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34 records – page 1 of 4.

Adjusting for temporal variation in the analysis of parallel time series of health and environmental variables.

https://arctichealth.org/en/permalink/ahliterature205764
Source
J Expo Anal Environ Epidemiol. 1998 Apr-Jun;8(2):129-44
Publication Type
Article
Author
S. Cakmak
R. Burnett
D. Krewski
Author Affiliation
Health Protection Branch, Health Canada, Ottawa, Ontario, Canada. scakmak@ehd.hwc.ca
Source
J Expo Anal Environ Epidemiol. 1998 Apr-Jun;8(2):129-44
Language
English
Publication Type
Article
Keywords
Air Pollution - adverse effects - analysis
Environmental Exposure - analysis
Hospitalization
Humans
Lung Diseases - etiology
Models, Statistical
Ontario
Ozone - adverse effects
Public Health
Temperature
Time Factors
Abstract
Time series of daily administrative cardio-respiratory health and environmental information have been extensively used to assess the potential public health impact of ambient air pollution. Both series are subject to strong but unrelated temporal cycles. These cycles must be removed from the time series prior to examining the role air pollution plays in exacerbating cardio-respiratory disease. In this paper, we examine a number of methods of temporal filtering that have been proposed to eliminate such temporal effects. The techniques are illustrated by linking the number of daily admissions to hospital for respiratory diseases in Toronto, Canada for the 11 year period 1981 to 1991 with daily concentrations of ambient ozone. The ozone-hospitalization relationship was found to be highly sensitive to the length of temporal cycle removed from the admission time series, and to day of the week effects, ranging from a relative risk of 0.874 if long wave cycles were not removed at all to 1.020 for models which removed at least cycles greater than or equal to one month based on the interquartile pollutant range. The specific statistical method of adjustment was not a critical factor. The association was not as sensitive to removal of cycles less than one month, except that negative autocorrelation increased for series in which cycles of one week or less were removed. We recommend three criteria in selecting the degree of smoothing in the outcome: removal of temporal cycles, minimizing autocorrelation and optimizing goodness of fit. The association between ambient ozone levels and hospital admissions for respiratory diseases was also sensitive to the season of examination, with weaker associations observed outside the summer months.
PubMed ID
9577746 View in PubMed
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Are the apparent effects of cigarette smoking on lung and bladder cancers due to uncontrolled confounding by occupational exposures?

https://arctichealth.org/en/permalink/ahliterature219248
Source
Epidemiology. 1994 Jan;5(1):57-65
Publication Type
Article
Date
Jan-1994
Author
J. Siemiatycki
R. Dewar
D. Krewski
M. Désy
L. Richardson
E. Franco
Author Affiliation
Epidemiology and Biostatistics Unit, Institut Armand-Frappier, Université du Québec, Laval-des-Rapides, Canada.
Source
Epidemiology. 1994 Jan;5(1):57-65
Date
Jan-1994
Language
English
Publication Type
Article
Keywords
Adult
Aged
Canada - epidemiology
Case-Control Studies
Confounding Factors (Epidemiology)
Environment
Epidemiologic Methods
Humans
Incidence
Lung Neoplasms - epidemiology - etiology
Male
Middle Aged
Occupational Exposure - adverse effects - statistics & numerical data
Odds Ratio
Smoking - adverse effects - epidemiology
Urinary Bladder Neoplasms - epidemiology - etiology
Abstract
It has been suggested that the well known associations between smoking and cancer may in part reflect inadequately controlled confounding due to occupational exposures. The purpose of the present analysis is to describe the association between cigarette smoking and both lung and bladder cancers, taking into account the potential confounding effects of over 300 covariates, most of which represent occupational exposures. A population-based case-control study was undertaken in Montreal to investigate the associations between a large variety of environmental and occupational exposures, on the one hand, and several types of cancer, on the other. Interviews were carried out with male incident cases of several sites of cancer, including 857 lung cancers and 484 bladder cancers. A group of non-smoking-related cancers, comprising 1,707 interviewed subjects, was used as one control group. Additionally, 533 population controls were interviewed and constituted a second control group. Interview information included detailed lifetime smoking histories, job histories, and other potential confounders. Each job history was reviewed by a team of experts who translated it into a history of occupational exposures. These occupational exposures, as well as nonoccupational covariates, were treated as potential confounders in the analysis of cigarette smoking effects. Regardless of whether population controls or cancer controls were used, the odds ratio (OR) between smoking and lung cancer (ranging from 12 to 16 for ever vs never smokers) was not materially affected by adjustment for occupational exposures. The odds ratios for bladder cancer (ranging from 2 to 3) were also unaffected by confounding due to occupational exposures.(ABSTRACT TRUNCATED AT 250 WORDS)
PubMed ID
8117783 View in PubMed
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The association between ambient carbon monoxide levels and daily mortality in Toronto, Canada.

