Volatile organic compounds (VOCs) in indoor air and tap water samples in residences of pregnant women living in an area of unconventional natural gas operations: Findings from the EXPERIVA study

BACKGROUND

Northeastern British Columbia (Canada) is an area of unconventional natural gas (UNG) exploitation by hydraulic fracturing, which can release several contaminants, including volatile organic compounds (VOCs). To evaluate gestational exposure to contaminants in this region, we undertook the Exposures in the Peace River Valley (EXPERIVA) study.

OBJECTIVES

We aimed to: 1) measure VOCs in residential indoor air and tap water from EXPERIVA participants; 2) compare concentrations with those in the general population and explore differences related to sociodemographic and housing characteristics; and 3) determine associations between VOC concentrations and density/proximity to UNG wells.

METHODS

Eighty-five pregnant women participated. Passive air samplers were analyzed for 47 VOCs, and tap water samples were analyzed for 44 VOCs. VOC concentrations were compared with those from the Canadian Health Measure Survey (CHMS). We assessed the association between different metrics of well density/proximity and indoor air and tap water VOC concentrations using multiple linear regression.

RESULTS

40 VOCs were detected in >50% of air samples, whereas only 4 VOCs were detected in >50% of water samples. We observed indoor air concentrations >95th percentile of CHMS in 10-60% of samples for several compounds (acetone, 2-methyl-2-propanol, chloroform, 1,4-dioxane, hexanal, m/p-xylene, o-xylene, styrene, decamethylcyclopentasiloxane, dodecane and decanal). Indoor air levels of chloroform and tap water levels of total trihalomethanes were higher in Indigenous participants compared to non-Indigenous participants. Indoor air levels of chloroform and acetone, and tap water levels of total trihalomethanes were positively associated with UNG wells density/proximity metrics. Indoor air BTEX (benzene, toluene, ethylbenzene, xylenes) levels were positively correlated with some well density/proximity metrics.

CONCLUSION

Our results suggest higher exposure to certain VOCs in pregnant women living in an area of intense unconventional natural gas exploitation compared with the general Canadian population, and that well density/proximity is associated with increased exposure to certain VOCs.

Air Pollution as a Risk Factor for Incident Chronic Obstructive Pulmonary Disease and Asthma. A 15-Year Population-based Cohort Study

Rationale: Current evidence on the relationship between long-term exposure to air pollution and new onset of chronic lung disease is inconclusive.Objectives: To examine associations of incident chronic obstructive pulmonary disease (COPD) and adult-onset asthma with past exposure to fine particulate matter ≤ 2.5 μm in diameter (PM_2.5), nitrogen dioxide (NO₂), ozone (O₃), and the redox-weighted average of NO₂ and O₃ (O_x) and characterize the concentration-response relationship.Methods: We conducted a population-based cohort study of all Ontarians, aged 35-85 years, from 2001 to 2015. A 3-year moving average of residential exposures to selected pollutants with a 1-year lag were estimated during follow-up. We used Cox proportional hazard models and Aalen additive-hazard models to quantify the pollution-disease associations and characterized the shape of these relationships using newly developed nonlinear risk models.Measurements and Main Results: Among 5.1 million adults, we identified 340,733 and 218,005 incident cases of COPD and asthma, respectively. We found positive associations of COPD with PM_2.5 per interquartile-range (IQR) increase of 3.4 μg/m³ (hazard ratio, 1.07; 95% confidence interval, 1.06-1.08), NO₂ per IQR increase of 13.9 ppb (1.04; 1.02-1.05), O₃ per IQR increase of 6.3 ppb (1.04; 1.03-1.04), and O_x per IQR increase of 4.4 ppb (1.03; 1.03-1.03). By contrast, we did not find strong evidence linking these pollutants to adult-onset asthma. In addition, we quantified that each IQR increase in pollution exposure yielded 3.0 (2.4-3.6), 3.2 (2.0-4.3), 1.9 (1.3-2.5), and 2.3 (1.7-2.9) excess cases of COPD per 100,000 adults for PM_2.5, NO₂, O₃, and O_x, respectively. Furthermore, most pollutant-COPD relationships exhibited supralinear shapes.Conclusions: Air pollution was associated with a higher incidence of COPD but was not associated with a higher incidence of adult-onset asthma.

Long-term exposure to iron and copper in fine particulate air pollution and their combined impact on reactive oxygen species concentration in lung fluid: a population-based cohort study of cardiovascular disease incidence and mortality in Toronto, Canada

BACKGROUND

Exposure to fine particulate (PM2.5) air pollution is associated with increased cardiovascular disease (CVD), but less is known about its specific components, such as metals originating from non-tailpipe emissions. We investigated the associations of long-term exposure to metal components [iron (Fe) and copper (Cu)] in PM2.5 with CVD incidence.

METHODS

We conducted a population-based cohort study in Toronto, Canada. Exposures to Fe and Cu in PM2.5 and their combined impact on the concentration of reactive oxygen species (ROS) in lung fluid were estimated using land use regression models. Incidence of acute myocardial infarction (AMI), congestive heart failure (CHF) and CVD death was ascertained using health administrative datasets. We used mixed-effects Cox regression models to examine the associations between the exposures and health outcomes. A series of sensitivity analyses were conducted, including indirect adjustment for individual-level cardiovascular risk factors (e.g. smoking), and adjustment for PM2.5 and nitrogen dioxide (NO2).

RESULTS

In single-pollutant models, we found positive associations between the three exposures and all three outcomes, with the strongest associations detected for the estimated ROS. The associations of AMI and CHF were sensitive to indirect adjustment, but remained robust for CVD death in all sensitivity analyses. In multi-pollutant models, the associations of the three exposures generally remained unaltered. Interestingly, adjustment for ROS did not substantially change the associations between PM2.5 and CVD, but attenuated the associations of NO2.

CONCLUSIONS

Long-term exposure to Fe and Cu in PM2.5 and their combined impact on ROS were consistently associated with increased CVD death.

A Population-Based Cohort Study of Respiratory Disease and Long-Term Exposure to Iron and Copper in Fine Particulate Air Pollution and Their Combined Impact on Reactive Oxygen Species Generation in Human Lungs

Metal components in fine particulate matter (PM_2.5) from nontailpipe emissions may play an important role in underlying the adverse respiratory effects of PM_2.5. We investigated the associations between long-term exposure to iron (Fe) and copper (Cu) in PM_2.5 and their combined impact on reactive oxygen species (ROS) generation in human lungs, and the incidence of asthma, chronic obstructive pulmonary disease (COPD), COPD mortality, pneumonia mortality, and respiratory mortality. We conducted a population-based cohort study of ∼0.8 million adults in Toronto, Canada. Land-use regression models were used to estimate the concentrations of Fe, Cu, and ROS. Outcomes were ascertained using validated health administrative databases. We found positive associations between long-term exposure to Fe, Cu, and ROS and the risks of all five respiratory outcomes. The associations were more robust for COPD, pneumonia mortality, and respiratory mortality than for asthma incidence and COPD mortality. Stronger associations were observed for ROS than for either Fe or Cu. In two-pollutant models, adjustment for nitrogen dioxide somewhat attenuated the associations while adjustment for PM_2.5 had little influence. Long-term exposure to Fe and Cu in PM_2.5 and estimated ROS concentration in lung fluid was associated with increased incidence of respiratory diseases, suggesting the adverse respiratory effects of nontailpipe emissions.

Exposure to Road Traffic Noise and Incidence of Acute Myocardial Infarction and Congestive Heart Failure: A Population-Based Cohort Study in Toronto, Canada

BACKGROUND

Epidemiological evidence for the association between traffic-related noise and the incidence of major cardiovascular events such as acute myocardial infarction (AMI) and congestive heart failure (CHF) is inconclusive, especially in North America.

OBJECTIVES

We evaluated the associations between long-term exposure to road traffic noise and the incidence of AMI and CHF.

METHODS

Our study population comprised ∼1 million people 30-100 years of age who lived in Toronto, Canada, from 2001 to 2015 and were free of AMI (referred to as the AMI cohort) or CHF (the CHF cohort) at baseline. Outcomes were ascertained from health administrative databases using validated algorithms. Annual average noise levels were estimated as the A-weighted equivalent sound pressure level over the 24-h period (LAeq24) and during nighttime (LAeqNight), respectively, using propagation modeling, and assigned to participants' annual six-digit postal code addresses during follow-up. We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) for incident AMI and CHF in relation to LAeq24 and LAeqNight using random-effects Cox proportional hazards models adjusting for individual- and census tract-level covariates, including traffic-related air pollutants [e.g., ultrafine particles (UFPs) and nitrogen dioxide].

RESULTS

During follow-up, there were 37,441 AMI incident cases and 95,138 CHF incident cases. Each interquartile range change in LAeq24 was associated with an increased risk of incident AMI (HR=1.07; 95% CI: 1.06, 1.08) and CHF (HR=1.07; 95% CI: 1.06, 1.09). Similarly, LAeqNight was associated with incident AMI (HR=1.07; 95% CI: 1.05, 1.08) and CHF (HR=1.06; 95% CI: 1.05, 1.07). These results were robust to various sensitivity analyses and remained elevated after controlling for long-term exposure to UFPs and nitrogen dioxide. We found near-linear relationships between noise and the incidence of AMI and CHF with no evidence of threshold values.

