A cohort of some 11,000 men born 1891-1920 and employed for at least one month in the chrysotile mines and mills of Quebec, was established in 1966 and has been followed ever since. Of the 5351 men surviving into 1976, only 16 could not be traced; 2508 were still alive in 1989, and 2827 had died; by the end of 1992 a further 698 were known to have died, giving an overall mortality of almost 80%. This paper presents the results of analysis of mortality for the period 1976 to 1988 inclusive, obtained by the subject-years method, with Quebec mortality for reference. In many respects the standardised mortality ratios (SMRs) 20 years or more after first employment were similar to those for the period 1951-75--namely, all causes 1.07 (1951-75, 1.09); heart disease 1.02 (1.04); cerebrovascular disease 1.06 (1.07); external causes 1.17 (1.17). The SMR for lung cancer, however, rose from 1.25 to 1.39 and deaths from mesothelioma increased from eight (10 before review) to 25; deaths from respiratory tuberculosis fell from 57 to five. Among men whose exposure by age 55 was at least 300 million particles per cubic foot x years (mpcf.y), the SMR (all causes) was elevated in the two main mining regions, Asbestos and Thetford Mines, and for the small factory in Asbestos; so were the SMRs for lung cancer, ischaemic heart disease, cerebrovascular disease, and respiratory disease other than pneumoconiosis. Except for lung cancer, however, there was little convincing evidence of gradients over four classes of exposure, divided at 30, 100, and 300 mpcf.y. Over seven narrower categories of exposure up to 300 mpcf.y the SMR for lung cancer fluctuated around 1.27 with no indication of trend, but increased steeply above that level. Mortality form pneumoconiosis was strongly related to exposure, and the trend for mesothelioma was not dissimilar. Mortality generally was related systematically to cigarette smoking habit, recorded in life from 99% of survivors into 1976; smokers of 20 or more cigarettes a day had the highest SMRs not only for lung cancer but also for all causes, cancer of the stomach, pancreas, and larynx, and ischaemic heart disease. For lung cancer SMRs increased fivefold with smoking, but the increase with dust exposure was comparatively slight for non-smokers, lower again for ex-smokers, and negligible for smokers of at least 20 cigarettes a day; thus the asbestos-smoking interaction was less than multiplicative. Of the 33 deaths from mesothelioma in the cohort to date, 28 were in miners and millers and five were in employees of a small asbestos products factory where commercial amphiboles had also been used. Preliminary analysis also suggest that the risk of mesothelioma was higher in the mines and mills at Thetford Mines than in those at Asbestos. More detailed studies of these differences and of exposure-response relations for lung cancer are under way.
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The article contains results concerning spectral analysis of biologic materials (blood and hair) for heavy metals content. These results helped to reveal health risk factors for workers engaged into chromium ores extraction and for nearby residents.
Health administrative data can be a valuable tool for disease surveillance and research. Few studies have rigorously evaluated the accuracy of administrative databases for identifying rheumatoid arthritis (RA) patients. Our aim was to validate administrative data algorithms to identify RA patients in Ontario, Canada.
We performed a retrospective review of a random sample of 450 patients from 18 rheumatology clinics. Using rheumatologist-reported diagnosis as the reference standard, we tested and validated different combinations of physician billing, hospitalization, and pharmacy data.
One hundred forty-nine rheumatology patients were classified as having RA and 301 were classified as not having RA based on our reference standard definition (study RA prevalence 33%). Overall, algorithms that included physician billings had excellent sensitivity (range 94-100%). Specificity and positive predictive value (PPV) were modest to excellent and increased when algorithms included multiple physician claims or specialist claims. The addition of RA medications did not significantly improve algorithm performance. The algorithm of "(1 hospitalization RA code ever) OR (3 physician RA diagnosis codes [claims] with =1 by a specialist in a 2-year period)" had a sensitivity of 97%, specificity of 85%, PPV of 76%, and negative predictive value of 98%. Most RA patients (84%) had an RA diagnosis code present in the administrative data within ±1 year of a rheumatologist's documented diagnosis date.
We demonstrated that administrative data can be used to identify RA patients with a high degree of accuracy. RA diagnosis date and disease duration are fairly well estimated from administrative data in jurisdictions of universal health care insurance.
An expert evaluation of identifiability of cardiovascular diseases was carried out together with a clinical and functional examination of certain groups of miners of basic underground occupations at different ages and lengths of service, that showed a high incidence of cardiovascular diseases along with a low informative value of methodical approaches, indices and criteria used for their diagnosis in conducting preliminary and periodic health check-ups. To improve the quality of diagnosis of diseases of the circulatory system it is necessary that standardized methods of investigation should be employed together with consistent indices of high informative value as well as a purposive training of physicians.
The research purpose is an estimation of influence of the bauxite dust on the state of the bronchopulmonary system of workers. It has been indicated that exposure of the poor fibrogenic dust while the process of the bauxite ore extraction, results in development of pnevmokoniosis characterized by substantial ventilatory and haemodynamic disorders limiting the workability of patients.
The analysis of age features of prevalence of an arterial hypertensia in the basic professional groups of the coal-mining enterprises was carried out. In total 1575 workers of collieries and cuts of Kuzbas united in 9 professional groups participated in the research. The results of research demonstrated the distinctions of age structure in the professional groups, testifying about expressed professional senescence among workers of mines, which reveals itself in the decrease in relative density of persons of 50+ years. In these groups with the expressed professional senescence the decrease in relative density of persons with an arterial hypertensia--so-called effect of the "healthy worker", in turn, is observed.
The study investigated whether occupational accident risks were equally distributed across age categories over time in the context of production reorganization and work rationalization in a Swedish iron ore mine between 1980 and 1993. Three phases of reorganization, defined by productivity levels, and four age categories were related to age-related accident risk ratios using the Poisson-regression method. Accident risk ratios (ARRs) were found systematically to be higher during the two first phases and also for younger workers, in the cases of both nonspecific and specific accident risks. The steady reduction in accident rates observed did not favor all age groups of workers to the same extent. For two accident patterns out of five, workers in their thirties and forties recorded higher ARRs than those in their fifties.
The paper examines age-related accident risks faced by Swedish male iron-ore miners. A retrospective longitudinal analysis of national registers was conducted over a ten-year period using three times periods of five years and five age categories. Age-related accident frequency, characteristics and severity were examined. High accident ratios were rare among older miners whatever the time period, but some accident patterns became substantially more frequent in some older age cohorts over the years. Injuries tended to be more severe in older age groups, all accidents aggregated as well as by accident pattern. It is concluded that inequality in risk exposure between age groups may explain the lower accident ratios found among older workers, but also that the aging of a working population may lead to the application of task-assignment principles that penalize older workers, at least with regard to certain specific accident risks.