Annual visits to GPs by elderly patients.
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Academic Medical Centers↗
Biomedical subjects
M M Finkelstein
Publications and source records attributed to M M Finkelstein.
Cancer incidence among Ontario police officers.
The National Institute for Occupational Safety and Health (NIOSH) published a report in 1995 suggesting the possibility of increased incidence of testicular cancer, leukemia, and cancers of the brain, eye, and skin among police officers working with traffic radar. NIOSH recommended epidemiologic study of the issue. This report presents the results of a retrospective cohort cancer incidence study among 22,197 officers employed by 83 Ontario police departments. The standardized incidence ration (SIR) for all tumors sites was 0.9% (95% confidence interval [CI] = 0.83-0.98). There was an increased incidence of testicular cancer (SIR = 1.3, 90% CI = 0.9-1.8) and melanoma skin cancer (SIR = 1.45, 90% CI = 1.1-1.9). These anatomical sites might absorb energy from radar units, but at this time the author has no information about individual exposures to radar emissions, and it is not possible to draw etiologic conclusions. Nested case-control studies are planned to assess individual radar exposures.
Adult↗
Radiographic silicosis and lung cancer risk among workers in Ontario.
A case-control study, nested in a cohort of workers under surveillance for silicosis in 1979 or later, was undertaken to assess lung cancer risk in relation to the ILO coding scheme for the pneumoconioses. The subjects of this study are from the 41 matched quarters, consisting of one workers with silicosis and three age-matched controls, in which a lung cancer case was diagnosed. The odds ratio for lung cancer among subjects with ILO classification 1/0 or more, in comparison to subjects with category < or = 0/1, was 3.27 (95% CI =1.32-8.2). Adjustment of the radiographic risk for the effect of cumulative radon exposure had the effect of increasing the odds ratio for the association between ILO category > or = 1/0 and lung cancer. Although small smoking differences could account for the increased lung cancer odds ratio among workers with silicosis, the empirical evidence suggests that these smoking differences do not exist. It is concluded on the basis of two North American studies of silica exposed workers that radiographic silicosis is a marker for an increased risk of lung cancer.
Case-Control Studies↗
The relationship between parental occupation and bone cancer risk in offspring.
BACKGROUND: Bone cancers in children are serious and highly fatal conditions, yet relatively little is known about their causes or methods of prevention. METHODS: The relationship between parental occupation and bone cancer in offspring was explored in a case-control study. Cases were identified from the Ontario Cancer Registry; population-based controls were matched on sex and age. Data were collected from their parents through the use of a mailed self-administered questionnaire. RESULTS: The odds ratio estimates (OR) for bone cancer were elevated for fathers in the social sciences (OR = 2.5, 95% confidence interval [CI]: 0.7-8.4). Risk of Ewing's sarcoma was significantly high among children with fathers in social sciences (OR = 6.2, 95% CI: 1.6-24.5) and mothers in teaching (OR = 3.1, 95% CI: 1.1-8.7) or farming (OR = 7.8, 95% CI: 1.9-31.7). Osteosarcoma risk was increased for fathers in farming (OR = 2.1, 95% CI: 0.8-5.7), and mothers in managerial and administrative work (OR = 2.3, 95% CI: 0.6-8.1), and product fabricating, assembling, and repairing (OR = 2.0, 95% CI: 0.6-7.2). CONCLUSIONS: Certain methodological problems plague studies of bone cancer in children (e.g. small studies, low statistical power, analysis of multiple occupational categories, difficulty in identifying specific carcinogenic agents). These associations require further investigation, especially as elevated risks have been reported previously for agricultural occupations.
Adult↗
Is brain cancer an occupational disease of cardiologists?
