Characteristics and Potential Inhalation Exposure Risks of Environmentally Persistent Free Radicals in Atmospheric Particulate Matter and Solid Fuel Combustion Particles in High Lung Cancer Incidence Area, China

Kai Xiao,Qingyue Wang,Christian Ebere Enyoh,Mominul Haque Rabin,Yichun Lin,Senlin Lu,Tanzin Chowdhury,Weiqian Wang

doi:10.3390/atmos12111467

Abstract

Environmentally persistent free radicals (EPFRs) were previously considered an unrecognized composition of air pollutants and might help explain the long-standing medical mystery of why non-smokers develop tobacco-related diseases such as lung cancer. However, there is no investigated on EPFRs in Xuanwei rural areas, especially in high prevalence of lung cancer areas. In this study, we selected six types of coal and three types of biomass in Xuanwei, then conducted simulated combustion, and six group of atmospheric particulate matters (APMs) to explore the content and particle size distribution pattern of EPFRs and a new health risk assessment method to evaluate the risk of EPFRs in PM for adults and children. Our results show that the contribution of EPFRs for biomass combustion, coal combustion and APMs were mainly distributed in the size range of <1.1 μm, which accounted for 76.15 ± 4.14%, 74.85 ± 10.76%, and 75.23 ± 8.18% of PM3.3. The mean g factors and ΔHp-p indicated that the EPFRs were mainly oxygen-centered radicals in PM in Xuanwei. The results suggest that the health risk of EPFRs is significantly increased when the particle size distribution of EPFRs is taken into account, and coal combustion particulate matter (174.70 ± 37.86 cigarettes for an adult, 66.39 ± 14.39 cigarettes per person per year for a child) is more hazardous to humans than biomass combustion particulate matter (69.41 ± 4.83 cigarettes for an adult, 26.37 ± 1.84 cigarettes per person per year for), followed by APMs (102.88 ± 39.99 cigarettes for an adult, 39.10 ±15.20 cigarettes per person per year for) in PM3.3. Our results provides a new perspective and evidence for revealing the reason for the high incidence of lung cancer in Xuanwei, China.

Highlights

Science Co., Ltd., Saitama, Japan) to explore the content and particle size distribution pattern of Environmentally persistent free radicals (EPFRs) and health risk assessment of EPFRs in particulate matter produced by different sources, providing new perspectives and evidence to reveal the high incidence of lung cancer in Xuanwei
Numerous studies have been conducted on EPFRs in atmospheric particulate matter [22,26,32,42], but there is a lack of studies on EPFRs in particulate matter emitted directly from raw coal combustion and biomass combustion
The results of this study suggest that the health risk of EPFRs is significantly increased when the particle size distribution of EPFRs is taken into account, and coal combustion particulate matter is more hazardous to humans than combustion particulate matter, followed by atmospheric particulate matters (APMs)

Summary

Introduction

Lung cancer remains the most prevalent cancer (11.6% of all cases) and the leading cause of cancer deaths worldwide (18.4% of all cancer deaths) [1]. The mortality of lung cancer in Xuanwei’s rural areas are 27.7/100,000 for men and 25.3/100,000 for women, almost five times that of China’s national average (4.97/100,000 for both sexes) [4], it ranks among the top in the world for female lung cancer mortality [5]. The etiology of lung cancer in the region remains unclear and known or suspected risk factors such as tobacco [6], potentially toxic metals [7,8,9], PAHs [10], and SiO2 [11,12] may account for only a small fraction of lung cancer cases, necessitating further study

Methods

Results

Conclusion