CONCLUSION

In this large cohort study in Toronto, Canada, chronic exposure to road traffic noise was associated with elevated risks for AMI and CHF incidence. https://doi.org/10.1289/EHP5809.

Residential Greenness and Cardiovascular Disease Incidence, Readmission, and Mortality

BACKGROUND

Living in greener areas of cities was linked to increased physical activity levels, improved mental well-being, and lowered harmful environmental exposures, all of which may affect human health. However, whether living in greener areas may be associated with lower risk of cardiovascular disease incidence, progression, and premature mortality is unclear.

OBJECTIVES

We conducted a cohort study to examine the associations between residential green spaces and the incidence of acute myocardial infarction (AMI) and heart failure (HF), post-AMI and HF hospital readmissions, and mortality.

METHODS

We simultaneously followed four large population-based cohorts in Ontario, Canada, including the entire adult population, adults free of AMI and HF, and survivors of AMI or HF from 2000 to 2014. We estimated residential exposure to green spaces using satellite-derived observations and ascertained health outcomes using validated disease registries. We estimated the associations using spatial random-effects Cox proportional hazards models. We conducted various sensitivity analyses, including further adjusting for property values and performing exploratory mediation analysis.

RESULTS

Each interquartile range increase in residential greenness was associated with a 7% [95% confidence interval (CI): 4%, 9%] decrease in incident AMI and a 6% (95% CI: 4%, 7%) decrease in incident HF. Residential greenness was linked to a ∼10% decrease in cardiovascular mortality in both adults free of AMI and HF and the entire adult population. These associations remained consistent in sensitivity analyses and were accentuated among younger adults. Additionally, we estimated that the decreases in AMI and HF incidence associated with residential greenness explained ∼53% of the protective association between residential greenness and cardiovascular mortality. Conversely, residential greenness was not associated with any delay in readmission or mortality among AMI and HF patients.

CONCLUSIONS

Living in urban areas with more green spaces was associated with improved cardiovascular health in people free of AMI and HF but not among individuals who have already developed these conditions. https://doi.org/10.1289/EHP6161.

Urban green space and the risks of dementia and stroke

INTRODUCTION

It is unknown whether urban green space is associated with reduced risk of major neurological conditions, especially dementia and stroke.

METHODS

Retrospective, population-based cohorts were created for each study outcome, including 1.7 and 4.3 million adults in Ontario, Canada for dementia and stroke, respectively. Residential green space was quantified using the satellite-derived Normalized Difference Vegetation Index. Incidence was ascertained using health administrative data with validated algorithms. Mixed-effects Cox models were used to estimate hazard ratios per interquartile range increase in green space exposure.

RESULTS

Between 2001 and 2013, 219,013 individuals were diagnosed with dementia and 89,958 had a stroke. The hazard ratio per interquartile range increase in green space was 0.97 (95% CI: 0.96-0.98) for dementia and 0.96 (0.95-0.98) for stroke. Estimates remained generally consistent in sensitivity analyses.

DISCUSSION

Increased exposure to urban green space was associated with reduced incidence of dementia and stroke. To our knowledge, this is the first population-based cohort study to assess these relationships.

An approach to estimating the environmental burden of cancer from known and probable carcinogens: application to Ontario, Canada

BACKGROUND

Quantifying the potential cancer cases associated with environmental carcinogen exposure can help inform efforts to improve population health. This study developed an approach to estimate the environmental burden of cancer and applied it to Ontario, Canada. The purpose was to identify environmental carcinogens with the greatest impact on cancer burden to support evidence-based decision making.

METHODS

We conducted a probabilistic assessment of the environmental burden of cancer in Ontario. We selected 23 carcinogens that we defined as "environmental" (e.g., pollutants) and were relevant to the province, based on select classifications provided by the International Agency for Research on Cancer. We evaluated population exposure to the carcinogens through inhalation of indoor/outdoor air; ingestion of food, water, and dust; and exposure to radiation. We obtained or calculated concentration-response functions relating carcinogen exposure and the risk of developing cancer. Using both human health risk assessment and population attributable fraction models in a Monte Carlo simulation, we estimated the annual cancer cases associated with each environmental carcinogen, reporting the simulation summary (e.g., mean and percentiles).

RESULTS

We estimated between 3540 and 6510 annual cancer cases attributable to exposure to 23 environmental carcinogens in Ontario. Three carcinogens were responsible for over 90% of the environmental burden of cancer: solar ultraviolet (UV) radiation, radon in homes, and fine particulate matter (PM_2.5) in outdoor air. Eight other carcinogens had an estimated mean burden of at least 10 annual cancer cases: acrylamide, arsenic, asbestos, chromium, diesel engine exhaust particulate matter, dioxins, formaldehyde, and second-hand smoke. The remaining 12 carcinogens had an estimated mean burden of less than 10 annual cancer cases in Ontario.

CONCLUSIONS

We found the environmental burden of cancer in Ontario to fall between previously estimated burdens of alcohol and tobacco use. These results allow for a comparative assessment across carcinogens and offer insights into strategies to reduce the environmental burden of cancer. Our analysis could be adopted by other jurisdictions and repeated in the future for Ontario to track progress in reducing cancer burden, assess newly classified environmental carcinogens, and identify top burden contributors.

Association Between Road Traffic Noise and Incidence of Diabetes Mellitus and Hypertension in Toronto, Canada: A Population-Based Cohort Study

Background Exposure to road traffic noise has been linked to cardiometabolic complications, such as elevated blood pressure and glucose dysregulation. However, epidemiologic evidence linking road traffic noise to diabetes mellitus and hypertension remains scarce. We examined associations between road traffic noise and the incidence of diabetes mellitus and hypertension in Toronto, Canada. Methods and Results Using the Ontario Population Health and Environment Cohort, we conducted a retrospective, population-based cohort study of long-term residents of Toronto, aged 35 to 100 years, who were registered for provincial publicly funded health insurance, and were without a history of hypertension (n=701 174) or diabetes mellitus (n=914 607). Road traffic noise exposure levels were assessed by the equivalent continuous A-weighted sound pressure level (dBA) for the 24-hour day and the equivalent continuous A-weighted sound pressure level for the night (11 pm-7am). Noise exposures were assigned to subjects according to their annual residential postal codes during the 15-year follow-up. We used random-effect Cox proportional hazards models adjusting for personal and area-level characteristics. From 2001 to 2015, each interquartile range increase in the equivalent continuous A-weighted sound pressure level (dBA) for the 24-hour day (10.0 dBA) was associated with an 8% increase in incident diabetes mellitus (95% CI, 1.07-1.09) and a 2% increase in hypertension (95% CI, 1.01-1.03). We obtained similar estimates with the equivalent continuous A-weighted sound pressure level for the night (11 pm-7am). These results were robust to all sensitivity analyses conducted, including further adjusting for traffic-related air pollutants (ultrafine particles and nitrogen dioxide). For both hypertension and diabetes mellitus, we observed stronger associations with the equivalent continuous A-weighted sound pressure level (dBA) for the 24-hour day among women and younger adults (aged <60 years). Conclusions Long-term exposure to road traffic noise was associated with an increased incidence of diabetes mellitus and hypertension in Toronto.

Regional variations in human chemical exposures in Canada: A case study using biomonitoring data from the Canadian Health Measures Survey for the provinces of Quebec and Ontario

The Canadian Health Measures Survey (CHMS), an ongoing national health survey conducted in two-year cycles, collects extensive biomonitoring data that is used to assess the exposure of Canadians to environmental chemicals of concern. Combining data from multiple cycles of the CHMS allows for the calculation of robust regional estimates of chemical concentrations in blood and urine. The objective of this work was to compare biomarkers of exposure to several environmental chemicals for the provinces of Quebec and Ontario, two major CHMS regions, as well as the entire CHMS (representing Canada) minus Quebec (CMQ), and the entire CHMS minus Ontario (CMO), and to interpret differences between regions. Geometric means and 95th percentiles of blood and/or urinary concentrations of 45 environmental chemicals or their metabolites for Ontario, Quebec, CMQ, and CMO were calculated by combining the two most recent cycles of data available for a chemical (cycles 1 and 2, or cycles 2 and 3) from the first three cycles of the CHMS (2007-2013). Weighted one-way ANOVA was used to test the differences between regional estimates. After applying a Bonferonni-Holm adjustment for multiple comparisons, the following measures were significantly higher in Quebec as compared to Ontario and CMQ: blood lead, urinary lead and the urinary polyaromatic hydrocarbon (PAH) metabolites, 9-hydroxyfluorene, 1-hydroxyphenanthrene, 2- hydroxyphenanthrene and 3-hydroxyphenanthrene. In Quebec compared to CMQ only, urinary 2-hydroxfluorene, 3-hydroxyfluorene, 2-hydroxynaphthalene, and 4-hydroxyphenanthrene were higher. The concentration of urinary fluoride was significantly higher in Ontario as compared to Quebec and CMO. Blood manganese and urinary fluoride were significantly lower in Quebec compared to CMQ, and blood and urinary selenium were significantly lower in Ontario compared to CMO. Regional differences in tobacco use, age of dwellings and drinking water fluoridation are among the possible contributing factors to some of the observed differences. In conclusion, this is the first study where biomonitoring data from multiple cycles of CHMS were combined in order to generate robust estimates for subsets of the Canadian population. Such assessments can contribute to a regional-level prioritization of control measures to reduce the exposure of Canadians to chemicals in their environment.