https://arctichealth.org/en/permalink/ahliterature204570
Source
J Air Waste Manag Assoc. 1998 Aug;48(8):689-700
Publication Type
Article
Date
Aug-1998
Author
R T Burnett
S. Cakmak
M E Raizenne
D. Stieb
R. Vincent
D. Krewski
J R Brook
O. Philips
H. Ozkaynak
Author Affiliation
Health Protection Branch, Health Canada, Ottawa, Ontario, Canada.
Source
J Air Waste Manag Assoc. 1998 Aug;48(8):689-700
Date
Aug-1998
Language
English
Publication Type
Article
Keywords
Aged
Aged, 80 and over
Air Pollutants, Occupational - analysis
Carbon Monoxide - analysis
Heart Diseases - mortality
Humans
Mortality
Ontario - epidemiology
Abstract
The role of ambient levels of carbon monoxide (CO) in the exacerbation of heart problems in individuals with both cardiac and other diseases was examined by comparing daily variations in CO levels and daily fluctuations in nonaccidental mortality in metropolitan Toronto for the 15-year period 1980-1994. After adjusting the mortality time series for day-of-the-week effects, nonparametic smoothed functions of day of study and weather variables, statistically significant positive associations were observed between daily fluctuations in mortality and ambient levels of carbon monoxide, nitrogen dioxide, sulfur dioxide, coefficient of haze, total suspended particulate matter, sulfates, and estimated PM2.5 and PM10. However, the effects of this complex mixture of air pollutants could be almost completely explained by the levels of CO and total suspended particulates (TSP). Of the 40 daily nonaccidental deaths in metropolitan Toronto, 4.7% (95% confidence interval of 3.4%-6.1%) could be attributable to CO while TSP contributed an additional 1.0% (95% confidence interval of 0.2-1.9%), based on changes in CO and TSP equivalent to their average concentrations. Statistically significant positive associations were observed between CO and mortality in all seasons, age, and disease groupings examined. Carbon monoxide should be considered as a potential public health risk to urban populations at current ambient exposure levels.
PubMed ID
9739623 View in PubMed
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Association between ambient carbon monoxide levels and hospitalizations for congestive heart failure in the elderly in 10 Canadian cities.

https://arctichealth.org/en/permalink/ahliterature209090
Source
Epidemiology. 1997 Mar;8(2):162-7
Publication Type
Article
Date
Mar-1997
Author
R T Burnett
R E Dales
J R Brook
M E Raizenne
D. Krewski
Author Affiliation
Environmental Health Directorate, Health Canada, Ottawa, Canada.
Source
Epidemiology. 1997 Mar;8(2):162-7
Date
Mar-1997
Language
English
Publication Type
Article
Keywords
Aged
Air Pollutants - adverse effects
Canada - epidemiology
Carbon Monoxide - adverse effects - analysis
Cohort Studies
Dose-Response Relationship, Drug
Environmental monitoring
Epidemiological Monitoring
Female
Health Care Surveys
Heart Failure - epidemiology - etiology - therapy
Hospitalization - statistics & numerical data - trends
Humans
Incidence
Linear Models
Male
Regression Analysis
Risk assessment
Abstract
We examined the role that ambient air pollution plays in exacerbating cardiac disease by relating daily fluctuations in admissions to 134 hospitals for congestive heart failure in the elderly to daily variations in ambient concentrations of carbon monoxide, nitrogen dioxide, sulfur dioxide, ozone, and the coefficient of haze in Canada's 10 largest cities for the 11-year period 1981-1991 inclusive. We adjusted the hospitalization time series for seasonal, subseasonal, and weekly cycles and for hospital usage patterns. The logarithm of the daily high-hour ambient carbon monoxide concentration recorded on the day of admission displayed the strongest and most consistent association with hospitalization rates among the pollutants, after stratifying the time series by month of year and adjusting simultaneously for temperature, dew point, and the other ambient air pollutants. The relative risk for a change from 1 ppm to 3 ppm, the 25th and 75th percentiles of the exposure distribution, was 1.065 (95% confidence interval = 1.028-1.104). The regression coefficients of the other air pollutants were much more sensitive to simultaneous adjustment for either multiple pollutant or weather model specifications.
PubMed ID
9229208 View in PubMed
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Association between ozone and hospitalization for acute respiratory diseases in children less than 2 years of age.

