Traffic-Related Air Pollution and Carotid Plaque Burden in a Canadian City With Low-Level Ambient Pollution.

Background The association between fine particulate matter and cardiovascular disease has been convincingly demonstrated. The role of traffic-related air pollutants is less clear. To better understand the role of traffic-related air pollutants in cardiovascular disease development, we examined associations between NO2, carotid atherosclerotic plaque, and cardiometabolic disorders associated with cardiovascular disease. Methods and Results Cross-sectional analyses were conducted among 2227 patients (62.9±13.8 years; 49.5% women) from the Stroke Prevention and Atherosclerosis Research Centre (SPARC) in London, Ontario, Canada. Total carotid plaque area measured by ultrasound, cardiometabolic disorders, and residential locations were provided by SPARC medical records. Long-term outdoor residential NO2 concentrations were generated by a land use regression model. Associations between NO2, total carotid plaque area, and cardiometabolic disorders were examined using multiple regression models adjusted for age, sex, smoking, and socioeconomic status. Mean NO2 was 5.4±1.6 ppb in London, Ontario. NO2 was associated with a significant increase in plaque (3.4 mm2 total carotid plaque area per 1 ppb NO2), exhibiting a linear dose-response. NO2 was also positively associated with triglycerides, total cholesterol, and the ratio of low- to high-density lipoprotein cholesterol (P<0.05). Diabetes mellitus mediated the relationship between NO2 and total carotid plaque area (P<0.05). Conclusions Our results demonstrate that even low levels of traffic-related air pollutants are linked to atherosclerotic plaque burden, an association that may be partially attributable to pollution-induced diabetes mellitus. Our findings suggest that reducing ambient concentrations in cities with NO2 below current standards would result in additional health benefits. Given the billions of people exposed to traffic emissions, our study supports the global public health significance of reducing air pollution.

Gallstone Ileus: Uncommon Presentation Followed by Less Common Spontaneous Resolution.

Gallstone ileus is a rare but significant cause of bowel obstruction. An 82-year-old female was admitted to the hospital with abdominal pain and was initially treated for a possible urinary tract infection. Following a surgical review and based on history, clinical examination as well as radiological findings, a diagnosis of gallstone ileus was made. The patient was prepared for surgery; however, whilst awaiting theatre, she spontaneously passed the obstructing gallstone with full resolution of bowel obstruction symptoms. The usual treatment for gallstone ileus is surgical management with an enterolithotomy; nevertheless, this case highlights the importance of close monitoring and adapting a management plan to fit an evolving clinical scenario.

Surveillance of cancer risks for firefighters, police, and armed forces among men in a Canadian census cohort.

BACKGROUND: Firefighters, police, and armed services may be exposed to hazards such as combustion by-products and shift work. METHODS: The CanCHEC cohort linked 1991 census data to the Canadian cancer registry for follow up. Cox proportional hazards modeling was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) to estimate risks for firefighter, police, or armed forces compared to workers in other occupations. RESULTS: The cohort of 1 108 410 men included 4535 firefighters, 10 055 police, and 9165 armed forces. For firefighters, elevated risks were noted for Hodgkin's lymphoma (HR: 2.89, 95%CI: 1.29-6.46), melanoma (HR: 1.67, 95%CI: 1.17-2.37), and prostate cancer (HR: 1.18, 95%CI: 1.01-1.37). Police had elevated risks for melanoma (HR:1.69, 95%CI: 1.32-2.16) and prostate cancer (HR:1.28, 95%CI: 1.14-1.42). No significant associations were found for armed forces workers. CONCLUSIONS: Canadian firefighters, police, and armed services, may be at an increased risk of developing certain cancers. Results suggested that a healthy worker effect may influence risk estimates.

Prostate cancer surveillance by occupation and industry: the Canadian Census Health and Environment Cohort (CanCHEC).

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.

Cancer Risks among Welders and Occasional Welders in a National Population-Based Cohort Study: Canadian Census Health and Environmental Cohort.

