Pollution levels and health risk assessment of potentially toxic metals of size-segregated particulate matter in rural residential areas of high lung cancer incidence in Fuyuan, China.

The highest incidence and mortality rate of lung cancer in rural area of Fuyuan has been a research hotspot, and the pathogenesis is still unclear. Therefore, atmospheric particulate matters (APMs) samples were collected between 18 February and 01 March 2017, exploring water-soluble potentially toxic metals (WSPTMs) and water-soluble inorganic ionic species (WSIIs) levels, size distribution, sources, acidity and alkalinity, and potential carcinogenic and non-carcinogenic risks, hoping to provide scientific basic data to solve this problem. In our study, the average ratio of nitrate ion (NO 3 - )/sulfate ion (SO 4 2- ) within PM 1.1 , PM 1.1-2.0 , PM 2.0-3.3 , PM 3.3-7.0 , and PM >7.0 were 0.22, 0.18, 0.15, 0.34 and 0.36, respectively, that revealed that combustion sources contributed to PM were more significant. The anions in equilibrium (ANE) / cations in equilibrium (CAE) < 1 for all samples within PM 1.1 , PM 2.0-3.3 , PM 3.3-7.0 indicate that the APMs were alkaline, but PM 1.1-2.0 particulate matter shows weak acidity. SO 4 2-  prefers to combine with NH 4 +  to form (NH 4 ) 2 SO 4 , which hinders the formation of NH 4 NO 3 , the remaining SO 4 2-  and NO 3 - to neutralize the K + , KNO 3  was formed at all particulate, however, K 2 SO 4 can only be formed in PM <3.3 . Arsenic (As) and Selenium (Se) were identified as the most enriched WSPTMs in all PM sizes, predominantly from anthropogenic emissions, were suggested that coal combustion is a significant source of PM-bound WSPTMs. Total WSPTMs exhibited high total carcinogenic risks (TCR) values (9.98 × 10 -6 , 1.06 × 10 -5 , and 1.19 × 10 -5 for girls, boys and adults, respectively) in the smaller particles (< 1.1 μm). Se was considered as the major contributor (63.60%) to carcinogenic risk (CR) in PM 2.0 and had an inverse relationship with PM size that should be of prime concern.