The impact of air pollution on the incidence of diabetes and survival among prevalent diabetes cases

PURPOSE

Growing evidence implicates ambient air pollutants in the development of major chronic diseases and premature mortality. However, epidemiologic evidence linking air pollution to diabetes remains inconclusive. This study sought to determine the relationships between selected air pollutants (nitrogen dioxide [NO₂], fine particulate matter [PM_2.5], ozone [O₃], and oxidant capacity [Ox; the redox-weighted average of O₃ and NO₂]) and the incidence of diabetes, as well as the risk of cardiovascular or diabetes mortality among individuals with prevalent diabetes.

RESEARCH DESIGN AND METHODS

We followed two cohorts, which included 4.8 million Ontario adults free of diabetes and 452,590 Ontario adults with prevalent diabetes, from 2001 to 2015. Area-level air pollution exposures were assigned to subjects' residential areas, and outcomes were ascertained using health administrative data with validated algorithms. We estimated hazard ratios for the association between each air pollutant and outcome using Cox proportional hazards models, and modelled the shape of the concentration-response relationships.

RESULTS

Over the study period, 790,461 individuals were diagnosed with diabetes. Among those with prevalent diabetes, 26,653 died from diabetes and 64,773 died from cardiovascular diseases. For incident diabetes, each IQR increase in NO₂ had a hazard ratio of 1.04 (95% CI: 1.03-1.05). This relationship was relatively robust to all sensitivity analyses considered, and exhibited a near-linear shape. There were also positive associations between incident diabetes and PM_2.5, O₃, and Ox, but these estimates were somewhat sensitive to different models considered. Among those with prevalent diabetes, almost all pollutants were associated with increased diabetes and cardiovascular mortality risk. The strongest association was observed between diabetes mortality and exposure to NO₂ (HR = 1.08, 95% CI: 1.02-1.13).

CONCLUSIONS

Selected air pollutants, especially NO₂, were linked to an increased risk of incident diabetes, as well as risk of cardiovascular or diabetes mortality among persons with prevalent diabetes. As NO₂ is frequently used as a proxy for road traffic exposures, this result may indicate that traffic-related air pollution has the strongest effect on diabetes etiology and survival after diabetes development.

Evidence synthesis - Evaluating risk communication during extreme weather and climate change: a scoping review

INTRODUCTION

Communicating risk to the public continues to be a challenge for public health practitioners working in the area of climate change. We conducted a scoping literature review on the evaluation of risk communication for extreme weather and climate change to inform local public health messaging, consistent with requirements under the Ontario Public Health Standards (OPHS), which were updated in 2018 to include effective communication regarding climate change and extreme weather.

METHODS

Search strategies were developed by library information specialists and used to retrieve peer-reviewed academic and grey literature from bibliographic databases (Medline, Embase, Scopus and CINAHL) and Google country specific searches, respectively. The search strategy was validated through a workshop with experts and community stakeholders, with expertise in environment, health, emergency management and risk communication.

RESULTS

A total of 43 articles were included. These articles addressed issues such as: climate change (n = 22), flooding (n = 12), hurricane events (n = 5), extreme heat (n = 2), and wild fires (n = 2). Studies were predominantly from the US (n = 14), Europe (n = 6) and Canada (n = 5).

CONCLUSION

To meet the OPHS 2018, public health practitioners need to engage in effective risk communication to motivate local actions that mitigate the effects of extreme weather and climate change. Based on the scoping review, risk communication efforts during short-term extreme weather events appear to be more effective than efforts to communicate risk around climate change. This distinction could highlight a unique opportunity for public health to adapt strategies commonly used for extreme weather to climate change.

Is neighbourhood walkability related to body mass index among different age groups? A cross-sectional study of Canadian urban areas

BACKGROUND

Studies of neighbourhood walkability and body mass index (BMI) have shown mixed results, possibly due to biases from self-reported outcomes or differential effects across age groups. Our objective was to examine relationships between walkability and objectively measured BMI in various age groups, in a nationally representative population.

METHODS

The study population came from the 2007-2011 Canadian Health Measures Survey, a cross-sectional survey of a nationally representative Canadian population. In our covariate-adjusted analyses, we included survey respondents aged 6-79 who were not pregnant, did not live in rural areas, were not missing data and were not thin/underweight. We used objectively measured height and weight to calculate BMI among adults aged 18-79 and zBMI among children aged 6-17. We categorised respondents into walkability quintiles based on their residential Street Smart Walk Score values. We performed linear regression to estimate differences between walkability quintiles in BMI and zBMI. We analysed adults and children overall; age subgroups 6-11, 12-17, 18-29, 30-44, 45-64 and 65-79; and sex subgroups.

RESULTS

The covariate-adjusted models included 9265 respondents overall. After adjustment, differences between walkability quintiles in BMI and zBMI were small and not statistically significant, except for males aged 6-17 in the second-highest walkability quintile who had significantly lower zBMIs than those in the lowest quintile.

CONCLUSION

After accounting for confounding factors, we did not find evidence of a relationship between walkability and BMI in children or adults overall, or in any age subgroup with sexes combined. However, post hoc analysis by sex suggested males aged 6-17 in more walkable areas may have lower zBMIs.

Exposure to ambient air pollution and the incidence of congestive heart failure and acute myocardial infarction: A population-based study of 5.1 million Canadian adults living in Ontario

Long-term exposure to ambient air pollution has been linked to cardiovascular mortality, but the associations with incidence of major cardiovascular diseases are not fully understood, especially at low concentrations. We aimed to investigate the associations between exposure to fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), ozone (O₃), redox-weighted average of NO₂ and O₃ (O_x) and incidence of congestive heart failure (CHF) and acute myocardial infarction (AMI). Our study population included all long-term residents aged 35-85 years who lived in Ontario, Canada, from 2001 to 2015 (~5.1 million). Incidence of CHF and AMI were ascertained from validated registries. We assigned estimates of annual concentrations of pollutants to the residential postal codes of subjects for each year during follow-up. We estimated hazard ratios (HRs) and 95% CIs for each pollutant separately using Cox proportional hazards models. We examined the shape of concentration-response associations using shape-constrained health impact functions. From 2001 to 2015, there were 422,625 and 197,628 incident cases of CHF and AMI, respectively. In the fully adjusted analyses, the HRs of CHF corresponding to each interquartile range increase in exposure were 1.05 (95% CI: 1.04-1.05) for PM_2.5, 1.02 (95% CI: 1.01-1.04) for NO₂, 1.03 (95% CI: 1.02-1.03) for O₃, and 1.02 (95% CI: 1.02-1.03) for O_x, respectively. Similarly, exposure to PM_2.5, O₃, and O_x were positively associated with AMI. The concentration-response relationships were different for individual pollutant and outcome combinations (e.g., for PM_2.5 the relationship was supralinear with CHF, and linear with AMI).

Ambient Air Pollution and the Risk of Atrial Fibrillation and Stroke: A Population-Based Cohort Study

BACKGROUND

Although growing evidence links air pollution to stroke incidence, less is known about the effect of air pollution on atrial fibrillation (AF), an important risk factor for stroke.

OBJECTIVES

We assessed the associations between air pollution and incidence of AF and stroke. We also sought to characterize the shape of pollutant-disease relationships.

METHODS

The population-based cohort comprised 5,071,956 Ontario residents, age 35–85 y and without the diagnoses of both outcomes on 1 April 2001 and was followed up until 31 March 2015. AF and stroke cases were ascertained using health administrative databases with validated algorithms. Based on annual residential postal codes, we assigned 5-y running average concentrations of fine particulate matter ([Formula: see text]), nitrogen dioxide ([Formula: see text]), and ozone ([Formula: see text]) from satellite-derived data, a land-use regression model, and a fusion-based method, respectively, as well as redox-weighted averages of [Formula: see text] and [Formula: see text] ([Formula: see text]) for each year. Using Cox proportional hazards models, we estimated the hazard ratios (HRs) and 95% confidence intervals (95% CIs) of AF and stroke with each of these pollutants, adjusting for individual- and neighborhood-level variables. We used newly developed nonlinear risk models to characterize the shape of pollutant–disease relationships.

RESULTS

Between 2001 and 2015, we identified 313,157 incident cases of AF and 122,545 cases of stroke. Interquartile range increments of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] were associated with increases in the incidence of AF [HRs (95% CIs): 1.03 (1.01, 1.04), 1.02 (1.01, 1.03), 1.01 (1.00, 1.02), and 1.01 (1.01, 1.02), respectively] and the incidence of stroke [HRs (95% CIs): 1.05 (1.03, 1.07), 1.04 (1.01, 1.06), 1.05 (1.03, 1.06), and 1.05 (1.04, 1.06), respectively]. Associations of similar magnitude were found in various sensitivity analyses. Furthermore, we found a near-linear association for stroke with [Formula: see text], whereas [Formula: see text], [Formula: see text]-, and [Formula: see text] relationships exhibited sublinear shapes.

CONCLUSIONS

Air pollution was associated with stroke and AF onset, even at very low concentrations. https://doi.org/10.1289/EHP4883.