OBJECTIVE: To assess the plausibility of radiation as a cause of the statistically unusual event of two cardiologists in Toronto, Ontario who were diagnosed with brain tumours in 1997. DESIGN: Computation of the expected occurrence of brain cancer in Ontario cardiologists and review of the epidemiological literature pertaining to radiation and brain cancer. DATA SYNTHESIS: The occurrence of these two cases is a statistically unusual event--a 'cluster'. There are several plausible explanations for this cluster. First, this may be a chance occurrence, and the tumours may have no causative factors in common. Second, the cause may be radiation exposure. A connection to occupational radiation exposure is biologically plausible, but risk assessment suggests that it is unlikely that this effect would have been observable in the small population of Ontario cardiologists. CONCLUSIONS: Initiation of brain tumours during cardiac fluoroscopic procedures is plausible. Physicians are reminded to practise radiation safety methods during fluoroscopic procedures. The diagnosis of two additional brain tumours in Canadian interventional cardiologists during the past 10 years would confirm the occupational causation theory. The author invites physicians to report knowledge of the diagnosis of brain tumours in Canadian cardiologists to the author or to the editors.
Aged↗
Radiographic asbestosis is not a prerequisite for asbestos-associated lung cancer in Ontario asbestos-cement workers.
In recent years, controversy has developed about whether pre-existing asbestosis is a prerequisite for the diagnosis of asbestos-related lung cancer. This paper presents the results of a prospective study, in a cohort of Ontario asbestos-cement workers, of lung cancer in relation to radiographs obtained 20 and 25 years from first exposure to asbestos. Radiographs were interpreted by a single NIOSH-certified "B" reader, and asbestosis was defined to mean an ILO code of 1/0 or greater. There were 143 subjects (123 without asbestosis, 20 with asbestosis), with a radiograph available for interpretation at 20 years from first exposure or later. The lung cancer standardized mortality ratio (SMR) among men without asbestosis at 20 years latency was 5.53 (95% CI: 2.9-9.7). There were 128 subjects (114 without asbestosis, 14 with asbestosis) with a radiograph available for interpretation at 25 years from first exposure or later. The lung cancer SMR among men without asbestosis at 25 years latency was 5.81 (95% CI 2.7-11). The results of this study are consistent with those of epidemiologic studies of asbestos-exposed populations in a variety of exposure situations. These studies have demonstrated that lung cancer risk is elevated in the presence of radiographic asbestosis, but they have also shown that lung cancer risk may be elevated in the absence of radiographic asbestosis.
Asbestos↗
Asbestos-associated cancers in the Ontario refinery and petrochemical sector.
Asbestos has been widely used in the refinery and petrochemical sector. Mesothelioma has occurred among maintenance employees, and it was hypothesized that mesothelioma is a marker for exposures which might increase lung cancer risk. A death certificate-based case-control study of mesothelioma and lung cancer from 1980 to 1992 was conducted in an Ontario county with a substantial presence of these industries. Each of the 17 men who died of mesothelioma and 424 with lung cancer were matched with controls who died of other causes. The Job and Industry fields on the death certificates were abstracted. Employment as a maintenance worker in the refinery and petrochemical sector was associated with an increased risk of mesothelioma (odds ratio: 24.5; 90% confidence interval 3.1-102). The risk of lung cancer among petrochemical workers, in comparison with all other workers in the county, was 0.88. In an internal comparison of maintenance employees with other blue-collar workers in the refinery and petrochemical sector, the odds ratio for lung cancer was 1.73 (90% confidence interval 0.83-3.6). This finding is consistent with no difference in risk between maintenance and other employees, but it is also compatible with study power being too low to achieve statistical significance. The hypothesis of increased lung cancer risk could be examined more fully with nested case-control studies in existing cohorts. Meanwhile, it would be prudent to reinforce adherence to asbestos control measures in the refinery and petrochemical sector.
Aged↗
Clinical measures, smoking, radon exposure, and risk of lung cancer in uranium miners.
OBJECTIVES: Exposure to the radioactive daughters of radon is associated with increased risk of lung cancer in mining populations. An investigation of incidence of lung cancer following a clinical survey of Ontario uranium miners was undertaken to explore whether risk associated with radon is modified by factors including smoking, radiographic silicosis, clinical symptoms, the results of lung function testing, and the temporal pattern of radon exposure. METHODS: Miners were examined in 1974 by a respiratory questionnaire, tests of lung function, and chest radiography. A random selection of 733 (75%) of the original 973 participants was followed up by linkage to the Ontario Mortality and Cancer Registries. RESULTS: Incidence of lung cancer was increased threefold. Risk of lung cancer among miners who had stopped smoking was half that of men who continued to smoke. There was no interaction between smoking and radon exposure. Men with lung function test results consistent with airways obstruction had an increased risk of lung cancer, even after adjustment for cigarette smoking. There was no association between radiographic silicosis and risk of lung cancer. Lung cancer was associated with exposures to radon daughters accumulated in a time window four to 14 years before diagnosis, but there was little association with exposures incurred earlier than 14 years before diagnosis. Among the men diagnosed with lung cancer, the mean and median dose rates were 2.6 working level months (WLM) a year and 1.8 WLM/year in the four to 14 year exposure window. CONCLUSIONS: Risk of lung cancer associated with radon is modified by dose and time from exposure. Risk can be substantially decreased by stopping smoking.
