Abstract
Fly ash produced during coal combustion is one of the major sources of air and water pollution, but the data on the impact of micrometer-size fly ash particles on human cells is still incomplete. Fly ash samples were collected from several electric power stations in the United States (Rockdale, TX; Dolet Hill, Mansfield, LA; Rockport, IN; Muskogee, OK) and from a metallurgic plant located in the Russian Federation (Chelyabinsk Electro-Metallurgical Works OJSC). The particles were characterized using dynamic light scattering, atomic force, and hyperspectral microscopy. According to chemical composition, the fly ash studied was ferro-alumino-silicate mineral containing substantial quantities of Ca, Mg, and a negligible concentration of K, Na, Mn, and Sr. The toxicity of the fly ash microparticles was assessed in vitro using HeLa cells (human cervical cancer cells) and Jurkat cells (immortalized human T lymphocytes). Incubation of cells with different concentrations of fly ash resulted in a dose-dependent decrease in cell viability for all fly ash variants. The most prominent cytotoxic effect in HeLa cells was produced by the ash particles from Rockdale, while the least was produced by the fly ash from Chelyabinsk. In Jurkat cells, the lowest toxicity was observed for fly ash collected from Rockport, Dolet Hill and Muscogee plants. The fly ash from Rockdale and Chelyabinsk induced DNA damage in HeLa cells, as revealed by the single cell electrophoresis, and disrupted the normal nuclear morphology. The interaction of fly ash microparticles of different origins with cells was visualized using dark-field microscopy and hyperspectral imaging. The size of ash particles appeared to be an important determinant of their toxicity, and the smallest fly ash particles from Chelyabinsk turned out to be the most cytotoxic to Jukart cells and the most genotoxic to HeLa cells.
Highlights
Coal-consuming industries are among the main sources of air pollution with fly ash [1,2,3]
The Chelyabinsk fly ash sample was more toxic than other fly ash samples when studied We found that the fly ash from Rockport and Muskogee was more associated with in Jurkat cells, while this effect was not observed in human cervical carcinoma (HeLa) cells
Chelyabinsk fly ash sample was more toxic than other fly ash samples when studied suggesting that toxic effects resulted from the complex combination of different fly ash in effect was not observed cells
Summary
Coal-consuming industries are among the main sources of air pollution with fly ash [1,2,3]. In addition to the direct negative effect of airborne fly ash solid particles at the place of origin, a significant danger lies in their transportation with air currents over long distances. In 2015, the EPA published a Coal Combustion Residuals (CCR) regulation, which, still classifying coal fly ash as non-hazardous, places new restrictions on landfills and surface impoundments as an attempt to prevent the leaking of toxic metals to groundwater [18]. We analyzed the alumosilicate fly ash microparticles collected from several electric power stations and a metallurgic plant and assessed their toxicity in vitro using the HeLa cells (human cervical cancer cells) and Jurkat cells (immortalized human T lymphocytes), typical models in numerous cell culture-based experiments. The cytotoxicity and genotoxicity of the investigated solid particles were evaluated as moderate at concentrations below 10 mg/mL (i.e., for ponds, it is ≈10,000 g/m3 ) and it was higher for fly ash particles sized less than 1 μm and concentration of 20 mg/mL
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