https://arctichealth.org/en/permalink/ahliterature195575
Source
Am J Epidemiol. 2001 Mar 1;153(5):444-52
Publication Type
Article
Date
Mar-1-2001
Author
R T Burnett
M. Smith-Doiron
D. Stieb
M E Raizenne
J R Brook
R E Dales
J A Leech
S. Cakmak
D. Krewski
Author Affiliation
Environmental Health Directorate, Health Canada, 200 Environmental Health Center, Tunney's Pasture, Ottawa, Ontario, Canada K1A OL2. rick_burnett@hc-sc.gc.ca
Source
Am J Epidemiol. 2001 Mar 1;153(5):444-52
Date
Mar-1-2001
Language
English
Publication Type
Article
Keywords
Acute Disease
Air Pollution - adverse effects
Child, Hospitalized - statistics & numerical data
Female
Hospitalization - statistics & numerical data
Humans
Infant
Infant, Newborn
Male
Ontario - epidemiology
Ozone - adverse effects
Respiratory Tract Diseases - epidemiology - etiology
Risk factors
Seasons
Urban Health - statistics & numerical data
Abstract
To clarify the health effects of ozone exposure in young children, the authors studied the association between air pollution and hospital admissions for acute respiratory problems in children less than 2 years of age during the 15-year period from 1980 to 1994 in Toronto, Canada. The daily time series of admissions was adjusted for the influences of day of the week, season, and weather. A 35% (95% confidence interval: 19%, 52%) increase in the daily hospitalization rate for respiratory problems was associated with a 5-day moving average of the daily 1-hour maximum ozone concentration of 45 parts per billion, the May-August average value. The ozone effect persisted after adjustment for other ambient air pollutants or weather variables. Ozone was not associated with hospital admissions during the September-April period. Ambient ozone levels in the summertime should be considered a risk factor for respiratory problems in children less than 2 years of age.
PubMed ID
11226976 View in PubMed
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Association between ozone and hospitalization for respiratory diseases in 16 Canadian cities.

https://arctichealth.org/en/permalink/ahliterature210280
Source
Environ Res. 1997 Jan;72(1):24-31
Publication Type
Article
Date
Jan-1997
Author
R T Burnett
J R Brook
W T Yung
R E Dales
D. Krewski
Author Affiliation
Health Canada, Environmental Health Center, Tunney's Pasture, Ottawa, Ontario, Canada. rick-burnett@isdtcp3.hwc.ca
Source
Environ Res. 1997 Jan;72(1):24-31
Date
Jan-1997
Language
English
Publication Type
Article
Keywords
Air Pollutants
Canada
Hospitalization - trends
Humans
Longitudinal Studies
Ozone - adverse effects
Regression Analysis
Respiratory Function Tests
Respiratory Tract Diseases - epidemiology
Retrospective Studies
Risk assessment
Abstract
The effects of tropospheric ozone on lung function and respiratory symptoms have been well documented at relatively high concentrations. However, previous investigations have failed to establish a clear association between tropospheric ozone and respiratory diseases severe enough to require hospitalization after controlling for climate, and with gaseous and particulate air pollution at the lower concentrations typically observed in Canada today. To determine if low levels of tropospheric ozone contribute to hospitalization for respiratory disease, air pollution data were compared to hospital admissions for 16 cities across Canada representing 12.6 million people. During the 3927-day period from April 1, 1981, to December 31, 1991, there were 720,519 admissions for which the principle diagnosis was a respiratory disease. After controlling for sulfur dioxide, nitrogen dioxide, carbon monoxide, soiling index, and dew point temperature, the daily high hour concentration of ozone recorded 1 day previous to the date of admission was positively associated with respiratory admissions in the April to December period but not in the winter months. The relative risk for a 30 ppb increase in ozone varied from 1.043 (P
PubMed ID
9012369 View in PubMed
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Association between particulate- and gas-phase components of urban air pollution and daily mortality in eight Canadian cities.