BACKGROUND: Welders are exposed to many known and suspected carcinogens. An excess lung cancer risk among welders is well established, but whether this is attributable to welding fumes is unclear. Excess risks of other cancers have been suggested, but not established. We investigated welding cancer risks in the population-based Canadian Census Health and Environmental Cohort. METHODS: Among 1.1 million male workers, 12,845 welders were identified using Standard Occupational Classification codes and followed through retrospective linkage of 1991 Canadian Long Form Census and Canadian Cancer Registry (1992-2010) records. Hazard ratios (HRs) were calculated using Cox proportional hazards models based on estimated risks of lung cancer, mesothelioma, and nasal, brain, stomach, kidney, and bladder cancers, and ocular melanoma. Lung cancer histological subtypes and risks by industry group and for occasional welders were examined. Some analyses restricted comparisons to blue-collar workers to minimize effects of potential confounders. RESULTS: Among welders, elevated risks were observed for lung cancer [HR: 1.16, 95% confidence interval (CI): 1.03-1.31], mesothelioma (HR: 1.78, 95% CI: 1.01-3.18), bladder cancer (HR: 1.40, 95% CI: 1.15-1.70), and kidney cancer (HR: 1.30, 95% CI: 1.01-1.67). When restricted to blue-collar workers, lung cancer and mesothelioma risks were attenuated, while bladder and kidney cancer risks increased. CONCLUSION: Excess risks of lung cancer and mesothelioma may be partly attributable to factors including smoking and asbestos. Welding-specific exposures may increase bladder and kidney cancer risks, and particular sources of exposure should be investigated. Studies that are able to disentangle welding effects from smoking and asbestos exposure are needed.

Occupational variation in incidence of bladder cancer: a comparison of population-representative cohorts from Nordic countries and Canada.

OBJECTIVES: The objective of this study was to compare occupational variation of the risk of bladder cancer in the Nordic countries and Canada. METHODS: In the Nordic Occupational Cancer study (NOCCA), 73 653 bladder cancer cases were observed during follow-up of 141.6 million person-years. In the Canadian Census Health and Environment Cohort (CanCHEC), 8170 cases were observed during the follow-up of 36.7 million person-years. Standardised incidence ratios with 95% CI were estimated for 53 occupations in the NOCCA cohort and HR with 95% CIs were estimated for 42 occupations in the CanCHEC. RESULTS: Elevated risks of bladder cancer were observed among hairdressers, printers, sales workers, plumbers, painters, miners and laundry workers. Teachers and agricultural workers had reduced risk of bladder cancer in both cohorts. Chimney-sweeps, tobacco workers and waiters had about 1.5-fold risk in the Nordic countries; no risk estimates for these categories were given from the CanCHEC cohort. CONCLUSION: We observed different occupational patterns in risk of bladder cancer in Nordic countries and Canada. The only occupation with similarly increased risk was observed among sales workers. Differences in smoking across occupational groups may explain some, but not all, of this variation.

Sedentary work and the risks of colon and rectal cancer by anatomical sub-site in the Canadian census health and environment cohort (CanCHEC).

BACKGROUND: Sedentary behaviour is a potential risk factor for colorectal cancer. We examined the association between sedentary work, based on body position, and colorectal cancer risk in Canadians. METHODS: A working body position category (a. sitting; b. standing and walking; c. sitting, standing, and walking; d. other) was assigned to occupations reported by 1991 Canadian Census respondents based on national occupational counselling guidelines. Adjusted hazard ratios (HRs) and 95% confidence intervals (CI) were estimated for cancers of the colon (overall, proximal, and distal) and rectum in men and women newly diagnosed from 1992 to 2010. RESULTS: Compared to "sitting" jobs, men in occupations with "other" (non-sitting, -standing, or -walking) body positions had a weakly significant reduced colon cancer risk (HR=0.93, 95% CI: 0.89, 0.98) primarily attributed to protection at the distal site (HR=0.90, 95% CI: 0.84, 0.97). Men in "standing and walking" and "sitting, standing, and walking" jobs did not have significantly reduced colon cancer risks. No effects were observed for rectal cancer in men or colon and rectal cancer in women. CONCLUSION: The two significant findings of this analysis should be followed-up in further investigations with additional information on potential confounders. Null findings for rectal cancer were consistent with other studies.