Exposure to ambient air pollution and the incidence of lung cancer and breast cancer in the Ontario Population Health and Environment Cohort

Lung and female breast cancers are highly prevalent worldwide. Although the association between exposure to ambient fine particulate matter (PM_2.5 ) and lung cancer has been recognized, there is less evidence for associations with other common air pollutants such as nitrogen dioxide (NO₂ ) and ozone (O₃ ). Even less is known about potential associations between these pollutants and breast cancer. We conducted a population-based cohort study to investigate the associations of chronic exposure to PM_2.5 , NO₂ , O₃ and redox-weighted average of NO₂ and O₃ (O_x ) with incident lung and breast cancer, using the Ontario Population Health and Environment Cohort (ONPHEC), which includes all long-term residents aged 35-85 years who lived in Ontario, Canada, 2001-2015. Incident lung and breast cancers were ascertained using the Ontario Cancer Registry. Annual estimates of exposures were assigned to the residential postal codes of subjects for each year during follow-up. We used Cox proportional-hazards models adjusting for personal- and neighborhood-level covariates. Our cohorts for lung and breast cancer analyses included ~4.9 million individuals and ~2.5 million women, respectively. During follow-up, 100,146 incident cases of lung cancer and 91,146 incident cases of breast cancer were diagnosed. The fully adjusted analyses showed positive associations of lung cancer incidence with PM_2.5 (hazard ratio [HR] = 1.02 [95% CI: 1.01-1.05] per 5.3 μg/m³ ) and NO₂ (HR = 1.05 [95% CI: 1.03-1.07] per 14 ppb). No associations with lung cancer were observed for O₃ or O_x . Relationships between PM_2.5 and NO₂ with lung cancer exhibited a sublinear shape. We did not find compelling evidence linking air pollution to breast cancer.

A systematic review of the health impacts of occupational exposure to wildland fires

The aim of the paper is to summarize the evidence of health impacts of occupational exposure to wildland fires. The authors searched 3 databases for relevant articles and screened the results. After full-text review, articles were included based on pre-determined criteria. The authors identified 32 relevant articles. Occupational exposure to wildland fires affects lung function in the short term and may increase the risk of hypertension in the long term. Exposure to wildland fires is also associated with post-traumatic stress symptoms. There was insufficient evidence to comment on most longer-term risks, and in particular on respiratory disease or cancer risks. Further research is required to understand whether occupational exposure to wildland fires results in clinically significant impacts on respiratory function, and to further clarify the relationship between occupational exposure and blood pressure, mental health, and cancer outcomes. Int J Occup Med Environ Health. 2019;32(2):121-40.

Total, methyl and inorganic mercury concentrations in blood and environmental exposure sources in newcomer women in Toronto, Canada

Measurements of total blood Hg (tHg), often used as a proxy for methyl Hg (MeHg) concentrations, are most commonly the focus of population-based studies. Data on Hg species in biomarkers can allow for a more nuanced characterization of environmental exposure sources and risk but their availability is limited, especially for newcomer populations. The purpose of the Metals in Newcomer Women (MNW) study was to address existing data gaps on metal concentrations and exposure sources in newcomer women (19-45 years) and to examine tHg, MeHg and inorganic Hg (iHg) in the blood of East and South Asian women recently arrived to Toronto. Study participants were recruited in 2015 (n = 211). Total Hg concentrations were determined using both ICP-Q-MS and isotope dilution (ID)-SPME-GC-ICP-MS. A sample subset (n = 76) was chosen for the analysis of blood MeHg and iHg concentrations (also using ID-SPME-GC-ICP-MS). Hierarchical regression models were used to assess associations between blood tHg concentrations and environmental exposure factors for MNW participants. For the sample subset, a log-linear model was used to examine associations between blood iHg and MeHg concentrations and fish consumption patterns. The geometric mean (GM) blood tHg concentration was 1.05 µg/L (95% CI: 0.88-1.25), which was elevated compared to Canadian-born women (GM: 0.57 µg/L; 95% CI: 0.49-0.66), in a specialized data analysis of the Canadian Health Measures Survey (CHMS). GM concentrations for iHg and MeHg were 0.21 µg/L (95% CI: 0.16-0.28) and 2.66 µg/L (95% CI: 2.00-3.55), respectively. Significant distal determinants associated with blood tHg concentrations were: level of educational attainment, having lived in a coastal/fishing community prior to arrival, and global region of origin. Use of iron supplements and consumption of higher mercury fish species were also associated with tHg concentrations in the fully adjusted model. The study results demonstrate that blood Hg concentrations in newcomer women are slightly elevated, with some individuals in exceedance of recommended concentrations for women of reproductive age. The consumption of fish species low in Hg is recommended for newcomer women, especially those who consume fish frequently.

Estimated Annual Deaths, Hospitalizations, and Emergency Department and Physician Office Visits from Foodborne Illness in Ontario

Public Health Ontario is working to estimate the burden of disease from environmental hazards in Ontario, Canada. As part of this effort, we estimated deaths and health care utilization resulting from exposure to pathogens and toxic substances in food. We applied fractions for the proportion of illness attributable to foodborne transmission to the annual (2008–2012) counts of deaths, hospitalizations, emergency department (ED) visits, and physician office visits for 15 diseases (13 pathogen-specific diseases and 2 nonspecific syndromes) captured by administrative health data. Nonspecific gastroenteritis (causative agent unknown) was the dominant disease, accounting for 98% of ED visits, 94% of hospitalizations, and 88% of deaths annually attributed to the 15 diseases. We estimated that foodborne nonspecific gastroenteritis results in ∼137,000 physician office visits (1000/100,000 population), 40,000 ED visits (310/100,000), 6200 hospitalizations (47/100,000), and 59 deaths (0.45/100,000) in Ontario per year (mean estimates). Our results indicate that pathogen-specific approaches to foodborne disease surveillance can substantially underestimate the deaths and illness resulting from exposure to foodborne pathogens and other causes of foodborne illness.

Long-term exposure to air pollution and the incidence of multiple sclerosis: A population-based cohort study

BACKGROUND

Evidence of the adverse neurological effects of exposure to ambient air pollution is emerging, but little is known about its effect on the development of multiple sclerosis (MS), the most common autoimmune disease of the central nervous system.

OBJECTIVES

To investigate the associations between MS incidence and long-term exposures to fine particles (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃) METHODS: We conducted a population-based cohort study to investigate the associations between long-term exposures to PM_2.5, NO₂, and O₃ and the incidence of MS. Our study population included all Canadian-born residents aged 20-40 years who lived in the province of Ontario, Canada from 2001 to 2013. Incident MS was ascertained from a validated registry. We assigned estimates of annual concentrations of these pollutants to the residential postal codes of subjects for each year during the 13 years of follow-up. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for each pollutant separately using random-effects Cox proportional hazards models. We conducted various sensitivity analyses, such as lagging exposure up to 5 years and adjusting for access to neurological care, annual average temperature, and population density.

RESULTS

Between 2001 and 2013, we identified 6203 incident cases of MS. The adjusted HR of incident MS was 0.96 (95% CI: 0.86-1.07) for PM_2.5, 0.91(95% CI: 0.81-1.02) for NO₂, and 1.09 (95% CI: 0.98-1.23) for O₃. These results were robust to various sensitivity analyses conducted.

CONCLUSIONS

In this large population-based cohort, we did not observe significant associations between MS incidence and long-term exposures to PM_2.5, NO₂, and O₃ in adults in Ontario, 2001-2013.

Environmental factors associated with blood lead among newcomer women from South and East Asia in the Greater Toronto Area

BACKGROUND

Newcomers bring with them histories of environmental exposure in their home countries and may have different sources of lead (Pb) exposure compared to other residents of their adopted country.

AIMS

To describe past and current factors associated with Pb exposure and blood Pb among South and East Asian newcomer women of reproductive age in the Greater Toronto Area (GTA), Ontario, Canada.

METHODS

In collaboration with public health units and community organizations a community-based research model was utilized by recruiting peer researchers to assist in all aspects of the study. Blood samples were taken and phone interviews were conducted. Canadian Health Measures Survey (CHMS) cycles 1, 2, and 3 data was used to contextualize the distribution blood Pb levels. Multiple regression was applied to log-transformed blood lead measurements, using a hierarchical model building process.

RESULTS

In total, 211 participants were recruited from Bangladesh, China, India, Pakistan and Sri Lanka. The distribution of the blood Pb varied by country of origin, and higher blood Pb values were found above 75th percentile compared to the CHMS. Distal factors significantly influencing blood Pb concentrations related to life history, such as duration of stay in Canada (RR=0.91; 95% CI 0.86-0.97), living near agricultural fields (RR=0.78; 95% CI 0.62-0.93), and country of origin. Proximal factors with significant contribution were use of cosmetics, traditional remedies, and smoking cigarettes.

RECOMMENDATIONS

Different past and current exposures may be important in various newcomer populations, informing international stakeholders, public health agencies, and primary care practitioners to adapt health education and exposure reduction programs to consider pre- and post-migration factors.