https://arctichealth.org/en/permalink/ahliterature184322
Source
Inhal Toxicol. 2000;12 Suppl 4:15-39
Publication Type
Article
Date
2000
Author
R T Burnett
J. Brook
T. Dann
C. Delocla
O. Philips
S. Cakmak
R. Vincent
M S Goldberg
D. Krewski
Author Affiliation
Environmental Health Directorate, Health Canada, Ottawa, and Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Canada. rick_burnett@hc-sc.gc.ca
Source
Inhal Toxicol. 2000;12 Suppl 4:15-39
Date
2000
Language
English
Publication Type
Article
Keywords
Air Pollutants - adverse effects
Air Pollution - adverse effects
Canada - epidemiology
Cities
Humans
Logistic Models
Mortality - trends
Urban Population - statistics & numerical data
Weather
Abstract
Although some consensus has emerged among the scientific and regulatory communities that the urban ambient atmospheric mix of combustion related pollutants is a determinant of population health, the relative toxicity of the chemical and physical components of this complex mixture remains unclear. Daily mortality rates and concurrent data on size-fractionated particulate mass and gaseous pollutants were obtained in eight of Canada's largest cities from 1986 to 1996 inclusive in order to examine the relative toxicity of the components of the mixture of ambient air pollutants to which Canadians are exposed. Positive and statistically significant associations were observed between daily variations in both gas- and particulate-phase pollution and daily fluctuations in mortality rates. The association between air pollution and mortality could not be explained by temporal variation in either mortality rates or weather factors. Fine particulate mass (less than 2.5 microns in average aerometric diameter) was a stronger predictor of mortality than coarse mass (between 2.5 and 10 microns). Size-fractionated particulate mass explained 28% of the total health effect of the mixture, with the remaining effects accounted for by the gases. Forty-seven elemental concentrations were obtained for the fine and coarse fraction using nondestructive x-ray fluorescence techniques. Sulfate concentrations were obtained by ion chromatography. Sulfate ion, iron, nickel, and zinc from the fine fraction were most strongly associated with mortality. The total effect of these four components was greater than that for fine mass alone, suggesting that the characteristics of the complex chemical mixture in the fine fraction may be a better predictor of mortality than mass alone. However, the variation in the effects of the constituents of the fine fraction between cities was greater than the variation in the mass effect, implying that there are additional toxic components of fine particulate matter not examined in this study whose concentrations and effects vary between locations. One of these components, carbon, represents half the mass of fine particulate matter. We recommend that measurements of elemental and organic carbon be undertaken in Canadian urban environments to examine their potential effects on human health.
PubMed ID
12881885 View in PubMed
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Associations between ambient particulate sulfate and admissions to Ontario hospitals for cardiac and respiratory diseases.

https://arctichealth.org/en/permalink/ahliterature214790
Source
Am J Epidemiol. 1995 Jul 1;142(1):15-22
Publication Type
Article
Date
Jul-1-1995
Author
R T Burnett
R. Dales
D. Krewski
R. Vincent
T. Dann
J R Brook
Author Affiliation
Health Protection Branch, Health Canada, Tunney's Pasture, Ottawa, Ontario.
Source
Am J Epidemiol. 1995 Jul 1;142(1):15-22
Date
Jul-1-1995
Language
English
Publication Type
Article
Keywords
Adult
Aged
Air Pollutants - adverse effects - analysis
Air Pollution - statistics & numerical data
Environmental Exposure - adverse effects - analysis
Female
Heart Diseases - chemically induced - epidemiology
Hospitalization - statistics & numerical data
Humans
Longitudinal Studies
Male
Middle Aged
Ontario - epidemiology
Ozone
Regression Analysis
Respiratory Tract Diseases - chemically induced - epidemiology
Seasons
Sulfates - adverse effects - analysis
Abstract
The association of daily cardiac and respiratory admissions to 168 acute care hospitals in Ontario, Canada, with daily levels of particulate sulfates was examined over the 6-year period 1983-1988. Sulfate levels were recorded at nine monitoring stations in regions of southern and central Ontario spanned by three monitoring networks. A 13-micrograms/m3 increase in sulfates recorded on the day prior to admission (the 95th percentile) was associated with a 3.7% (p
PubMed ID
7785669 View in PubMed
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Associations between cigarette smoking and each of 21 types of cancer: a multi-site case-control study.

