Mortality and workers' compensation patterns were studied among 1,064 Ontario asbestos insulation workers. A proportional mortality analysis of 153 asbestos worker deaths found increased mortality from malignant diseases (65 deaths observed; 35.1 expected), cancers of the lungs and pleura (32 deaths observed; 11.5 expected), peritoneal mesothelioma (4 deaths), and respiratory diseases (14 deaths observed; 7.9 expected). Despite the publicity given to asbestos-associated diseases, dependents of many men potentially eligible for workers compensation awards have not received pensions because claims were not filed. These findings suggest that much occupationally related disease is not being recognized in Ontario.
Universal health care systems seek to ensure access to care on the basis of need, rather than income, but there are concerns about preferential access to cardiovascular and specialist care for high income patients. In this study, I used population-based, individual-level health, income and utilization data to determine whether whether there is evidence for differential access to physician care in relation to household income.
I studied data for 2170 Ontario respondents to the 1995 National Population Health Survey (aged 40 to 79 years) who had approved linkage of their survey responses to the administrative databases of the Ontario Health Insurance Plan and for whom income data were available. I used linear and generalized linear regression to model the mean per capita expenditures on physician care and the probability of referral to a specialist in relation to income and self-reported health status.
Residents of higher income households incurred lower per capita expenditures for physicians' services than those in lower income households; for example, the mean per capita expenditure in the upper middle income group was $220 less (95% confidence interval -$87 to -$334) than the mean per capita expenditure in the lowest income group. Expenditures were significantly related to self-reported health status; for example, the mean per capita expenditure among those reporting fair health status was $590 higher (95% confidence interval $465 to $737) than among those reporting excellent health. After adjustment for health status, there was no association between income and the expenditures on all physician services, out-of-hospital services or specialist care.
Utilization of physicians' services in Ontario is based on need, rather than income.
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Mortality among 535 asbestos-exposed and 205 nonexposed employees of an asbestos-cement factory was investigated. In the period beyond 20 yr from first exposure, the exposed workers had standardized mortality ratios of 175 for all causes of death, 370 for all malignancies, 480 for lung cancer, 240 for gastrointestinal cancers, and 17 deaths from mesothelioma; the factory control subjects had mortality rates similar to the general population. The cell-type distribution of the lung cancers was similar to that occurring in middle-aged smokers. Cumulative fiber exposures were calculated for the production workers, and mortality rates for the asbestos-associated malignancies were found to have significant trends with exposure. Exposure-related lung cancer risks were noted, with a large margin of uncertainty, to be similar to those observed in an American study of manmade mineral fiber workers.
The mortality of workers from an Ontario factory manufacturing amosite asbestos insulation materials under poorly controlled environmental conditions is reported here. Seven (58%) of 12 deaths among exposed workers 10 or more years after first exposure were due to malignancies; four (25%) were from lung cancer, and there were two deaths from peritoneal mesothelioma. Those dying from mesothelioma were 47 and 49 years of age. Three (25%) of 12 deaths were from respiratory disease, two were attributed to asbestosis (in men 42 and 53 years of ages), and one to pneumonia in a 54-year-old male.
This paper describes mortality in a cohort of 324 men exposed to chrysotile asbestos and coal tar pitch used in the manufacture of electrical conduit pipe from a mixture of newsprint, bentonite, and asbestos. One death in a factory worker was attributed to pleural mesothelioma, and long-term employees experienced an increased risk of lung cancer (Standardized Mortality Ratio (SMR) 221; six deaths) and non-malignant respiratory disease (SMR 215; four deaths). In a case-control analysis, men whose jobs involved adding asbestos to the mix of raw materials were found to have a risk of lung cancer sevenfold higher (lower 95% confidence limit: 2.3) than men who had never worked at this job. Exposure to coal tar pitch is presumed to be responsible for the death of one worker from squamous cell carcinoma of the scrotum.
Mortality was studied among a group of 328 employees of an Ontario asbestos-cement factory who had been hired before 1960 and who had been employed for a minimum of nine years. The group of 87 men who had worked in the rock wool/fibre glass operations, or who had been otherwise minimally exposed to asbestos, had mortality rates similar to those of the general Ontario population, while the group of asbestos-exposed employees had all-cause mortality rates double those of the Ontario population, mortality rates due to malignancies five times higher than expected, and deaths attributed to lung cancer eight times more frequent than expected. According to the best evidence available, 10 of 58 deaths among the production workers were due to malignant mesothelioma and 20 to lung cancer. The men dying of mesothelioma were younger than the men dying of lung cancer with mean ages at death of 51 and 64 years respectively. An exposure model was constructed on the basis of the available air sampling data, and individual exposure histories were calculated. These exposure histories were used to investigate the exposure-response relationships for asbestos-associated malignancies.
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A study of the mortality rates among 1657 employees at two Ontario automotive parts factories that manufactured friction materials containing chrysotile asbestos was initiated in response to the workers' concerns about the effects of asbestos on their health. A total of 1194 men and 258 women had had their first potential exposure at least 10 years before the end of the study period; 563 of the men and 138 of the women had had such an exposure at least 20 years before the end of the study period. A significantly increased rate of death from laryngeal cancer and an elevated rate of death from lung cancer were observed in a cohort analysis. One or two deaths might have been due to pleural mesothelioma. There was no increase in the rate of death from gastrointestinal cancer or from nonmalignant respiratory disease. Case-control analysis showed no association between the risk of laryngeal or lung cancer and the total duration of employment (a surrogate for the extent of ambient exposure to asbestos or other workplace toxic substances) or employment in departments where asbestos had been used. An association between risk of death and occupational exposure is uncertain.
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A death certificate case-control study of sinonasal cancer in Ontario has found increased relative risks among wood-workers. The results from four North American studies have been combined using the Mantel-Haenszel method, and the relative risk for woodworkers has been found to be 1.6 (P less than .01). It is concluded that North American softwoods, as well as hardwoods, may contain carcinogenic substances or their precursors.