Air Pollutants, Radioactive↗
Radium in drinking water and risk of bone cancer in Ontario youths: a second study and combined analysis.
OBJECTIVES: Radium induces bone sarcomas at high doses, but there is controversy about risk at low doses. A previous study in Ontario found an association between the presence of radium in birthplace water supplies and an increased risk of death from bone cancer in young people. An investigation was performed to test the findings of the previous study with an independent group of subjects for whom complete information on radium exposure would be obtained. METHODS: A population based case-control study (238 cases; 432 controls) was conducted with incident cases of bone sarcoma identified from the Ontario cancer registry. Residential histories were collected by questionnaire and water samples were obtained and analysed for radium content. RESULTS: There was an association between risk of osteosarcoma and birthplace exposures (odds ratios (ORs) and 90% confidence intervals (90% CIs) 1.77 (1.03-3.00) but not with lifetime measures of exposure. When lifetime exposure was dichotomised, the OR was 1.31 (0.76-2.24) for osteosarcoma. There was no trend with increasing exposure. Bootstrap resampling was used to simulate lifetime doses in a pooled analysis of 1293 subjects from the two Ontario studies. The ORs were 1.38 (1.08-1.73) for all sarcomas, and 1.44 (1.01-1.87) for osteosarcoma. Geometric mean doses in bone were about 26 mRad. CONCLUSIONS: An association was found between the presence of radium in birthplace water supplies and increased risk of bone sarcoma in two studies. Increased risk was present for lifetime measures of exposure, but the association was not significant, and there was no dose-response trend. Our findings are compatible with the absence of risk at low doses, but they might also reflect inadequate statistical power to measure a true risk at environmental exposure levels. If the increased risk at environmental doses is causal, risk of bone sarcoma is effectively linearly related to dose over five orders of magnitude.
Adolescent↗
Radiographic abnormalities and the risk of lung cancer among workers exposed to silica dust in Ontario.
OBJECTIVE: To determine whether workers in Ontario who had been exposed to silica dust and who have radiographic abnormalities are at increased risk of lung cancer. DESIGN: Cohort and case-control studies of rates of death from lung cancer and cancer incidence rates; data were obtained from the Ontario Silicosis Surveillance Registry. Follow-up was through linkage to the Ontario mortality and cancer registries. SETTING: Ontario. PARTICIPANTS: A total of 523 workers with radiographic abnormalities and 1568 control subjects with normal radiographic findings who had been exposed to silica dust. Matching criteria were year of birth and the requirement that the control subject have a normal radiographic finding either later than or in the same year that the radiographic abnormality was identified in the silicosis subject. OUTCOME MEASURES: Standardized mortality ratios (SMRs), standardized incidence ratios (SIRs) and odds ratios for lung cancer. RESULTS: In the cohort analysis, with the Ontario population rates as reference, the all-cause SMR was 0.96 among the workers with radiographic abnormalities and 0.51 among the control subjects. The corresponding SIRs for lung cancer were 2.49 and 0.87 (p < 0.001). In the case-control analysis the workers with silicosis were more likely than the control subjects to have been smokers, but this difference likely accounted for only a small part of the difference in the incidence of lung cancer. The relative risk of lung cancer was elevated among the workers with silicosis from the foundry, mining and nonmetallic-minerals industries; however, the number of subjects was too small for a significant difference to be detected. Among the miners exposure to radon daughters did not affect the risk of lung cancer attributable to radiographic abnormalities. CONCLUSIONS: Radiographic abnormalities suggestive of exposure to silica dust are markers for increased risk of lung cancer. Physicians might thus wish to warn their patients with silica-associated radiographic abnormalities about the increased risk and to counsel those who smoke to stop.
