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Biomedical subjects

M M Finkelstein

Publications and source records attributed to M M Finkelstein.

At least 19 recordsLinked to original sources
PubMed1999

Inferences on the kinetics of asbestos deposition and clearance among chrysotile miners and millers.

BACKGROUND: The health effects of asbestos are intimately related to the fate of inhaled fibers in the lungs. The kinetics of asbestos fibers have been studied primarily in rodents. The objective of this study was to explore the application of these kinetic models to human autopsy data. METHODS: We analyzed the asbestos fiber content of the lungs of 72 Quebec chrysotile miners and millers and 49 control subjects using analytical transmission electron microscopy. Statistical methods included standard multivariate linear regression and locally weighted regression methods. RESULTS: The lung burdens of asbestos bodies and chrysotile and tremolite fibers were correlated, as were the concentrations of short, medium, and long fibers of each asbestos variety. There were significant associations between the duration of occupational exposure and the burdens of chrysotile and tremolite. The concentration of chrysotile decreased with the time since last exposure but the concentration of tremolite did not. The clearance rate varied inversely with the length of chrysotile fibers. For fibers greater than 10 mu in length the clearance half-time was estimated to be 8 years. CONCLUSIONS: The patterns in our data are compatible with both of the hypotheses suggested from rodent experiments; the existence of a long-term sequestration compartment and overload of clearance mechanisms in this compartment.

Aged↗
PubMed1999

Record linkage as a research tool for office-based medical care.

OBJECTIVE: To explore the feasibility of linking records to study health services and health outcomes for primary care patients. DESIGN: A cohort of patients from the Family Medicine Centre at Mount Sinai Hospital was assembled from the clinic's billing records. Their health numbers were linked to the Ontario Hospital Discharge Database. The pattern of hospital admission rates was investigated using International Classification of Diseases (ICD) codes for primary discharge diagnosis. A pilot case-control study of risk factor management for stroke was nested in the cohort. SETTING: Family medicine clinic based in a teaching hospital. PARTICIPANTS: A cohort of 19,654 Family Medicine Centre patients seen at least once since 1991. MAIN OUTCOME MEASURES: Admission rates by age, sex, and diagnosis. Numbers of admissions for individual patients, time to readmission, and length of stay. Odds ratios for admission for cerebrovascular disease. RESULTS: The 19,654 patients in the cohort had 14,299 discharges from Ontario hospitals in the 4 years from 1992 to 1995, including 3832 discharges following childbirth. Some patients had many discharges: 4816 people accounted for the 10,467 admissions excluding childbirth. Excluding transfers between institutions, there were 4975 readmissions to hospital during the 4 years, 1392 (28%) of them within 28 days of previous discharge. Admissions for mental disorders accounted for the greatest number of days in hospital. The pilot study of risk factor management suggested that acetylsalicylic acid therapy might not be effective for elderly primary care patients with atrial fibrillation and that calcium channel blocker therapy might be less effective than other therapies for preventing cerebrovascular disease in hypertensive primary care patients. CONCLUSIONS: Record linkage combined with data collection by chart review or interview is a useful method for studying the effectiveness of medical care in Canada and might suggest interesting hypotheses for further investigation.

Adolescent↗
PubMed1998

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↗
PubMed1998

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↗
PubMed1998

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↗
PubMed1998

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↗
PubMed1997

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↗
PubMed1996

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↗
PubMed1996

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↗
PubMed1996

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↗
PubMed1995

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↗