مقاله انگلیسی رایگان در مورد قرار گرفتن در معرض آلودگی هوا و خطر ابتلا به سرطان – الزویر 2019

abstract

The relationship between air pollution and childhood cancer is inconclusive. We investigated the associations between exposure to ambient air pollution and childhood cancers in Tehran, Iran. This project included children between 1 and 15 years-of-age with a cancer diagnosis by the Center for the Control of Non Communicable Disease (n = 161) during 2007 to 2009. Controls were selected randomly within the city using a Geographic Information System (GIS) (n = 761). The cases were geocoded based on exact home addresses. Air pollution exposure of cases and random controls were estimated by a previously developed Land Use Regression (LUR) model for the 2010 calendar year. The annual mean concentrations of Particulate Matter ≤ 10 μm (PM10), nitrogen dioxide (NO2) and sulfur dioxide (SO2) in the locations of cancer cases were 101.97 μg/m3 , 49.42 ppb and 38.92 ppb respectively, while in the random control group, respective mean exposures were 98.63 μg/m3 , 45.98 ppb and 38.95 ppb. A logistic regression model was used to find the probability of childhood cancer per unit increase in PM10, NO2 and SO2. We observed a positive association between exposures to PM10 with childhood cancers. We did, however, observe a positive, but not statistically significant association between NO2 exposure and childhood cancer. Our study is the first to highlight an association between air pollution exposure and childhood cancer risk in Iran, however these findings require replication through future studies.

Introduction

There is a growing body of literature describing the risks associated with proximity to urban air pollution (Brunekreef and Holgate, 2002; Raaschou-Nielsen and Reynolds, 2006; Forouzanfar et al., 2015). Air pollution exposure has been shown to have serious negative health consequences (Chen et al., 2016; Morawska et al., 1999). Cancer incidence and mortality rates in urban communities are far higher than in rural societies (Ziegler et al., 1993; Kunzli et al., 2000); with air pollution being recognized as one of the most important public health issues in an urban setting (Selden and Song, 1994). Urban and industrial development and increasing economic activity tend to increase pollution levels in cities (Wheeler, 2001). In Tehran, as in many other industrial cities, the major sources of air pollutants include motor vehicles, industry and domestic sources (Asadollah-Fardi, 2008). Tehran acquires about 80–85% of its major air pollutants, which include PM10, NO2, SO2, HC, O3 and CO, from mobile sources (Naddafi et al., 2012). A wide range of adverse health consequences due to short and longterm exposure to air pollutants have been recorded in urban populations throughout the world (Pope III and Dockery, 2006; Naddafi et al., 2012). Globally, cancer is one of the major causes of childhood death. Childhood cancer incidence rates among white children are 120–150 diagnoses per million boys and 110–140 per million girls annually within Europe, North and South America, Australia and New Zealand, all of which routinely register cancer cases (Parkin et al., 1988). In Iran, the third highest cause of deaths is cancer incidence, after coronary heart disease and accidents (Naghavi and Jafari, 2007). Cancer is responsible for 4% of the deaths in children under 5 years-of-age and 13% of deaths in children 5–15 years-of-age in the Iranian population; contributing to a total 15% of loss of life in the under 15-years-of-age population (Mosavi-Jarrahi et al., 2007). Some epidemiological studies have shown that an increase in childhood cancer risk is related to traffic exposure (Reynolds et al., 2002; Reynolds et al., 2004; Feychting et al., 1998; Raaschou-Nielsen et al., 2001; Elliott et al., 2017). Nevertheless, the evidence for an association between our air pollutants of interest and childhood cancer is weak; few positive findings were obtained in a small number of studies which featured small sample size, unreliable exposure assessment methods and other methodological limitations (Raaschou-Nielsen and Reynolds, 2006).