Case-Control Studies↗
Occupational associations with lung cancer in two Ontario cities.
A death certificate based case-control study of lung cancer in two Ontario cities was performed to estimate the risk of lung cancer attributable to occupation in Ontario, and to estimate the proportion of occupational lung cancers receiving compensation from the Workers' Compensation Board. Occupation and industry were identified from the death certificate. A priori occupations for analysis were those whose members had received compensation for occupational cancer from the Ontario Workers' Compensation Board. Population attributable risks were computed using the relative risks observed in this study and employment data from the 1986 Census of Canada. Subjects were all men (N = 967) between the ages of 45 and 75 years resident in the cities of Hamilton and Sault Ste-Marie who died of lung cancer from 1979 to 1988. Controls (2,821) were matched on age, year of death, and city of residence. In agreement with other studies, an increased risk of lung cancer was observed for workers in the construction sector, for miners, and for truck drivers. It was estimated that only a small proportion of lung cancers attributable to occupation are compensated in Ontario. It is believed that many occupational cancers go uncompensated because of the failure to file claims, rather than because claims are rejected by Compensation Boards. Physicians are in a position to advise patients about the possibility of compensable disease and to act as advocates for them. By recognizing compensable illness, physicians have the opportunity to ease the financial burden of patients and their families. The challenge is a difficult one, but it is well worth pursuing.
Aged↗
Potential pitfall in using cumulative exposure in exposure-response relationships: demonstration and discussion.
Cumulative exposure is frequently used as a measure of exposure in the quantitative analysis of epidemiologic studies. It is recognized that the imposed symmetry between duration and intensity of exposure is a potential problem with this measure, but it is less widely recognized that the finding of an exposure-response relationship, using cumulative exposure as the exposure metric, does not necessarily imply that exposures were accurately or even consistently estimated. This report describes a simulation study drawn from a nested case-control analysis of mesothelioma in a cohort of asbestos cement workers. Intensity of exposure in the range of 0.1-40 fibers/ml was randomly assigned to subjects. Logistic regression analysis demonstrated that there was no association between mesothelioma risk and the randomly assigned intensity of exposure. However, in 171 (86%) of 200 trials, mesothelioma risk was significantly associated with cumulative exposure, even though intensity of exposure remained randomly assigned. A strong exposure-response relationship might thus be misleading. One would be more confident about quantitative risk assessment when there are a large number of independent studies available for analysis.
Asbestos↗
Silicosis, radon, and lung cancer risk in Ontario miners.
The presence of radiographic silicosis was assessed as a risk factor for lung cancer in a cohort and case-control study of miners in the Ontario Silicosis Surveillance Database. Subjects were 328 miners with silicosis matched on age to 970 miners with normal radiographs. In a cancer incidence follow-up, there was a significant excess of lung cancer among miners with silicosis (Standardized Incidence Ratio 2.55; 95% Confidence Interval 1.43-8.28). Miners with normal radiographs had lung cancer incidence about the same as the Ontario average (Standardized Incidence Ratio 0.90; 95% Confidence Interval 0.51-1.47). In a matched case-control analysis of lung cancer, cumulative radon exposure was associated with lung cancer risk (increase in odds ratio 0.4% per WLM; 95% Confidence Interval -0.3% to 1.1%). When the presence of silicosis was added to the model, silicosis was a highly significant risk factor for lung cancer (Odds Ratio 6.99 95% Confidence Interval 1.91-25) and the risk factor for radon was diminished (increase in Odds Ratio -0.5% per WLM; 95% confidence Interval -1.4% to 0.4%). This finding suggests that additional study is warranted before concluding that radon risk factors derived from mining populations do not need to be modified for application to the general population.
Case-Control Studies↗
Back pain and parenthood.