Cancer risks in a population-based study of 70,570 agricultural workers: results from the Canadian census health and Environment cohort (CanCHEC).

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.

The influence of community well-being on mortality among Registered First Nations people.

BACKGROUND: Living in a community with lower socioeconomic status is associated with higher mortality. However, few studies have examined associations between community socioeconomic characteristics and mortality among the First Nations population. DATA AND METHODS: The 1991-to-2006 Census Mortality and Cancer Cohort follow-up, which tracked a 15% sample of Canadians aged 25 or older, included 57,300 respondents who self-identified as Registered First Nations people or Indian band members. The Community Well-Being Index (CWB), a measure of the social and economic well-being of communities, consists of income, education, labour force participation, and housing components. A dichotomous variable was used to indicate residence in a community with a CWB score above or below the average for First Nations communities. Age-standardized mortality rates (ASMRs) were calculated for First Nations cohort members in communities with CWB scores above and below the First Nations average. Cox proportional hazards models examined the impact of CWB when controlling for individual characteristics. RESULTS: The ASMR for First Nations cohort members in communities with a below-average CWB was 1,057 per 100,000 person-years at risk, compared with 912 for those in communities with an above-average CWB score. For men, living in a community with below-average income and labour force participation CWB scores was associated with an increased hazard of death, even when individual socioeconomic characteristics were taken into account. Women in communities with below-average income scores had an increased hazard of death. INTERPRETATION: First Nations people in communities with below-average CWB scores tended to have higher mortality rates. For some components of the CWB, effects remained even when individual socioeconomic characteristics were taken into account.

Maternal and community predictors of gastroschisis and congenital diaphragmatic hernia in Canada.

PURPOSE: The incidence of gastroschisis (GS) has increased globally. Maternal age and smoking are risk factors and aboriginal communities may be more commonly affected. Factors leading to this increased incidence are otherwise unclear. We investigate maternal sociodemography, air pollution and personal risk factors comparing mothers of infants with GS with a control group of infants with diaphragmatic hernia (CDH) in a large population-based analysis. METHODS: Data were collected from a national, disease-specific pediatric surgical database (May 2006-June 2013). Maternal community sociodemographic information was derived from the Canadian 2006 Census. Univariate and multivariable analyses were performed examining maternal factors related to diagnosis of GS. RESULTS: GS infants come from poorer, less educated communities with more unemployment, less pollution, fewer immigrants, and more aboriginal peoples than infants with CDH. Teen maternal age, smoking, and illicit drug use, are associated with GS. CONCLUSION: Mothers of infants with GS are younger, more likely to smoke and come from socially disadvantaged communities with higher proportions of aboriginal peoples but lower levels of air pollution compared to mothers of CDH infants. Identification of maternal risks provides direction for prenatal screening and public health interventions.

Prostate cancer and occupational exposure to whole-body vibration in a national population-based cohort study.

BACKGROUND: Following preliminary evidence from observational studies, we test the potential relationship between whole-body vibration (WBV) and prostate cancer in a cohort study. METHODS: WBV exposure was assigned based on occupation in 1991 and 1,107,700 participants were followed for incident prostate cancer until the end of 2003. Adjusted hazard rate ratios (HRs) were calculated using Cox proportional hazards modeling. RESULTS: 17,922 incident prostate cancer cases were observed. WBV-exposed men in Natural and Applied Sciences Occupations had a 37% elevated risk of prostate cancer (95% CI 1.09-1.72) and WBV-exposed men in Trades, Transport, and Equipment Operators Occupations had a 9% reduced risk (95% CI 0.86-0.97). Independent of WBV exposure, small but significant differences in risk were seen for several occupational categories. CONCLUSIONS: We found no consistent relationship between WBV and prostate cancer. Further research could focus on other exposures or specific occupations in the studied categories to determine what may be contributing to the observed differences in prostate cancer risk.

