Ambient PM2.5, O3, and NO2 Exposures and Associations with Mortality over 16 Years of Follow-Up in the Canadian Census Health and Environment Cohort (CanCHEC)

Exposure to traffic and mortality risk in the 1991–2011 Canadian Census Health and Environment Cohort (CanCHEC)

The Canadian Census Health and Environment Cohort (CanCHEC) was developed to advance the scientific knowledge about the impacts of prolonged exposure to low-levels of ambient air pollution. Initially, this large-scale cohort consisted of the 20% of Canadian households who were mandated to complete the more detailed long-form census in 1991. Dr. Burnett played a prominent role in the development of the cohort which has since been extended to include those who completed the long-form census in 1996, 2001, and 2006. Probabilistic record linkage of these cohorts were undertaken to link these individuals to Canadian income tax, mortality and cancer registry data. Linkages to the tax databases allowed for the determination of place of residence on an annual basis. Combined, these cohorts include nearly 13 million Canadians (37%) and approximately 1.7 million deaths identified during follow-up. Estimates of ambient air pollution concentrations have been assigned to cohort subjects based on their residential postal codes using a variety of methods including fixed-site monitoring, land use regression, and remote sensing techniques. Analyses of the CanCHEC have provided insights on how long term-exposure to low levels of ambient pollution is associated with cause-specific mortality. This presentation will highlight the contributions of Dr. Burnett with respect to the major research findings for air pollution that have been obtained from this cohort. These include estimates for associations between ambient air pollution concentration and mortality with respect to: (i) the shape of the exposure-response curve, (ii) oxidative burden of fine particulate matter, (iii) methods to indirectly adjust for the impacts of missing covariates, and (iv) methods to account for within- and between-city variations in risk. Lastly, this presentation will highlight ongoing and future research activities using the CanCHEC.

Ozone exposure and cardiovascular-related mortality in the Canadian Census Health and Environment Cohort (CANCHEC) by spatial synoptic classification zone

S13: How Low Should We Go? New Health Research on Low-level Ambient Air Pollution, Beatrix Theater, August 28, 2019, 1:30 PM - 3:00 PM Background/Aims Fine particulate matter (PM2.5) is associated with mortality, however the range of applicable concentrations is unknown. We applied novel satellite-based estimates of PM2.5 exposure to large population-based cohorts, and characterized the shape of the mortality relationship, with emphasis on the low concentrations (<12 µg/m3) observed throughout Canada. Methods Annual satellite-based PM2.5 exposure estimates were developed at 1 km resolution across Canada for 1998-2016 and back-casted to 1981 using remote sensing, chemical transport models and ground monitoring data. Exposures were estimated for ~8.5 million subjects in three Canadian Census Health and Environment Cohort (CanCHEC) cohorts, and 540,900 Canadian Community Health Survey (CCHS) participants, based on residential histories derived from annual tax records. Mortality was linked until 2016. Sensitivity analyses evaluated adjustment for (individual/contextual/geographic) covariates and gaseous (NO2, ozone) co-pollutants; exposure time windows and spatial scale. Estimates were evaluated across strata of age, sex and immigrant status and the shape of the PM2.5 and mortality association was examined with the Shape Constrained Health Impact Function (SCHIF). Results Satellite-based PM2.5 estimates were low (mean 3-year averages of 7.4μg/m3 and 5.9 µg/m3 in CanCHEC and CCHS, respectively) and highly correlated with ground monitors (R2 = 0.82, RMSE=1.5 µg/m3). In final adjusted models non-accidental mortality hazard ratios (HR) per 10µg/m3 change in PM2.5 were 1.04 (95% CI: 1.04-1.05) in CanCHEC and 1.11 (95% CI 1.04-1.18) in CCHS. In CanCHEC the SCHIF predicted a sublinear concentration-mortality curve with little increased risk below 5 g/m3, and monotonically increased HRs above this concentration. In CCHS we estimated a supra-linear relationship to concentrations below 2µg/m3. HRs were larger for females, younger ages and non-immigrants and attenuated by gaseous pollutants. Conclusions In large population-based cohorts exposed to low levels of air pollution with extended follow-up we observed associations between PM2.5 and non-accidental mortality for concentrations as low as 5 µg/m3.

