PM2.5-bound trace metal compositions in the vicinity of a coal-fired power plant in Klang, Malaysia, their potential sources, human health risks and toxicity towards V79 cells

Abstract

Industrial activities led to environmental degradation that could increase health risk to the nearby residents. A mixed residential and industrial area having a coal-fired power plant could be environmentally taxing. A study was conducted in Klang to determine PM2.5 concentrations, its trace metal compositions, sources, and assess their health risks. It also aims to assess the cytotoxic effect and oxidative stress induced from exposure to PM2.5-bound trace metal extracts. PM2.5 samples were collected within the vicinity of the coal-fired power plant using HVS from June to November 2018. Trace metals were extracted from the filters via sonication in ultrapure water and analysed for 18 element concentrations through ICP-MS. Principal component analysis (PCA) was conducted to identify sources of trace metals in PM2.5. Hazard quotients (HQ) were estimated for Al, As, Cd, Co, Cr, Mn, Ni, and V while incremental lifetime cancer risks (ILCR) were estimated for As, Cd, Co, Ni, and Pb. PM2.5-bound trace metal extracts was exposed to V79 cells to evaluate for viability (MTT assay) and oxidative stress (hydroethidine assay). Results showed that mean concentration of PM2.5 during southwest (June – September), inter- (October) and northwest (November) monsoons were 14.54 ± 10.09 μgm-3 (range 0.76–43.15 μgm-3), 11.05 ± 5.11 μgm-3 (range 7.44–14.67 μgm-3), and 16.41 ± 3.25 μgm-3 (range 14.11–18.71 μgm-3) respectively. 24-Hour mean for PM2.5 concentrations were below the Malaysian national standard of 35 μgm-3 (MAAQS), except for one sample in September (43.15 μgm-3). PCA identified four factors and predicted the sources of PM2.5 as mixture of biomass burning and sea sprays (37%), mixture of coal combustion and vehicular emissions (34%), oil combustion (17%) and soil dust (12%). Health risks from exposure to PM2.5 were found negligible. No significant cytotoxic effect was observed from exposure of PM2.5-bound trace metal extracts towards V79 cells. However, a slight oxidative stress was observed via hydroethidine assay. We found that while power plant was one of the major contributors of PM2.5, there are other significant regional sources including transboundary sources from neighbouring country. Maintaining low PM2.5 concentration would be vital in minimising the health risks of residents from nearby industrial or commercial activities towards achieving United Nations’ SDG Agenda 2030.