Exploring nighttime road traffic noise: A comprehensive predictive surface for Toronto, Canada

Road traffic noise can adversely impact the health of city residents, particularly when it occurs at night. The objective of this study was to evaluate nighttime traffic ambient noise in Toronto, Canada using measured and model-estimated noise levels. Road traffic noise was measured at 767 locations over 3 seasonal sampling campaigns between June 2012 and October 2013 to fully capture noise variability in Toronto. Temporal and campaign-specific spatial models, developed using the noise measurements, were used to build a final predictive surface. The surface was capable of estimating noise across the city over a 24-hr time frame. Measured and surface-estimated noise levels were compared with guidelines from the World Health Organization and the Province of Ontario to identify areas where noise may pose a health risk. Measured mean nighttime noise in Toronto exceeded World Health Organization (40 dBA) guidelines and mean daytime noise exceeded provincial (55 dBA) guidelines. The final predictive surface, incorporating spatial variables and daily cycles in noise levels, provides noise estimates geocoded for the entire study area. This tool could be used for epidemiological studies and to inform noise mitigation efforts. Based on surface-estimated noise levels during the quietest time of night (2 a.m.-2:30 a.m.), 100% of Toronto has nighttime noise exceeding 40 dBA (mean = 57 dBA, range = 49-110 dBA). A predictive surface was developed to estimate geocoded noise levels and facilitate further study of noise in Toronto. This tool can be used to assess road traffic noise, particularly at night, as an environmental health hazard.

Protective effect of yerba mate intake on the cardiovascular system: a post hoc analysis study in postmenopausal women

The prevalence of cardiovascular and metabolic diseases is increased in postmenopausal women, which contributes to the burden of illnesses in this period of life. Yerba mate (Ilex paraguariensis) is a native bush from Southern South America. Its leaves are rich in phenolic components, which may have antioxidant, vasodilating, hypocholesterolemic, and hypoglycemic proprieties. This post hoc analysis of the case-control study nested in the Obesity and Bone Fracture Cohort evaluated the consumption of yerba mate and the prevalence of hypertension, dyslipidemia, and coronary diseases in postmenopausal women. Ninety-five postmenopausal women were included in this analysis. A questionnaire was applied to evaluate the risk factors and diagnosis of cardiovascular diseases and consumption of yerba mate infusion. Student's t-test and chi-square test were used to assess significant differences between groups. The group that consumed more than 1 L/day of mate infusion had significantly fewer diagnoses of coronary disease, dyslipidemia, and hypertension (P<0.049, P<0.048, and P<0.016, respectively). Furthermore, the serum levels of glucose were lower in the group with a higher consumption of yerba mate infusion (P<0.013). The serum levels of total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides were similar between the groups. This pragmatic study points out the benefits of yerba mate consumption for the cardiovascular and metabolic systems. The ingestion of more than 1 L/day of mate infusion was associated with fewer self-reported cardiovascular diseases and lower serum levels of glucose. Longitudinal studies are needed to evaluate the association between yerba mate infusion and reduction of cardiovascular diseases in postmenopausal women.

Temporal trends in multiple sclerosis prevalence and incidence in a large population

Objective

We sought to better understand the reasons for increasing prevalence of multiple sclerosis (MS) by studying prevalence in relation to incidence, mortality rates, sex ratio, and geographic distribution of cases.

Methods

We identified MS cases from 1996 to 2013 in Ontario, Canada, by applying a validated algorithm to health administrative data. We calculated age- and sex-standardized prevalence and incidence rates for the province and by census division. Incidence and prevalence sex ratios for women to men were computed.

Results

The prevalence of MS increased by 69% from 1.57 (95% confidence interval [CI]: 1.54–1.59) per 1,000 in 1996 (n = 12,155) to 2.65 (95% CI: 2.62–2.68) in 2013 (n = 28,192). Incidence remained relatively stable except for a spike in 2010, followed by a subsequent decline in 2011–2013, particularly among young people and men. Mortality decreased by 33% from 26.7 (95% CI: 23.5–30.3) per 1,000 to 18.0 (95% CI: 16.4–19.8) per 1,000. The incidence sex ratio was stable from 1996 to 2009, then declined in 2010, with partial rebound by 2013. MS prevalence and incidence showed no consistent association with latitude.

Conclusion

In this large, population-based MS cohort, we found stable incidence and increasing prevalence of MS; the latter largely reflected declining mortality. A spike in incidence in 2010 among younger patients and men at a time of widespread media coverage of MS suggests that these groups may be vulnerable to delayed diagnosis. We did not find a latitudinal gradient; however, most Ontarians live between the 42nd and 46th parallels, reducing our ability to detect an effect of latitude.

Effect of air quality alerts on human health: a regression discontinuity analysis in Toronto, Canada

BACKGROUND

Ambient air pollution is a major health risk globally. To reduce adverse health effects on days when air pollution is high, government agencies worldwide have implemented air quality alert programmes. Despite their widespread use, little is known about whether these programmes produce any observable public-health benefits. We assessed the effectiveness of such programmes using a quasi-experimental approach.

METHODS

We assembled a population-based cohort comprising all individuals who resided in the city of Toronto (Ontario, Canada) from 2003 to 2012 (about 2·6 million people). We ascertained seven health outcomes known to be affected by short-term elevation of air pollution, using provincial health administrative databases. These health outcomes were cardiovascular-related mortality, respiratory-related mortality, and hospital admissions or emergency-department visits for acute myocardial infarction, heart failure, stroke, asthma, and chronic obstructive pulmonary disease (COPD). We applied a regression discontinuity design to assess the effectiveness of an intervention (ie, the air quality alert programme). To quantify the effect of the air quality alert programme, we estimated for each outcome both the absolute rate difference and the rate ratio attributable to programme eligibility (by intention-to-treat analysis) and the alerts themselves (by two-stage regression approach), respectively.

FINDINGS

Between Jan 1, 2003, and Dec 31, 2012, on average between three and 27 daily cardiovascular or respiratory events were reported in Toronto (depending on the outcome). Alert announcements reduced asthma-related emergency-department visits by 4·73 cases per 1 000 000 people per day (95% CI 0·55-9·38), or in relative terms by 25% (95% CI 1-47). Programme eligibility also led to 2·05 (95% CI 0·07-4·00) fewer daily emergency-department visits for asthma. We did not detect a significant reduction in any other health outcome as a result of alert announcements or programme eligibility. However, a non-significant trend was noted towards decreased asthma-related and COPD-related admissions.

INTERPRETATION

In this population-based cohort, the air quality alert programme was related to some reductions in respiratory morbidity, but not any other health outcome examined. This finding suggests that issuing air quality alerts alone has a limited effect on public health and that implementing enforced public actions to reduce air pollution on high pollution days could be warranted. Together with accumulating evidence of substantial burden from long-term air pollution exposure, this study underscores the need for further strengthening of global efforts that can lead to long-term improvement of overall air quality.

FUNDING

Public Health Ontario, Canadian Institutes for Health Research.

Increased coronary heart disease and stroke hospitalisations from ambient temperatures in Ontario

OBJECTIVE

To assess the associations between ambient temperatures and hospitalisations for coronary heart disease (CHD) and stroke.

METHODS

Our study comprised all residents living in Ontario, Canada, 1996-2013. For each of 14 health regions, we fitted a distributed lag non-linear model to estimate the cold and heat effects on hospitalisations from CHD, acute myocardial infarction (AMI), stroke and ischaemic stroke, respectively. These effects were pooled using a multivariate meta-analysis. We computed attributable hospitalisations for cold and heat, defined as temperatures above and below the optimum temperature (corresponding to the temperature of minimum morbidity) and for moderate and extreme temperatures, defined using cut-offs at the 2.5^th and 97.5^th temperature percentiles.

RESULTS

Between 1996 and 2013, we identified 1.4 million hospitalisations from CHD and 355 837 from stroke across Ontario. On cold days with temperature corresponding to the 1^st percentile of temperature distribution, we found a 9% increase in daily hospitalisations for CHD (95% CI 1% to 16%), 29% increase for AMI (95% CI 15% to 45%) and 11% increase for stroke (95% CI 1% to 22%) relative to days with an optimal temperature. High temperatures (the 99^th percentile) also increased CHD hospitalisations by 6% (95% CI 1% to 11%) relative to the optimal temperature. These estimates translate into 2.49% of CHD hospitalisations attributable to cold and 1.20% from heat. Additionally, 1.71% of stroke hospitalisations were attributable to cold. Importantly, moderate temperatures, rather than extreme temperatures, yielded the most of the cardiovascular burdens from temperatures.

CONCLUSIONS

Ambient temperatures, especially in moderate ranges, may be an important risk factor for cardiovascular-related hospitalisations.

Exposure to ambient air pollution and the incidence of dementia: A population-based cohort study

INTRODUCTION

Emerging studies have implicated air pollution in the neurodegenerative processes. Less is known about the influence of air pollution, especially at the relatively low levels, on developing dementia. We conducted a population-based cohort study in Ontario, Canada, where the concentrations of pollutants are among the lowest in the world, to assess whether air pollution exposure is associated with incident dementia.

METHODS

The study population comprised all Ontario residents who, on 1 April 2001, were 55-85years old, Canadian-born, and free of physician-diagnosed dementia (~2.1 million individuals). Follow-up extended until 2013. We used population-based health administrative databases with a validated algorithm to ascertain incident diagnosis of dementia as well as prevalent cases. Using satellite observations, land-use regression model, and an optimal interpolation method, we derived long-term average exposure to fine particulate matter (≤2.5μm in diameter) (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃), respectively at the subjects' historical residences based on a population-based registry. We used multilevel spatial random-effects Cox proportional hazards models, adjusting for individual and contextual factors, such as diabetes, brain injury, and neighborhood income. We conducted various sensitivity analyses, such as lagging exposure up to 10years and considering a negative control outcome for which no (or weaker) association with air pollution is expected.

