, focusing on development workers, as they have the highest exposure to coal dust. Methods: A cross-sectional study was carried out among 250 production workers from a coal mine. Interviews were performed using modified standardized questionnaires to elicit information on occupational history, demographics, smoking habits and acute and chronic respiratory symptoms. The relationships between current dust exposure as well as cumulative respirable dust and quartz and symptoms were studied by group comparisons as well as logistic regression. Results: Workers from the development group had the highest dust exposure, with arithmetic mean of 10.3 mg/m3 for current respirable dust and 1.268 mg/m3 for quartz. Analogous exposure results for mine workers were 0.66 mg/m3 and 0.03 mg/m3, respectively; and for other development workers were 0.88 mg/m3 and 0.10 mg/m3, respectively. The workers from the development section had significantly higher prevalence of the acute symptoms of dry cough (45.7%), breathlessness (34.8%) and blocked nose (23.9%). In addition, development workers had significantly more chronic symptoms of breathlessness (17.0%) than the mine workers (6.4%) and the other production workers (2.4%). The highest decile of cumulative exposure to respirable dust was significantly associated with cough (OR = 2.91, 95% CI 1.06, 7.97) as were cumulative exposure to quartz and cough (OR = 2.87, CI 1.05, 7.88), compared with the reference consisting of the group of workers with the lowest quartile of the respective cumulative exposure. Conclusion: The development workers in a coal mine had more acute and chronic respiratory symptoms than the mine and the other production workers. In addition, there was an association between high cumulative coal dust and respiratory symptoms. Wed, 31 Jan 2007 22:58:59 GMT http://hdl.handle.net/1956/2203 Title: Epidemiological studies of multiple sclerosis in a Sardinian population, insular Italy : cluster studies and health status <br/> <br/>Authors: Pugliatti, Maura <br/> <br/>Abstract: MS is a disorder of the central nervous system, manifesting as acute focal inflammatory demyelination and axonal loss, and culminating with chronic multifocal sclerotic plaques. MS involves several nervous functional systems resulting in disability, has a rather unpredictable course, and thus leads to poorer quality of life. It is a disorder of young adults, and the most common cause of non post-traumatic neurological disability. It is believed to be caused by interplay between genes and the environment. Potentially any environmental agent can have a role in determining MS in susceptible populations and yet be neither a necessary nor a sufficient cause. Potential risk factors have been investigated, such as infectious agents, vaccines, stress, occupation, climate and nutrition. At what age in a genetically predisposed individual’s life, exogenous factors can interact to initiate MS is rather controversial, although this probably occurs within the first 15 years of life. The present work involves two broad areas in MS research: (i) epidemiological descriptive studies aimed at disclosing clues to disease etiology and mechanisms of disease induction, and (ii) the study of determinants of health-related quality of life in the MS population at large. The specific objectives to this work were: to disclose MS variation at a microgeographic level, as a possible expression of the spatial distribution of disease risk factor(s) (Paper I); to update and characterise MS incidence patterns, as a possible expression of temporal distribution of disease risk factor(s) (Paper II); to assess whether individuals that later develop MS have shared the same environment at the same age indicating common exposure to disease factor(s), and if so at what age has this occurred (Paper III); and to compare the self-perceived health status to the general population, with special regards to physical functioning, in MS patients with no or mild disability as objectively measured (Paper IV). All these studies have been conducted on the province of Sassari, northern Sardinia, insular Italy (450,000 pop. circa) based on a registry system of MS cases. Epidemiological studies conducted over the past two decades using repeated assessments have shown that Sardinia is at high risk for MS with a prevalence of 150 per 100,000 and an annual mean incidence of 6 per 100,000. To investigate the distribution of MS in Sardinia at microgeographic level a spatial analysis of the disease prevalence in the study area for year 1997 was conducted (Paper I). To overcome random variability due to small numbers of cases per geographic unit, a hierarchical Bayesian approach was adopted. Spatial clustering patterns in the province south-west and a west-to-east gradient were observed. An incidence study was performed on 689 MS patients with disease onset between 1965 and 1999 in the study area (Paper II). The mean annual incidence rate increased significantly from 1 per 100,000 pop in 1965–69 to 6 in 1995–99, with no differences for gender and province sub-areas. The mean age at onset increased significantly during the same period from 25.7 to 30.6 years, while the proportion of patients with progressive initial course declined over time. Space-time cluster analysis was performed in the study area to indicate a possible shared exposure to MS risk(s) factors during the disease latent period, and the individuals’ age for this susceptibility period (Paper III). Residence changes from birth to clinical onset were recorded for all MS patients with clinical onset between 1965 and 1999 in the study area. Closeness in space and time was defined as living in the same commune, at the same time and at the same age differing only by 1, 2 or 5 years. The analysis was performed from birth until age 25 years or disease clinical onset, and by demographic and clinical subgroups. Clustering was substantial in early childhood. It was most marked in the most recent cases, among women and in patients with relapsing-remitting course. No clustering was found when closeness in time was defined as a fixed number of years before onset, arguing against a fixed latency period of the disease. MS heterogeneous spatial distribution at microgeographic level, its increased incidence and change of clinico-demographic phenotypes over a relatively short period of time, and evidences of clustering in space and time in early childhood especially occurring recently, are suggestive for the action of an exogenous factor(s) in determining MS. Ecological and case-control studies need to be designed and implemented to validate and characterise these observations. The self-perceived health status among MS patients with no or mild disability according to EDSS and the impact of self-rated physical functioning have been compared between a sample of fully ambulatory (EDSS ≤3.5) MS patients and the general population (Paper IV). SF-36 was used to self-rate health status. The 197 MS patients analysed (150 women and 47 men) had significantly lower mean SF-36 scores than the general population, except for bodily pain. Similar results were found for a sub sample of 107 patients (81 women and 26 men) with even lower disability (EDSS ≤2.0). EDSS correlated weakly with the physical functioning subscale, explaining only 2% of the variance in such SF-36 subscale. The regression of the physical functioning subscale on the other seven SF-36 subscales was significantly lower among MS patients than in the general population for all subscales, except for role limitation due to physical health problems and social functioning. Therefore factors other than physical functioning contribute to the low scores for the other dimensions compared with the general population. Neither disease course nor duration correlated significantly with SF-36 subscales. Strategies targeting a broad spectrum of health related issues for MS patients should be implemented starting already in the disease early stage. For cost-of-illness studies these findings provide clues to indicators to the disease socio-economic burden in the early stages, and elements for disease-specific interventions. Thu, 29 Mar 2007 22:58:59 GMT