Associations between fine particulate matter and mortality in the 2001 Canadian Census Health and Environment Cohort

Background Agricultural workers may be exposed to potential carcinogens including pesticides, sensitizing agents and solar radiation. Previous studies indicate increased risks of hematopoietic cancers and decreased risks at other sites, possibly due to differences in lifestyle or risk behaviours. We present findings from CanCHEC (Canadian Census Health and Environment Cohort), the largest national population-based cohort of agricultural workers. Methods Statistics Canada created the cohort using deterministic and probabilistic linkage of the 1991 Canadian Long Form Census to National Cancer Registry records for 1992–2010. Self-reported occupations were coded using the Standard Occupational Classification (1991) system. Analyses were restricted to employed persons aged 25–74 years at baseline (N = 2,051,315), with follow-up until December 31, 2010. Hazard ratios (HR) and 95% confidence intervals (CI) were modeled using Cox proportional hazards for all workers in agricultural occupations (n = 70,570; 70.8% male), stratified by sex, and adjusted for age at cohort entry, province of residence, and highest level of education. Results A total of 9515 incident cancer cases (7295 in males) occurred in agricultural workers. Among men, increased risks were observed for non-Hodgkin lymphoma (HR = 1.10, 95% CI = 1.00–1.21), prostate (HR = 1.11, 95% CI = 1.06–1.16), melanoma (HR = 1.15, 95% CI = 1.02–1.31), and lip cancer (HR = 2.14, 95% CI = 1.70–2.70). Decreased risks in males were observed for lung, larynx, and liver cancers. Among female agricultural workers there was an increased risk of pancreatic cancer (HR = 1.36, 95% CI = 1.07–1.72). Increased risks of melanoma (HR = 1.79, 95% CI = 1.17–2.73), leukemia (HR = 2.01, 95% CI = 1.24–3.25) and multiple myeloma (HR = 2.25, 95% CI = 1.16–4.37) were observed in a subset of female crop farmers. Conclusions Exposure to pesticides may have contributed to increased risks of hematopoietic cancers, while increased risks of lip cancer and melanoma may be attributed to sun exposure. The array of decreased risks suggests reduced smoking and alcohol consumption in this occupational group compared to the general population.

As there are no well‐established modifiable risk factors for prostate cancer, further evidence is needed on possible factors such as occupation. Our study uses one of the largest Canadian worker cohorts to examine occupation, industry, and prostate cancer and to assess patterns of prostate cancer rates. The Canadian Census Health and Environment Cohort (CanCHEC) was established by linking the 1991 Canadian Census Cohort to the Canadian Cancer Database (1969–2010), Canadian Mortality Database (1991–2011), and Tax Summary Files (1981–2011). A total of 37,695 prostate cancer cases were identified in men aged 25–74 based on age at diagnosis. Cox proportional hazards models were used to estimate hazards ratios and 95% confidence intervals. In men aged 25–74 years, elevated risks were observed in the following occupations: senior management (HR = 1.12, 95% CI: 1.04–1.20); office and administration (HR = 1.19, 95% CI: 1.11–1.27); finance services (HR = 1.09, 95% CI: 1.04–1.14); education (HR = 1.05, 95% CI: 1.00–1.11); agriculture and farm management (HR = 1.12, 95% CI: 1.06–1.17); farm work (HR = 1.11, 95% CI: 1.01–1.21); construction managers (HR = 1.07, 95% CI: 1.01–1.14); firefighting (HR = 1.17, 95% CI: 1.01–1.36); and police work (HR = 1.22, 95% CI: 1.09–1.36). Decreased risks were observed across other construction and transportation occupations. Results by industry were consistent with occupation results. Associations were identified for white‐collar, agriculture, protective services, construction, and transportation occupations. These findings emphasize the need for further study of job‐related exposures and the potential influence of nonoccupational factors such as screening practices.