RESULTS

We identified 257,816 incident cases of dementia in 2001-2013. We found a positive association between PM_2.5 and dementia incidence, with a hazard ratio (HR) of 1.04 (95% confidence interval (CI): 1.03-1.05) for every interquartile-range increase in exposure to PM_2.5. Similarly, NO₂ was associated with increased incidence of dementia (HR=1.10; 95% CI: 1.08-1.12). No association was found for O₃. These associations were robust to all sensitivity analyses examined. These estimates translate to 6.1% of dementia cases (or 15,813 cases) attributable to PM_2.5 and NO₂, based on the observed distribution of exposure relative to the lowest quartile in concentrations in this cohort.

DISCUSSION

In this large cohort, exposure to air pollution, even at the relative low levels, was associated with higher dementia incidence.

Adult and child urinary 2,4-D in cities with and without cosmetic pesticide bylaws: a population-based cross-sectional pilot study

We evaluated 2,4-dichlorophenoxyacetic acid (2,4-D) exposure in four municipalities with and without cosmetic pesticide bylaws in British Columbia, Canada. We recruited a child (aged 1.5-5 years) and adult from 10 households in each city, who provided urine samples in May and June, 2009. No households had used pesticides for 7 days prior to sample collection. We quantified urinary 2,4-D using LC/MS/MS. Quantities of 2,4-D in urine were similar across cities and below biomonitoring equivalents corresponding to references doses in the United State of America and Canada. When adult's and children's urines were analyzed together in linear mixed-effects regression models, natural log urinary 2,4-D was significantly associated with having a diet of ⩾50% organic food (β=-0.6 (0.3) μg/l, P=0.05). Without natural log transformation, median concentration of urinary 2,4-D among those who ate ⩾50% organic food (n=12) was 1.4 μg/l versus 1.5 μg/l for others (n=59). Lack of a significant association (two-sided alpha=0.05) between pesticide bylaws and urinary 2,4-D might reflect small sample size, lack of recent acute exposure, or that 2,4-D exposure is primarily influenced by sources of exposure not addressed through bylaws. Food might be a route of exposure to 2,4-D, consistent with other studies. Future research will require larger sample sizes for sufficient statistical power.

Blood cadmium concentrations and environmental exposure sources in newcomer South and East Asian women in the Greater Toronto Area, Canada

BACKGROUND

Immigrant women are often identified as being particularly vulnerable to environmental exposures and health effects. The availability of biomonitoring data on newcomers is limited, thus, presenting a challenge to public health practitioners in the identification of priorities for intervention.

OBJECTIVES

In fulfillment of data needs, the purpose of this study was to characterize blood concentrations of cadmium (Cd) among newcomer women of reproductive age (19-45 years of age) living in the Greater Toronto Area (GTA), Canada and to assess potential sources of environmental exposures.

METHODS

A community-based model, engaging peer researchers from the communities of interest, was used for recruitment and follow-up purposes. Blood samples were taken from a total of 211 newcomer women from South and East Asia, representing primary, regional origins of immigrants to the GTA, and environmental exposure sources were assessed via telephone survey. Metal concentrations were measured in blood samples (diluted with 0.5% (v/v) ammonium hydroxide and 0.1% (v/v) octylphenol ethoxylate) using a quadrupole ICP-MS. Survey questions addressed a wide range of environmental exposure sources, including dietary and smoking patterns and use of nutritional supplements, herbal products and cosmetics.

RESULTS

A geometric mean (GM) blood Cd concentration of 0.39µg/L (SD:±2.07µg/L) was determined for study participants (min/max: <0.045µg/L (LOD)/2.36µg/L). Several variables including low educational attainment (Relative Ratio (RR) (adjusted)=1.50; 95% CI 1.17-1.91), milk consumption (RR (adjusted)=0.86; 95% CI 0.76-0.97), and use of zinc supplements (RR (adjusted)=0.76; 95% CI 0.64-0.95) were observed to be significantly associated with blood Cd concentrations in the adjusted regression model. The variable domains socioeconomic status (R²_adj=0.11) and country of origin (R²_adj=0.236) were the strongest predictors of blood Cd.

CONCLUSION

Blood Cd concentrations fell below those generally considered to be of human health concern. However, negative health effects cannot be entirely excluded, especially for those that fall in the upper percentile range of the distribution, given the mounting evidence for negative health outcomes at low environmental exposure concentrations.

Living near major roads and the incidence of dementia, Parkinson's disease, and multiple sclerosis: a population-based cohort study

BACKGROUND

Emerging evidence suggests that living near major roads might adversely affect cognition. However, little is known about its relationship with the incidence of dementia, Parkinson's disease, and multiple sclerosis. We aimed to investigate the association between residential proximity to major roadways and the incidence of these three neurological diseases in Ontario, Canada.

METHODS

In this population-based cohort study, we assembled two population-based cohorts including all adults aged 20-50 years (about 4·4 million; multiple sclerosis cohort) and all adults aged 55-85 years (about 2·2 million; dementia or Parkinson's disease cohort) who resided in Ontario, Canada on April 1, 2001. Eligible patients were free of these neurological diseases, Ontario residents for 5 years or longer, and Canadian-born. We ascertained the individual's proximity to major roadways based on their residential postal-code address in 1996, 5 years before cohort inception. Incident diagnoses of dementia, Parkinson's disease, and multiple sclerosis were ascertained from provincial health administrative databases with validated algorithms. We assessed the associations between traffic proximity and incident dementia, Parkinson's disease, and multiple sclerosis using Cox proportional hazards models, adjusting for individual and contextual factors such as diabetes, brain injury, and neighbourhood income. We did various sensitivity analyses, such as adjusting for access to neurologists and exposure to selected air pollutants, and restricting to never movers and urban dwellers.

FINDINGS

Between 2001, and 2012, we identified 243 611 incident cases of dementia, 31 577 cases of Parkinson's disease, and 9247 cases of multiple sclerosis. The adjusted hazard ratio (HR) of incident dementia was 1·07 for people living less than 50 m from a major traffic road (95% CI 1·06-1·08), 1·04 (1·02-1·05) for 50-100 m, 1·02 (1·01-1·03) for 101-200 m, and 1·00 (0·99-1·01) for 201-300 m versus further than 300 m (p for trend=0·0349). The associations were robust to sensitivity analyses and seemed stronger among urban residents, especially those who lived in major cities (HR 1·12, 95% CI 1·10-1·14 for people living <50 m from a major traffic road), and who never moved (1·12, 1·10-1·14 for people living <50 m from a major traffic road). No association was found with Parkinson's disease or multiple sclerosis.

INTERPRETATION

In this large population-based cohort, living close to heavy traffic was associated with a higher incidence of dementia, but not with Parkinson's disease or multiple sclerosis.

FUNDING

Health Canada (MOA-4500314182).

Residents of highly walkable neighbourhoods in Canadian urban areas do substantially more physical activity: a cross-sectional analysis

BACKGROUND

Research has shown that neighbourhood walkability is associated with small differences in physical activity; however, the health impacts of these small differences have been questioned. We examined the size of the association of walkability with accelerometer-measured physical activity in a large, national-level Canadian population, and compared results to physical activity levels recommended in international guidelines. Our primary objective was to investigate the direction and size of the differences in physical activity that were related to walkability, and whether these differences depended on age.

METHODS

Participants were included from among respondents to the 2007-2011 Canadian Health Measures Surveys who lived in urban areas and were aged 6-79 years. The Canadian Health Measures Surveys are ongoing cross-sectional surveys of a Canada-wide population. Respondents were divided into quintiles based on Street Smart Walk Score® values of their census dissemination areas. For all respondents and age subgroups, we used covariate-adjusted generalized linear models to estimate differences between quintiles in accelerometer-measured moderate-to-vigorous physical activity (MVPA) and sedentary time.

RESULTS

We included 7180 respondents. Differences in participant MVPA between highest and lowest Street Smart Walk Score quintiles were 3.2 (95% confidence interval [CI] -3.2 to 9.6) minutes/day for ages 6-11 years, 11.4 (95% CI 5.3 to 17.4) minutes/day for ages 12-17 years, 9.9 (95% CI 2.4 to 17.4) minutes/day for ages 18-29 years, 14.9 (95% CI 10.2 to 19.6) minutes/day for ages 30-44 years, 11.5 (95% CI 6.7 to 16.3) minutes/day for ages 45-64 years and 6.9 (95% CI 3.1 to 10.8) minutes/day for ages 65-79 years. There were no significant differences in sedentary time in any age group.

INTERPRETATION

In all groups except the youngest, participants in the most walkable areas did significantly more MVPA than those in the least walkable areas. For several age groups, this difference was approximately one-half to two-thirds of the amount recommended in guidelines for physical activity. Substantially higher MVPA levels suggest that residents of highly walkable areas may have greater health benefits.

Ambient Temperature and the Risk of Renal Colic: A Population-Based Study of the Impact of Demographics and Comorbidity

PURPOSE

To examine the impact of ambient temperature on the incidence of emergency department (ED) admissions for acute renal colic and the potential influence demographics and comorbid conditions may have on this.

