A retrospective cohort study was undertaken to investigate the cancer mortality of granite workers. The study comprised 1,026 workers hired between 1940 and 1971. The number of person-years was 20,165, and the number of deaths 235. During the total follow-up 46 tumors were observed and 44.9 were expected. An excess mortality from tumors was observed for the workers followed for 20 years or more, the greatest excess occurring during the follow-up period of 25-29 years (observed 11, expected 5.2). Of the 46 tumors, 22 were lung cancers (expected 17.1) and 15 were gastrointestinal cancers (expected 9.7), nine of which were cancers of the stomach (expected 6.0). Mortality from lung cancer was excessive for workers with at least 15 years since entry into granite work (latency) (21 observed and 9.5 expected), being highest during the follow-up period of 25-29 years (observed 8, expected 2.1). The results indicate that granite exposure per se may be an etiologic factor in the initiation or promotion of malignant neoplasms.
The authors examined the components and modifiers of the healthy worker effect using mortality data from three occupational cohorts: the employees of Atomic Energy of Canada Limited followed between 1950 and 1981, a 10% sample of the Canadian labor force followed between 1965 and 1979, and workers at the Eldorado Resources Limited Beaverlodge uranium mine followed between 1950 and 1980. Two important components of the healthy worker effect have been identified in these cohorts, namely, initial selection of and continuing employment of healthy individuals. There is less evidence for a contribution from the existence of differential risk factors among employed individuals as compared with the general population. The healthy worker effect is, however, substantially modified by time since employment, sex, age, specific cause of death, and specific occupation. Because of this variation, it is inappropriate to account for the healthy worker effect by a single parameter, and all of the above factors must be taken into account in any appropriate analysis. When the only available comparison group for an occupational cohort is the general population, the healthy worker effect is unlikely to have any substantial influence on the process of assessing causality for any observed association or attributing cause in an individual case. This would be particularly true for cancer, and even more so for lung cancer, a disease often associated with industrial compensation cases.
The article is devoted to coronary disease in miners of deep Donbass mines. Data of its prevalence, chemical and functional features are given. Rapid progress of the disease was found to correlate with unfavourable factors of occupational environment. Mechanisms of dangerous heart rythm disorders formation during the work are shown. The main points of the programme improving the health care of miners suffering from coronary heart disease are described.
The authors studied autopsy protocols, microscopic and histochemical data on the heart for miners who had died suddenly. No positive trend in the sudden coronary death incidence in miners was reported. A great number of sudden deaths were registered in mines. The deaths are attributed to severe atherosclerosis responsible for irreversible changes in the myocardium, coronary vascular spasms, emergence of pathological agitation triggering lethal ischemia.
A cohort study of 8,487 workers employed between 1948 and 1980 at a uranium mine in Saskatchewan, Canada, has been conducted. A total of 65 lung cancer deaths was observed (34.24 expected, P less than 10(-5)). There was a highly significant linear relationship between dose and increased risk of lung cancer giving estimates for the relative and attributable risk coefficients of 3.28% per working level month (WLM) and 20.8 per WLM per 10(6) person-years. Age at first exposure had a significant modifying effect on risk. The interaction of exposure with age at observation fits a relative risk model well. The similarity of these results to a recent study of Swedish iron miners with similar levels of relatively low exposure suggests that exposure to radon daughter products may be a major contributory factor to lung cancer occurring among nonsmokers in the general population. The results also reinforce concerns as to the appropriateness of present occupational exposure standards.
A cohort study of 2,103 workers employed between 1942 and 1960 at a uranium mine in the Northwest Territories, Canada, was conducted. A total of 57 lung cancer deaths was observed (expected = 24.73, P less than .0001). There was a highly significant linear relationship between exposure and increased risk of lung cancer, giving estimates for the relative and attributable risk coefficients of 0.27 per working level month (WLM) and 3.10 per WLM per 10(6) person-years. These risk coefficients were substantially less than those estimated from the experience of miners in the Beaverlodge mine, which have previously been reported. Any biases in the present estimates are likely to have been upward, and therefore they probably represent an upper limit. The major difference between the two mine cohorts is in the exposure rate, since the Port Radium miners were exposed to much greater concentrations of radon daughters than the Beaverlodge miners. It is postulated that risk of lung cancer from radon daughter exposure may be modified by exposure rate, for which hypothesis there is some support from other epidemiologic data.
The objective of the present study was to investigate the mortality, disability, and long-term morbidity of granite workers. The study included 1,026 workers hired between 1940 and 1971 and followed until the end of 1981. The total number of deaths was 235, and the expected number was 229.7. Excess mortality rates were observed for respiratory diseases (observed/expected = 28/13.9). The number of tumor deaths was 46 (expected 44.9). Excess lung cancer mortality was evident at 15 to 35 years of latency; the observed number of lung cancer deaths for the follow-up period of 25 to 29 years was 8, while 2.1 were expected. Mortality from cardiovascular diseases and violent deaths was slightly less than expected. The results for disability and long-term morbidity showed elevated incidence and prevalence rates for respiratory diseases and rheumatoid arthritis. The observed number of disability pensions due to rheumatoid arthritis in 1981 was 10 observed versus 1.8 expected, and the observed number of patients granted free medication was 19 versus 8.1 expected. The results indicate that granite dust exposure per se may be an etiologic and pathogenetic factor for lung cancer, cancer of the gastrointestinal tract, and some extrapulmonary nonmalignant chronic diseases.
An epidemiological follow-up study of 16,000 uranium mine and refinery employees has made use of computerized techniques for searching a national death file. The accuracy of this computerized matching has been compared with that of corresponding manual searches based on one-eighth of the worker file. The national death file--Canadian Mortality Data Base--at Statistics Canada includes coded causes of death for all deaths back to 1950. The machine search was carried out using a generalized record linkage system based upon a probabilistic approach. The machine was more successful than the manual searchers and was also less likely to yield false linkages with death records not related to the study population. In both approaches accuracy was strongly dependent on the amount of personal identifying information available on the records being linked.
Work related dust exposure is a risk factor for acute and chronic respiratory irritation and inflammation. Exposure to dust and cigarette smoke predisposes to exogenous viral and bacterial infections of the respiratory tract. Respiratory infection can also act as a risk factor in the development of atherosclerotic and coronary artery disease.
To investigate the association of dust exposure and respiratory diseases with ischaemic heart disease (IHD) and other cardiovascular diseases (CVDs).
The study comprised 6022 dust exposed (granite, foundry, cotton mill, iron foundry, metal product, and electrical) workers hired in 1940-76 and followed until the end of 1992. National mortality and morbidity registers and questionnaires were used. The statistical methods were person-year analysis and Cox regression.
Co-morbidity from cardiovascular and respiratory diseases ranged from 17% to 35%. In at least 60% of the co-morbidity cases a respiratory disease preceded a cardiovascular disease. Chronic bronchitis, pneumonia, and upper respiratory track infections predicted IHD in granite workers (rate ratio (RR) = 1.9; 95% CI 1.38 to 2.72), foundry workers (2.1; 1.48 to 2.93), and iron foundry workers (1.7; 1.16 to 2.35). Dust exposure was not a significant predictor of IHD or other CVD in any group. Dust exposure was related to respiratory morbidity. Thus, some respiratory diseases appeared to act as intermediate variables in the association of dust exposure with IHD.
Dust exposure had only a small direct effect on IHD and other CVD. IHD morbidity was associated with preceding respiratory morbidity. A chronic infectious respiratory tract disease appeared to play an independent role in the development of IHD.
Cites: Circulation. 1998 Feb 24;97(7):633-69495296