Background Agricultural workers may be exposed to potential carcinogens including pesticides, sensitizing agents and solar radiation. Previous studies indicate increased risks of hematopoietic cancers and decreased risks at other sites, possibly due to differences in lifestyle or risk behaviours. We present findings from CanCHEC (Canadian Census Health and Environment Cohort), the largest national population-based cohort of agricultural workers. Methods Statistics Canada created the cohort using deterministic and probabilistic linkage of the 1991 Canadian Long Form Census to National Cancer Registry records for 1992–2010. Self-reported occupations were coded using the Standard Occupational Classification (1991) system. Analyses were restricted to employed persons aged 25–74 years at baseline (N = 2,051,315), with follow-up until December 31, 2010. Hazard ratios (HR) and 95% confidence intervals (CI) were modeled using Cox proportional hazards for all workers in agricultural occupations (n = 70,570; 70.8% male), stratified by sex, and adjusted for age at cohort entry, province of residence, and highest level of education. Results A total of 9515 incident cancer cases (7295 in males) occurred in agricultural workers. Among men, increased risks were observed for non-Hodgkin lymphoma (HR = 1.10, 95% CI = 1.00–1.21), prostate (HR = 1.11, 95% CI = 1.06–1.16), melanoma (HR = 1.15, 95% CI = 1.02–1.31), and lip cancer (HR = 2.14, 95% CI = 1.70–2.70). Decreased risks in males were observed for lung, larynx, and liver cancers. Among female agricultural workers there was an increased risk of pancreatic cancer (HR = 1.36, 95% CI = 1.07–1.72). Increased risks of melanoma (HR = 1.79, 95% CI = 1.17–2.73), leukemia (HR = 2.01, 95% CI = 1.24–3.25) and multiple myeloma (HR = 2.25, 95% CI = 1.16–4.37) were observed in a subset of female crop farmers. Conclusions Exposure to pesticides may have contributed to increased risks of hematopoietic cancers, while increased risks of lip cancer and melanoma may be attributed to sun exposure. The array of decreased risks suggests reduced smoking and alcohol consumption in this occupational group compared to the general population.

BackgroundAgricultural workers may be exposed to potential carcinogens including pesticides, sensitizing agents and solar radiation. Previous studies indicate increased risks of hematopoietic cancers and decreased risks at other sites, possibly due to differences in lifestyle or risk behaviours. We present findings from CanCHEC (Canadian Census Health and Environment Cohort), the largest national population-based cohort of agricultural workers.MethodsStatistics Canada created the cohort using deterministic and probabilistic linkage of the 1991 Canadian Long Form Census to National Cancer Registry records for 1992–2010. Self-reported occupations were coded using the Standard Occupational Classification (1991) system. Analyses were restricted to employed persons aged 25–74 years at baseline (N = 2,051,315), with follow-up until December 31, 2010. Hazard ratios (HR) and 95% confidence intervals (CI) were modeled using Cox proportional hazards for all workers in agricultural occupations (n = 70,570; 70.8% male), stratified by sex, and adjusted for age at cohort entry, province of residence, and highest level of education.ResultsA total of 9515 incident cancer cases (7295 in males) occurred in agricultural workers. Among men, increased risks were observed for non-Hodgkin lymphoma (HR = 1.10, 95% CI = 1.00–1.21), prostate (HR = 1.11, 95% CI = 1.06–1.16), melanoma (HR = 1.15, 95% CI = 1.02–1.31), and lip cancer (HR = 2.14, 95% CI = 1.70–2.70). Decreased risks in males were observed for lung, larynx, and liver cancers. Among female agricultural workers there was an increased risk of pancreatic cancer (HR = 1.36, 95% CI = 1.07–1.72). Increased risks of melanoma (HR = 1.79, 95% CI = 1.17–2.73), leukemia (HR = 2.01, 95% CI = 1.24–3.25) and multiple myeloma (HR = 2.25, 95% CI = 1.16–4.37) were observed in a subset of female crop farmers.ConclusionsExposure to pesticides may have contributed to increased risks of hematopoietic cancers, while increased risks of lip cancer and melanoma may be attributed to sun exposure. The array of decreased risks suggests reduced smoking and alcohol consumption in this occupational group compared to the general population.

The effectiveness of regulatory actions designed to improve air quality is often assessed by predicting changes in public health resulting from their implementation. Risk of premature mortality from long-term exposure to ambient air pollution is the single most important contributor to such assessments and is estimated from observational studies generally assuming a log-linear, no-threshold association between ambient concentrations and death. There has been only limited assessment of this assumption in part because of a lack of methods to estimate the shape of the exposure-response function in very large study populations. In this paper, we propose a new class of variable coefficient risk functions capable of capturing a variety of potentially non-linear associations which are suitable for health impact assessment. We construct the class by defining transformations of concentration as the product of either a linear or log-linear function of concentration multiplied by a logistic weighting function. These risk functions can be estimated using hazard regression survival models with currently available computer software and can accommodate large population-based cohorts which are increasingly being used for this purpose. We illustrate our modeling approach with two large cohort studies of long-term concentrations of ambient air pollution and mortality: the American Cancer Society Cancer Prevention Study II (CPS II) cohort and the Canadian Census Health and Environment Cohort (CanCHEC). We then estimate the number of deaths attributable to changes in fine particulate matter concentrations over the 2000 to 2010 time period in both Canada and the USA using both linear and non-linear hazard function models.Electronic supplementary materialThe online version of this article (doi:10.1007/s11869-016-0398-z) contains supplementary material, which is available to authorized users.