METHODS

We conducted a population-based time series analysis using linked healthcare databases in Ontario, Canada, which included all residents, aged ≥19 years, who were admitted to an ED from April 2002 to December 2013. The primary outcome was daily number of renal colic emergency department admissions. A distributed lag nonlinear model with 21 days of lag was applied to estimate the cumulative effect of temperature on colic admissions. We estimated risks for cold and heat, defined as temperatures below and above the optimal temperature, which corresponded to the point with minimum risk of colic admissions. We conducted stratified analyses using selected demographics and comorbidities.

RESULTS

During the study period, 423,396 patients presented to an ED with colic. There was a significantly increased risk of colic as ambient temperature increased (rate ratio [RR] = 1.30, 95% confidence interval [CI]: 1.20, 1.42). Subgroup analysis demonstrated an increased risk associated with heat for both genders; however, this risk was more pronounced in males with extreme heat (RR = 1.64 vs 1.22, p = 0.006). In contrast to other age groups, there was an increased risk for those in their 40s (RR = 1.42), 50s (RR = 1.54), and 60s (RR = 1.31) (p = 0.02).

CONCLUSION

Increasing ambient temperature was associated with increased risk of ED visits for colic, particularly in males and those aged 40 to 69 years.

Ambient Fine Particulate Matter and Mortality among Survivors of Myocardial Infarction: Population-Based Cohort Study

BACKGROUND

Survivors of acute myocardial infarction (AMI) are at increased risk of dying within several hours to days following exposure to elevated levels of ambient air pollution. Little is known, however, about the influence of long-term (months to years) air pollution exposure on survival after AMI.

OBJECTIVE

We conducted a population-based cohort study to determine the impact of long-term exposure to fine particulate matter ≤ 2.5 μm in diameter (PM2.5) on post-AMI survival.

METHODS

We assembled a cohort of 8,873 AMI patients who were admitted to 1 of 86 hospital corporations across Ontario, Canada in 1999-2001. Mortality follow-up for this cohort extended through 2011. Cumulative time-weighted exposures to PM2.5 were derived from satellite observations based on participants' annual residences during follow-up. We used standard and multilevel spatial random-effects Cox proportional hazards models and adjusted for potential confounders.

RESULTS

Between 1999 and 2011, we identified 4,016 nonaccidental deaths, of which 2,147 were from any cardiovascular disease, 1,650 from ischemic heart disease, and 675 from AMI. For each 10-μg/m3 increase in PM2.5, the adjusted hazard ratio (HR10) of nonaccidental mortality was 1.22 [95% confidence interval (CI): 1.03, 1.45]. The association with PM2.5 was robust to sensitivity analyses and appeared stronger for cardiovascular-related mortality: ischemic heart (HR10 = 1.43; 95% CI: 1.12, 1.83) and AMI (HR10 = 1.64; 95% CI: 1.13, 2.40). We estimated that 12.4% of nonaccidental deaths (or 497 deaths) could have been averted if the lowest measured concentration in an urban area (4 μg/m3) had been achieved at all locations over the course of the study.

CONCLUSIONS

Long-term air pollution exposure adversely affects the survival of AMI patients.

CITATION

Chen H, Burnett RT, Copes R, Kwong JC, Villeneuve PJ, Goldberg MS, Brook RD, van Donkelaar A, Jerrett M, Martin RV, Brook JR, Kopp A, Tu JV. 2016. Ambient fine particulate matter and mortality among survivors of myocardial infarction: population-based cohort study. Environ Health Perspect 124:1421-1428; http://dx.doi.org/10.1289/EHP185.

Hospitalizations from Hypertensive Diseases, Diabetes, and Arrhythmia in Relation to Low and High Temperatures: Population-Based Study

Little is known about the extent to which ambient temperatures contribute to the burden of hospitalizations from hypertensive diseases, diabetes, and arrhythmia. To fill this knowledge gap, we conducted a time-series study comprising entire population of Ontario, Canada during 1996–2013. A distributed lag non-linear model was developed to estimate the cumulative effect of temperatures over a 21-day lag period. We computed the burden of hospitalizations attributable to cold and heat. Furthermore, we separated the burden into components related to mild and extreme temperatures. Compared to the temperature with minimum risk of morbidity, cold temperatures (1^st percentile) were associated with a 37% (95% confidence interval: 5%, 78%) increase in hypertension-related hospitalizations whereas no significant association with hot temperatures (99^th percentile) was observed. Cold and hot temperatures were also associated with a 12% (1%, 24%) and a 30% (6%, 58%) increase in diabetes-related hospitalizations, respectively. Arrhythmia was not linked to temperatures. These estimates translate into ~10% of hypertension-related hospitalizations attributable to total cold, and ~9% from mild cold. Similarly, ~11% of diabetes-related hospitalizations were due to total heat, virtually all of which were from mild heat. In conclusion, ambient temperatures, especially in moderate ranges, contribute to excess hospitalizations from hypertension and diabetes.

Arsenic from community water fluoridation: quantifying the effect

Community water fluoridation is a WHO recommended strategy to prevent dental carries. One debated concern is that hydrofluorosilicic acid, used to fluoridate water, contains arsenic and poses a health risk. This study was undertaken to determine if fluoridation contributes to arsenic in drinking water, to estimate the amount of additional arsenic associated with fluoridation, and compare this to the National Sanitation Foundation/American National Standards Institute (NSF/ANSI) standard and estimates from other researchers. Using surveillance data from Ontario drinking water systems, mixed effects linear regression was performed to examine the effect of fluoridation status on the difference in arsenic concentration between raw water and treated water samples. On average, drinking water treatment was found to reduce arsenic levels in water in both fluoridated and non-fluoridated systems by 0.2 μg/L. However, fluoridated systems were associated with an additional 0.078 μg/L (95% CI 0.021, 0.136) of arsenic in water when compared to non-fluoridated systems (P = 0.008) while controlling for raw water arsenic concentrations, types of treatment processes, and source water type. Our estimate is consistent with concentrations expected from other research and is less than 10% of the NSF/ANSI standard of 1 μg/L arsenic in water. This study provides further information to inform decision-making regarding community water fluoridation.

Assessment of the effect of cold and hot temperatures on mortality in Ontario, Canada: a population-based study

BACKGROUND

Ambient high temperature is associated with death; however, heat-related risk of death has not been quantified systematically in Ontario, the most populous province in Canada. Less is known about cold-related risk in this population. Our objective was to quantify the health impact from cold and hot temperatures in Ontario.

METHODS

The study population consisted of all residents of Ontario who died between Jan. 1, 1996, and Dec. 31, 2010, from any nonaccidental cause. A case-crossover analysis was applied to assess the relation between daily temperature fluctuation and deaths from nonaccidental and selected causes in cold (December-February) and warm (June-August) seasons, respectively, adjusting for various potential confounders. Risk estimates were obtained for each census division, then pooled across Ontario. We examined potential effect modification for selected comorbidities and sociodemographic characteristics.

RESULTS

In warm seasons, each 5°C increase in daily mean temperature was associated with a 2.5% increase in nonaccidental deaths (95% confidence interval [CI] = 1.3% to 3.8%) on the day of exposure (lag 0). In cold seasons, each 5°C decrease in daily temperature was associated with a 3.0% (95% CI 1.8% to 4.2%) increase in nonaccidental deaths, which persisted over 7 days (lag 0-6). The cold-related effects (lag 0-6) were stronger for cardiovascular-related deaths (any cardiovascular death: 4.1%, 95% CI 2.3% to 5.9%; ischemic heart disease: 5.8%, 95% CI 3.6% to 8.1%), especially among people less than 65 years of age (8.0%, 95% CI 3.0% to 13.0%). Conversely, heat most strongly increased respiratory-related deaths during admission to hospital (26.0%, 95% CI 0% to 61.4%). Across Ontario, each 5°C change in daily temperature was estimated to induce 7 excess deaths per day in cold seasons and 4 excess deaths in warm seasons.

INTERPRETATION

Heat contributed to excess deaths in Ontario, although the effect of cold weather appeared to be greater. Further work is required to better define high-risk subgroups, which might include the homeless and people with inadequately heated housing.

Neighborhood walkability: Differential associations with self-reported transport walking and leisure-time physical activity in Canadian towns and cities of all sizes

OBJECTIVE

To estimate associations between walkability and physical activity during transportation and leisure in a national-level population.

METHODS

Walkability was measured by Walk Score® (2012-2014) and physical activity by the Canadian Community Health Survey (2007-2012) for urban participants who worked or attended school. Multiple linear regression was done on the total study population, four age subgroups (12-17, 18-29, 30-64, 65+) and three population center subgroups (1000-29,999, 30,000-99,999, 100,000+).

RESULTS

151,318 respondents were examined. Comparing highest to lowest Walk Score® quintiles, covariate-adjusted energy expenditure on transport walking [95% confidence interval] was 0.17 [0.15, 0.18] kcal/kg/day higher in the total study population, and significantly higher in all age and population center subgroups. Leisure physical activity was lower in the age 18-29 subgroup (-0.28 [-0.43, -0.12]) and population centers 100,000+ subgroup (-0.10 [-0.18, -0.03]), but higher in the population centers 1000-29,999 subgroup (0.30 [0.12, 0.48]). Total physical activity was higher in the following subgroups: age 30-64 (0.19 [0.12, 0.26]), population centers 100,000+ (0.12 [0.04, 0.19]) and population centers 1000-29,999 (0.40 [0.20, 0.59]).

