Elsevier

Environment International

Volume 80, July 2015, Pages 26-32
Environment International

Chronic disease prevalence in women and air pollution — A 30-year longitudinal cohort study

https://doi.org/10.1016/j.envint.2015.03.017Get rights and content

Highlights

  • We examine the association of PM2.5 exposure with prevalence of major chronic diseases in women.

  • Cumulative PM2.5 data were collected from satellite-based estimates of surface concentrations.

  • Increased exposure increases risk of cancer, diabetes, and cardiovascular and respiratory diseases.

  • The effect of PM2.5 exposure and disease prevalence was markedly larger in smokers and obese women.

Abstract

Background

Air pollution, such as fine particulate matter (PM2.5), can increase risk of adverse health events among people with heart disease, diabetes, asthma and chronic obstructive pulmonary disease (COPD) by aggravating these conditions. Identifying the influence of PM2.5 on prevalence of these conditions may help target interventions to reduce disease morbidity among high-risk populations.

Objectives

The objective of this study is to measure the association of exposure of PM2.5 with prevalence risk of various chronic diseases among a longitudinal cohort of women.

Methods

Women from Ontario who enrolled in the Canadian National Breast Screening Study (CNBSS) from 1980 to 1985 (n = 29,549) were linked to provincial health administrative data from April 1, 1992 to March 31, 2013 to determine the prevalence of major chronic disease and conditions (heart disease, diabetes, asthma, COPD, acute myocardial infarction, angina, stroke and cancers). Exposure to PM2.5 was measured using satellite data collected from January 1, 1998 to December 31, 2006 and assigned to resident postal-code at time of entry into study. Poisson regression models were used to describe the relationship between exposure to ambient PM2.5 and chronic disease prevalence. Prevalence rate ratios (PRs) were estimated while adjusting for potential confounders: baseline age, smoking, BMI, marital status, education and occupation. Separate models were run for each chronic disease and condition.

Results

Congestive heart failure (PR = 1.31, 95% CI: 1.13, 1.51), diabetes (PR = 1.28, 95% CI: 1.16, 1.41), ischemic heart disease (PR = 1.22, 95% CI: 1.14, 1.30), and stroke (PR = 1.21, 95% CI: 1.09, 1.35) showed over a 20% increase in PRs per 10 μg/m3 increase in PM2.5 after adjusting for risk factors. Risks were elevated in smokers and those with BMI greater than 30.

Conclusions

This study estimated significant elevated prevalent rate ratios per unit increase in PM2.5 in nine of the ten chronic diseases studied.

Introduction

The adverse health effects associated with exposure to ambient air pollution, particularly traffic-related pollution, have been well established. In recent years, there has been extensive literature suggesting an increased risk in the incidence and mortality of several chronic diseases in association with long-term exposure to air pollutants. The biological plausibility is that air pollutants may promote inflammation, oxidative stress and endothelial dysfunction that may contribute to the development of chronic conditions such as cardiovascular disease, hypertension and diabetes (Brook et al., 2004, Coogan et al., 2012, Johnson and Parker, 2009, Kramer et al., 2010, Pearson et al., 2010, Puett et al., 2011, EPA, 2008, EPA, 2009, EPA, 2013). In addition, air pollution has also been linked to the worsening of diseases of the pulmonary system, including asthma and chronic obstructive pulmonary disease (COPD) (To et al., 2013a, To et al., 2013b). Older adults living with a chronic condition such as hypertension, asthma and COPD may be at higher risk of having their conditions aggravated by exposure to air pollution.

A few population-based studies have quantified the association of air pollution exposure and incidence of chronic disease. For example, using data from Ontario, Canada, Chen et al., 2013, Chen et al., 2014 reported significantly elevated hazard ratios of incident hypertension and diabetes (HR = 1.13, 95% confidence interval: 1.05–1.22 and HR = 1.11; 95% CI: 1.02, 1.21, respectively) per 10-μg/m3 increase of PM2.5. Coogan et al. (2012) studied a cohort of 4204 women who lived in Los Angeles from 1995 to 2005 and reported elevated incidence rate ratios for hypertension and diabetes per unit (10 μg/m3) increase in fine particulate matter (PM2.5). Puett et al. (2011) used data from the final two years of a 23-year follow-up of the Nurses' Health Study and reported a statistically significant relative risk of type 2 diabetes per unit (4 μg/m3) increase of PM2.5. Johnson and Parker (2009) conducted cross-sectional analyses using the National Health Interview Survey data and reported statistically significant increased odds of self-reported prevalent hypertension associated with PM2.5.

In this study, we used a large population-based cohort of women with over 30 years of follow-up data to quantify the prevalence risks of cardiovascular conditions, cancers, diabetes and respiratory diseases in association with PM2.5 exposure. Since these conditions and diseases are chronic (i.e., with a relatively long duration), measures of disease prevalence would better characterize the burden of illness than incidence. A better understanding of the long-term risks of exposure to air pollution on these major chronic conditions will enable the development of new strategies to protect individuals at risk and reduce detrimental effects of air pollution on health as a whole.

Section snippets

Study population

The Canadian National Breast Screening Study (CNBSS) included 89,835 women between the ages of 40 and 59 recruited between 1980 and 1985 (Miller et al., 1992, Miller et al., 1996). The CNBSS was a randomized controlled trial of screening for breast cancer with the original objective of determining whether screening contributed to lower breast cancer mortality, as well as answering questions about what ages to screen and frequency of screening. Detailed risk factor data were collected using

Results

Table 1 shows the demographic characteristics of the ONBSS population. The study population consisted of 29,549 women with valid health card number for data linkage, which represented 92.4% of the total ONBSS cohort. Approximately 79% of these women were still alive at the end of the study (March 31, 2013) with a mean age of 77.3 years (± 6.3). The majority of the women were Canadian born (72.6%), married (81.1%), had at least completed high school education (81.4%) and were in the workforce

Discussion

To date, this is one of the largest longitudinal cohort studies examining the impact of air quality on the prevalence of major cardiovascular conditions, cancer, diabetes and respiratory diseases in women. This study estimated significant elevated prevalence per unit increase in PM2.5 for nine out of the ten chronic diseases studied.

The ONBSS study population consisted of nearly 30,000 women who were recruited for the CNBSS in the 1980s when they were between 40 and 59 years of age. The majority

Role of funding source

Funding for this study is provided by a research contract with Health Canada (Contract Reference #: 4500306095). Neither Health Canada nor ICES had any role in study design, analysis, interpretation of data, or writing of the report. The opinions, results and conclusions presented in this report are those of the authors and are independent from the funding sources. No endorsement by Health Canada or ICES is intended or should be inferred.

Contributors

TT and PV initiated and designed the study, interpreted findings and drafted the manuscript. JZ conducted all statistical analysis. JS, LF, CG and DW conducted a search of the literature, summarized relevant study findings and reviewed the manuscript. JS, HC, PV, SW, CW and ABM interpreted findings, reviewed and commented on drafts. All authors have seen and approved the final version.

Conflicts of interest

We declare that we have no conflicts of interest.

Acknowledgments

Data were provided by the CNBSS and ICES.

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