Background: There is evidence that local traffic density and living near major roads can adversely affect health outcomes. We aimed to assess the relationship between local road length, proximity to primary highways, and cause-specific mortality in the 1991 Canadian Census Health and Environment Cohort (CanCHEC).Methods: In this long-term study of 2.6 million people, based on completion of the long-form Census in 1991 and followed up until 2011, we used annual residential addresses to determine the total length of local roads within 200 m of centroid of postal codes, and the subject's distance to primary highways. The association between exposure to traffic and cause-specific mortality was estimated using Cox proportional hazards models, adjusting for individual covariates and contextual factors, including census division-level proportion in high school, the percentage of recent immigrants, and neighborhood income. We performed sensitivity analyses, including adjustment for exposure to PM2.5, restricted to subjects in core urban areas, and spatial variation by climatic zone.Results The hazard ratio (HR) for all non-accidental mortality associated with an interquartile increase in length of local roads was 1.05 (95% CI 1.04, 1.05); and for an interquartile range increase in proximity to primary highways, 1.03 (95% CI 1.02, 1.04). However, HRs by traffic quartile increased with increasing lengths of local roads, or closer proximity to primary highways, for all mortality causes. The associations were stronger in subject residing in urban core areas, attenuated by adjustment for PM2.5, and HRs showed limited spatial variation by climatic zone.Conclusion: In the CanCHEC cohort, exposure to greater road density and proximity to major traffic roads were associated with increased mortality risk from cerebrovascular and cardiovascular disease, ischemic heart disease, COPD, respiratory disease, lung cancer, and with unclear results for diabetes.

Oxidative burden of fine particulate air pollution and risk of cause-specific mortality in the Canadian Census Health and Environment Cohort (CanCHEC)

Previous studies often focus on individual air pollutants rather than their mixtures or specific sources. To assess associations between mixtures of fine particulate matter (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) from various industrial and residential sources and mortality from ischemic heart disease (IHD), cardiovascular disease (CVD), and non-accidental causes. The 2006 Canadian Census Health and Environment Cohort (CanCHEC) was linked to the Canadian Vital Statistics Database included 3,019,125 adults with 36,112,640 person-years of follow-up. Between 2006 and 2019, 56,190 IHD, 98,185 CVD, and 381,050 non-accidental deaths were identified. Annual concentrations of PM2.5, SO2, NO2, and O3 from upstream and downstream petroleum, non-ferrous smelting, the chemical industry, and residential fuel combustion were estimated by GEM-MACH model and assigned to participants' residential postal codes. Quantile g-computation estimated hazard ratios (HRs) per quartile increase in pollutant mixtures. We observed significant associations of IHD, CVD, and non-accidental mortality with the mixtures of air pollutants emitted from upstream petroleum [HR: 1.18 (95% CI: 1.12-1.24), 1.12 (1.08-1.16), and 1.05 (1.04-1.05)], downstream petroleum [1.06 (1.05-1.08), 1.04 (1.03-1.05), and 1.03 (1.02-1.03)], chemical industry [1.10 (1.08-1.13), 1.07 (1.06-1.09), and 1.10 (1.08-1.13)], and residential fuel combustion [1.18 (1.12-1.23), 1.12 (1.08-1.16), and 1.07 (1.05-1.09)]. PM2.5 and SO2 contributed most to increased mortality risks, while non-ferrous smelting emissions showed no association with CVD and non-accidental causes. PM2.5 and SO2 from certain sectors, but not all, greatly contribute to the increased risk of non-accidental, IHD, and CVD deaths.

Associations between long-term PM2.5 and ozone exposure and mortality in the Canadian Census Health and Environment Cohort (CANCHEC), by spatial synoptic classification zone

ObjectivesThe objective of this study was to compare occupational variation of the risk of bladder cancer in the Nordic countries and Canada.MethodsIn the Nordic Occupational Cancer study (NOCCA), 73 653...