OBJECTIVE: To test the hypothesis that reports of back pain in a working population are associated with parenthood. METHODS: A questionnaire survey of back pain in municipal fire fighters and police officers in a municipality in Ontario, Canada. The questionnaire was distributed to current employees of fire and police departments. The survey was completed by 129 fire fighters (68% of the active force) and 346 police officers (74% of the force). RESULTS: 36% of the respondents complained of a back problem. The prevalence increased from 13% among men aged 19 to 28 to 47% among men aged 49 to 59. The complaint was more common among firefighters (42%) than among police officers (33%). In a logistic regression analysis, back problems were significantly associated with the duration of employment, cigarette smoking, and the number of children. CONCLUSIONS: Back pain is a multifactorial problem with significant impact on the working population. This survey has found that parenthood, a risk factor not previously described among men, is associated with self reported back pain. The mechanism presumably involves lifting of children or recreational factors. Fatherhood seems to be a confounder that should be controlled for in studies of occupational causes of back pain.
Adult↗
Does occupational exposure to dust prevent colorectal cancer?
OBJECTIVES: To explore the impression that occupational epidemiologists tend to focus on associations suggestive of increased risk and tend to ignore those associations in which risk is not increased. To examine the risk of colorectal cancer in cohorts exposed to dust, cohorts in which it has been suggested that occupational exposure is a cause of increased risk of stomach cancer. METHODS: A review of the publications in the English language on mortality among hard rock miners, granite, and quarry workers identified from a MEDLINE search and the index of the library of the Ontario Ministry of Labour. RESULTS: When all of the studies were combined, there were significant excesses of lung and stomach cancers, but a significant deficit of colorectal cancer (standardised mortality ratio (SMR) = 83.9; 95% confidence interval (95% CI) 76-91). Overall mortality from gastrointestinal cancer was close to expectation (SMR = 105; 95% CI 99-111). Among those cohorts with increased risk of stomach cancer, rates of colorectal cancer were significantly decreased (SMR = 80; 95% CI 72-88). Among cohorts without increased risk of stomach cancer, the SMR for colorectal cancer was not significantly different from 100 (SMR = 98; 95% CI 81-115). CONCLUSIONS: This review supports the impression that occupational epidemiologists tend to focus on associations suggestive of increased risk and tend to ignore those associations in which risk is not increased. The explanation for the inverse association between risk of stomach and colorectal cancer is uncertain and deserves further study.
Colonic Neoplasms↗
Silicosis surveillance in Ontario from 1979 to 1992.
This paper reports the detection rates of silicosis among silica-exposed persons first exposed to dust in 1950 or later and still employed in 1979 or later in the province of Ontario. The rate varied strongly with latency, being less than two new cases per 10 000 examinations during the first two decades from first exposure, reaching two new cases per 1000 examinations at 27 years from first exposure, and averaging between two and four new cases per 1000 examinations thereafter. A Poisson regression analysis found that the silicosis rate in the interval after 30 years from first exposure was more than 16 times higher than the rate prior to 20 years from first exposure. There was no significant difference in the diagnosis rates among the workers in the mining, primary metal, and nonmetallic mineral industries sectors. The rate of silicosis was higher among smokers than among never smokers (rate ratio 1.54).
Confidence Intervals↗
Radium in drinking water and the risk of death from bone cancer among Ontario youths.
OBJECTIVE: To determine whether residents of Ontario who are exposed to radium 226 naturally occurring in drinking water are at increased risk of bone cancer. DESIGN: A population-based case-control study of records from death and birth registries. Water samples were obtained from residences at the time of birth and of death. SETTING: Ontario. PARTICIPANTS: All Ontario-born people under the age of 26 years who died of bone cancer between 1950 and 1983. Control subjects were those who died of any other disease matched by age, sex and year of death. OUTCOME MEASURES: Radium exposure distributions and estimation of risk. RESULTS: An association was found between death from bone cancer and exposure to radium at the birthplace residence in concentrations of 7.0 mBq/L or more (odds ratio 1.58, 90% confidence interval [CI] 1.01 to 2.50; p = 0.047). There was a statistically significant exposure-response relation (p = 0.045). The increase in risk was similar for the main types of childhood bone cancer: osteosarcoma, Ewing's sarcoma and chondrosarcoma. CONCLUSIONS: The estimated risk at these exposure levels is much higher than would be predicted. The association may be spurious, the point estimates of risk may be too high, or risk factors derived from other exposure circumstances may not be valid for exposure to radium beginning in the prenatal period. Should the findings be confirmed, consideration might be given to removing radium from drinking-water sources.
Adolescent↗
Compensating occupational diseases.
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Canada↗