https://arctichealth.org/en/permalink/ahliterature215016
Source
Int J Epidemiol. 1995 Jun;24(3):504-14
Publication Type
Article
Date
Jun-1995
Author
J. Siemiatycki
D. Krewski
E. Franco
M. Kaiserman
Author Affiliation
Institut Armand-Frappier, Université du Québec, Laval-des-Rapides, Canada.
Source
Int J Epidemiol. 1995 Jun;24(3):504-14
Date
Jun-1995
Language
English
Publication Type
Article
Keywords
Adult
Aged
Case-Control Studies
Humans
Male
Middle Aged
Neoplasms - epidemiology - etiology
Quebec - epidemiology
Questionnaires
Risk factors
Smoking - adverse effects
Time Factors
Abstract
Although the effects of cigarette smoking on cancer risk have been well documented, there remain several outstanding issues to be clarified, including the determination of which types of cancer are associated with smoking and estimation of the magnitude of the effect of smoking on different types of cancer. A further issue is whether the effects seen elsewhere can be demonstrated in Canada, where tobacco products differ somewhat from those in other countries.
A case-control study was undertaken in Montreal to investigate the associations between a large number of environmental and occupational exposures on the one hand, and several types of cancer on the other. Between 1979 and 1985, interviews were carried out with incident male cases of 21 types of cancer, including 15 anatomical sites and six histological subtypes. The interview was designed to obtain detailed information on smoking histories, job histories, and other potential confounders. Altogether, 3730 cancer patients and 533 population controls were interviewed. For each type of cancer analysed, two control groups were used: population controls and cancer controls (selected from among other cancer patients). The purpose of the present analysis is to estimate the relative risk of each of 21 types of cancer in relation to smoking and to estimate the percentage of cancer cases attributable to cigarette smoking.
Separate analyses conducted with the two control groups produced similar results. Of the many sites of cancer examined, the following were not associated with cigarette smoking: colon, rectum, liver, prostate, kidney and skin (melanoma). Within the lymphoreticular system, there was no excess risk of Hodgkin's lymphoma, although the results for non-Hodgkin's lymphoma were weakly suggestive of an association with smoking. The following sites were clearly associated with smoking: lung (odds ratio [OR] = 12.1), bladder (OR = 2.4), oesophagus (OR = 2.4), stomach (OR = 1.7), and pancreas (OR = 1.6). Population attributable risk percentages due to smoking were 90% for lung, 53% for bladder, 54% for oesophagus, 35% for stomach, and 33% for pancreas.
Of the 21 types of cancer examined, the following were associated with smoking among men in Montreal: lung (including all major histological subtypes), bladder (and its main histological subtypes), oesophagus, stomach and pancreas. Smoking likely accounts for a large proportion of cancers occurring at these sites.
PubMed ID
7672889 View in PubMed
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Associations between several sites of cancer and occupational exposure to benzene, toluene, xylene, and styrene: results of a case-control study in Montreal.

https://arctichealth.org/en/permalink/ahliterature205226
Source
Am J Ind Med. 1998 Aug;34(2):144-56
Publication Type
Article
Date
Aug-1998
Author
M. Gérin
J. Siemiatycki
M. Désy
D. Krewski
Author Affiliation
Départment de médecine du travail et d'hygiène du milieu, Université de Montréal, Québec, Canada.
Source
Am J Ind Med. 1998 Aug;34(2):144-56
Date
Aug-1998
Language
English
Publication Type
Article
Keywords
Adult
Aged
Benzene - adverse effects
Case-Control Studies
Confidence Intervals
Humans
Hydrocarbons, Aromatic - adverse effects
Male
Middle Aged
Neoplasms - chemically induced - epidemiology
Occupational Diseases - chemically induced - epidemiology
Occupational Exposure - adverse effects
Odds Ratio
Quebec - epidemiology
Questionnaires
Risk factors
Styrene
Styrenes - adverse effects
Toluene - adverse effects
Xylenes - adverse effects
Abstract
Except for the leukemogenic effects of benzene, there is inadequate or sparse evidence on the carcinogenicity of the most common monocyclic aromatic hydrocarbons. The purpose of this study was to generate hypotheses on associations between exposure to benzene, toluene, xylene, and styrene and various common types of cancer.
In the context of a population-based case-control study carried out in Montreal, 3,730 cancer patients (15 types of cancers, not including leukemia) and 533 population controls were interviewed, and their job histories were translated by a team of experts into occupational exposures, including benzene, toluene, xylene, and styrene. In the present analysis, exposure to these substances was compared between each case series and a control group pooling selected cancer patients and population controls, using logistic regression analysis.
Exposure levels were low for most exposed subjects, and there was a high correlation between exposure to benzene, toluene and xylene. For most sites of cancer there was no evidence of excess risk due to these substances. However, limited evidence of increased risk was found for the following associations: esophagus-toluene, colon-xylene, rectum-toluene, rectum-xylene and rectum-styrene.
These latter observations warrant further investigation.
PubMed ID
9651624 View in PubMed
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34 records – page 1 of 4.