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

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.

Characteristics of Environmentally Persistent Free Radicals in PM2.5 and the Influence of Air Pollutants in Shihezi, Northwestern China

“…However, the chemical constituents can vary considerably depending on the emission source [ 30 ]. It should be noted that a larger ΔHp-p value indicates a lack of hyperfine split structures [ 31 ], implying the existence of several organic free radicals in PM 2.5 .…”

Toxicity Decreases with the Decay of Environmentally Persistent Free Radicals in Particulate Matter from Incomplete Solid Fuel Burning

“…Each fuel/stove combination was repeated at least 3 times for quality assurance. Detailed information is provided in Text S1 and available in our previous studies. , The collected PM 2.5 samples were saved for further analysis of EPFRs, which were reported to be concentrated in the particulate phase. , …”

“…29,30 The collected PM 2.5 samples were saved for further analysis of EPFRs, which were reported to be concentrated in the particulate phase. 31,32 Decay Study of PM Samples. The collected PM 2.5 samples were characterized in the following three cases (named three groups), as displayed in Figure S2.…”

Physicochemical Characterization and Oxidative Potential of Iron-Containing Particles Emitted from Xuanwei Coal Combustion

“…The relevant parameters were as follows: sweep time, 120 s; center field, 324.74 mT; sweep width, 25 mT; modulation frequency, 100 kHz; modulation width, 0.05 mT; microwave frequency, 9105.26 MHz; and microwave power, 0.998 mW. More information can be found in our previous work [5]. For •OH radical detection, 10.0 mmol/L sodium benzoate (NaBA) was employed as a prober to measure •OH radicals.…”

“…However, the etiology of lung cancer in the region remains unclear. Several risk factors, such as toxic metals [4,5], polycyclic aromatic hydrocarbons (PAHs) [6], and nano crystal SiO 2 [3,4] have been reported to have relationship with the development of lung cancer in Xuanwei residents. More recently, researchers believed that the high content of nano mineral particles emitted during coal combustion might contribute to the high incidence rate of lung cancer [7], and nanosized particles were also found in the pulmonary and normal tissues of lung cancer patients using TEM-EDX [8].…”