An age- and cause decomposition of differences in life expectancy between residents of Inuit Nunangat and residents of the rest of Canada, 1989 to 2008.

BACKGROUND: This study quantifies differences in life expectancy between residents of Inuit Nunangat and people in the rest of Canada; estimates the contribution of specific causes of death to the differences; and examines these differences over time, by sex and by age group. DATA AND METHODS: A geographic approach was used to decompose differences in life expectancy for residents of Inuit Nunangat, compared with people living outside this geographic area. Differences in life expectancy by cause, sex, and age group were calculated using the discrete method of decomposition and were applied to abridged life tables. Causes of death were classified according to Global Burden of Disease categories. Attributable causes of death were calculated for causes amenable to medical intervention and for smoking-related diseases. RESULTS: The largest contributor to life expectancy differences between males in Inuit Nunangat and the rest of Canada was injury, particularly self-inflicted injury at ages 15 to 24. For females, the largest contributors were malignant neoplasm and respiratory disease at ages 65 to 79. INTERPRETATION: The gap in life expectancy between residents of Inuit Nunangat and the rest of Canada can be attributed to specific groups of causes occurring within specific age ranges.

Data resource profile: 1991 Canadian Census Cohort.

The 1991 Canadian Census Cohort is the largest population-based cohort in Canada (N=2,734,835). Prior to the creation of this Cohort, no national population-based Canadian cohort was available to examine mortality by socioeconomic indicators. The 1991 Canadian Census Cohort was created via the linkage of a sub-sample of respondents from the mandatory 1991 Canadian Census long-form to historical tax summary files, Canadian Mortality Database, Canadian Cancer Database, 1991 Health and Activity Limitation Survey and a sub-sample of the Longitudinal Worker File. Overall ascertainment of mortality and cancer is anticipated to be nearly complete and the Cohort is broadly representative of most groups in the Canadian population. The Cohort has been used to examine mortality outcomes by different indicators of socioeconomic status, occupational categories, ethnic groups, educational attainment, and for exposure to ambient air pollution. Results have shown that the estimated remaining years of life at age 25 differed substantially by income adequacy quintile, educational attainment, housing type and Aboriginal ancestry.

Causes and contributions to differences in life expectancy for Inuit Nunangat and Canada, 1994-2003.

OBJECTIVES: The objective of this article is to measure the contributions of age groups and causes of death to differences in mortality and life expectancy between residents of Inuit Nunangat and the rest of Canada. STUDY DESIGN: The geographic area of coverage includes communities within Inuit Nunangat, with the addition of Inuvik in the Northwest Territories. Deaths were compiled for 2 5-year periods, 1994 through 1998 and 1999 through 2003, with the mid-year centred on the 1996 and 2001 censuses. METHODS: Abridged life tables were constructed according to the revised Chiang method. Age decomposition of differences in life expectancy and cause-deleted life tables were calculated using a discrete approach. The age groups and causes contributing to differences in life expectancy between Inuit Nunangat and the rest of Canada were calculated. RESULTS: Specific age groups contribute more to the difference in life expectancy between Inuit Nunangat and the rest of Canada. For males, over 50% of the difference in life expectancy is due to excess mortality before 25 years of age, while for females nearly 65% is due to excess mortality after the age of 60. CONCLUSIONS: Cancer is a major contributor to the difference in life expectancy between residents of Inuit Nunangat and the rest of Canada; reduction in cancer rates would make the greatest contribution to gains in life expectancy. There are clear gender differences in life expectancy and mortality, with the total effect of mortality being greatest for males between 15 and 25 years of age and for females over the age of 60.