CONCLUSIONS

Walkability is associated with transport walking in all age groups and towns and cities of all sizes. Walkability's inverse associations with leisure physical activity among young adults and in large population centers may offset energy expenditure gains, while positive associations with leisure physical activity in small centers may add to energy expenditure.

Air pollution and the development of posttransplant chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) is the leading cause of mortality following lung transplantation. We conducted a retrospective cohort study including 397 bilateral lung recipients transplanted in from 1996 to 2009 to determine the association between ambient air pollution, CLAD and mortality. Pollution exposure was assessed using satellite-based estimates of nitrogen dioxide, distance to major roadway and total length of roadways around a patient's home. Cumulative exposures to ozone and particulate matter were estimated from concentrations measured at fixed-site stations near patients' homes using inverse distance weighted interpolation. Cox proportional hazards models were used to estimate the associations of CLAD with air pollution exposure, adjusting for various individual and neighborhood characteristics. During the follow-up, 185 patients developed CLAD (47%) and 101 patients died (25%). Fifty-four deaths (53%) were due to CLAD. We observed an association between CLAD development and road density within 200 m of a patient's home (HR 1.30 [95% CI 1.07-1.58]). Although based on a subgroup of 14 patients, living within 100 m of a highway was associated with a high risk for developing CLAD (HR 4.91 [95% CI 2.22, 10.87]). These data suggest that exposure to traffic-related air pollution is associated with development of CLAD among lung transplant recipients.

Temporal and spatial variability of traffic-related noise in the City of Toronto, Canada

The majority of studies that assessed population-level exposure to traffic-related noise were conducted in European countries and less is known about the exposure to traffic noise in North America, particularly in Canadian cities. This study explored the temporal and spatial variability of traffic noise in the City of Toronto, the largest city in Canada. We conducted two cycles of intensive field measurement campaign to collect real-time measurements of traffic noise at 554 locations across Toronto between June 2012 and January 2013. At each site, we collected measurements for a period of 30 min during daytime. Repeated measurements were made in cycle two at 62 locations randomly selected from cycle one, which exhibited high correlation (Pearson's correlation coefficient (r): 0.79). In addition, continuous measurements of noise were recorded for seven days at ten sites. We observed that noise variability was predominantly spatial in nature, rather than temporal: spatial variability accounted for 60% of the total observed variations in traffic noise. Traffic volume, length of arterial road, and industrial area were three most important variables, explaining the majority of the spatial variability of noise (R(2)=0.68 to 0.74, depending on the cycle). In comparison to the 16-h equivalent sound level guideline for outdoor locations set out by the Ministry of the Environment of the Province of Ontario, 80% of our sampled locations exceeded this guideline (i.e. 55 dBA,16 h). These findings suggested ubiquitous traffic noise exposure across Toronto and that noise variability was explained mostly by spatial characteristics.

Spatial association between ambient fine particulate matter and incident hypertension

BACKGROUND

Laboratory studies suggest that exposure to fine particulate matter (≤2.5 μm in diameter) (PM2.5) can trigger a combination of pathophysiological responses that may induce the development of hypertension. However, epidemiological evidence relating PM2.5 and hypertension is sparse. We thus conducted a population-based cohort study to determine whether exposure to ambient PM2.5 is associated with incident hypertension.

METHODS AND RESULTS

We assembled a cohort of 35 303 nonhypertensive adults from Ontario, Canada, who responded to 1 of 4 population-based health surveys between 1996 and 2005 and were followed up until December 31, 2010. Incident diagnoses of hypertension were ascertained from the Ontario Hypertension Database, a validated registry of persons diagnosed with hypertension in Ontario (sensitivity=72%, specificity=95%). Estimates of long-term exposure to PM2.5 at participants' postal-code residences were derived from satellite observations. We used Cox proportional hazards models, adjusting for various individual and contextual risk factors including body mass index, smoking, physical activity, and neighbourhood-level unemployment rates. We conducted various sensitivity analyses to assess the robustness of the effect estimate, such as investigating several time windows of exposure and controlling for potential changes in the risk of hypertension over time. Between 1996 and 2010, we identified 8649 incident cases of hypertension and 2296 deaths. For every 10-µg/m(3) increase of PM2.5, the adjusted hazard ratio of incident hypertension was 1.13 (95% confidence interval, 1.05-1.22). Estimated associations were comparable among all sensitivity analyses.

CONCLUSIONS

This study supports an association between PM2.5 and incident hypertension.

Peak event analysis: a novel empirical method for the evaluation of elevated particulate events

BACKGROUND

We report on a novel approach to the analysis of suspended particulate data in a rural setting in southern Ontario. Analyses of suspended particulate matter and associated air quality standards have conventionally focussed on 24-hour mean levels of total suspended particulates (TSP) and particulate matter <10 microns, <2.5 microns and <1 micron in diameter (PM10, PM2.5, PM1, respectively). Less emphasis has been placed on brief peaks in suspended particulate levels, which may pose a substantial nuisance, irritant, or health hazard. These events may also represent a common cause of public complaint and concern regarding air quality.

METHODS

Measurements of TSP, PM10, PM2.5, and PM1 levels were taken using an automated device following local complaints of dusty conditions in rural south-central Ontario, Canada. The data consisted of 126,051 by-minute TSP, PM10, PM2.5, and PM1 measurements between May and August 2012. Two analyses were performed and compared. First, conventional descriptive statistics were computed by month for TSP, PM10, PM2.5, and PM1, including mean values and percentiles (70th, 90th, and 95th). Second, a novel graphical analysis method, using density curves and line plots, was conducted to examine peak events occurring at or above the 99th percentile of per-minute TSP readings. We refer to this method as "peak event analysis". Findings of the novel method were compared with findings from the conventional approach.

RESULTS

Conventional analyses revealed that mean levels of all categories of suspended particulates and suspended particulate diameter ratios conformed to existing air quality standards. Our novel methodology revealed extreme outlier events above the 99th percentile of readings, with peak PM10 and TSP levels over 20 and 100 times higher than the respective mean values. Peak event analysis revealed and described rare and extreme peak dust events that would not have been detected using conventional descriptive statistics.

CONCLUSIONS

Peak event analysis underscored extreme particulate events that may contribute to local complaints regarding intermittently dusty conditions. These outlier events may not appear through conventional analytical approaches. In comparison with conventional descriptive approaches, peak event analysis provided a more analytical and data-driven means to identify suspended particulate events with meaningful and perceptible effects on local residents.

Risk of incident diabetes in relation to long-term exposure to fine particulate matter in Ontario, Canada

BACKGROUND

Laboratory studies suggest that fine particulate matter (≤ 2.5 µm in diameter; PM(2.5)) can activate pathophysiological responses that may induce insulin resistance and type 2 diabetes. However, epidemiological evidence relating PM2.5 and diabetes is sparse, particularly for incident diabetes.

OBJECTIVES

We conducted a population-based cohort study to determine whether long-term exposure to ambient PM(2.5) is associated with incident diabetes.

METHODS

We assembled a cohort of 62,012 nondiabetic adults who lived in Ontario, Canada, and completed one of five population-based health surveys between 1996 and 2005. Follow-up extended until 31 December 2010. Incident diabetes diagnosed between 1996 and 2010 was ascertained using the Ontario Diabetes Database, a validated registry of persons diagnosed with diabetes (sensitivity = 86%, specificity = 97%). Six-year average concentrations of PM2.5 at the postal codes of baseline residences were derived from satellite observations. We used Cox proportional hazards models to estimate the associations, adjusting for various individual-level risk factors and contextual covariates such as smoking, body mass index, physical activity, and neighborhood-level household income. We also conducted multiple sensitivity analyses. In addition, we examined effect modification for selected comorbidities and sociodemographic characteristics.

RESULTS

There were 6,310 incident cases of diabetes over 484,644 total person-years of follow-up. The adjusted hazard ratio for a 10-µg/m(3) increase in PM(2.5) was 1.11 (95% CI: 1.02, 1.21). Estimated associations were comparable among all sensitivity analyses. We did not find strong evidence of effect modification by comorbidities or sociodemographic covariates.

CONCLUSIONS

This study suggests that long-term exposure to PM2.5 may contribute to the development of diabetes.

Tattooing and risk of hepatitis B: a systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review and meta-analysis is to assess the association between tattooing and the risk of transmission of hepatitis B virus.

METHODS

A systematic search of MEDLINE, EMBASE, PubMed, Database of Abstracts of Reviews of Effects, ACP Journal Club and BIOSIS Previews was performed up to March 2011.

RESULTS

Forty-two observational studies were included in this systematic review, of which 31 were included in the meta-analysis. Pooled odds ratios (95% confidence intervals) of the association of tattooing and hepatitis B infection was 1.48 (1.30-1.68) when all studies were included in the analysis. Subgroup analysis shows the strongest association between tattooing and risk of hepatitis B among populations involved in high-risk behaviours (OR = 1.64, 95% CI: 1.32-2.03).

CONCLUSION

Findings of the current systematic review and meta-analysis indicate that tattooing is associated with hepatitis B transmission in all subgroups. A population health approach that emphasizes universal hepatitis B immunization, education of young adults who are more likely to get tattoos, and education of prison inmates (who have the highest background rate of hepatitis B infection), along with enforcement of guidelines and safer tattooing practices in prison, are fundamental in prevention of transmission of hepatitis B.