Biomedically relevant chemical and physical properties of coal combustion products.

Abstract

The evaluation of the potential public and occupational health hazards of developing and existing combustion processes requires a detailed understanding of the physical and chemical properties of effluents available for human and environmental exposures. These processes produce complex mixtures of gases and aerosols which may interact synergistically or antagonistically with biological systems. Because of the physicochemical complexity of the effluents, the biomedically relevant properties of these materials must be carefully assessed. Subsequent to release from combustion sources, environmental interactions further complicate assessment of the toxicity of combustion products. This report provides an overview of the biomedically relevant physical and chemical properties of coal fly ash. Coal fly ash is presented as a model complex mixture for health and safety evaluation of combustion processes.

Consensus report: mutagenicity and carcinogenicity of car exhausts and coal combustion emissions

“…Earlier studies of gasoline emissions coupled chemical characterization with rodent tumorigenesis studies (43). These studies show that the PAH may be the major class of chemicals contributing to rodent tumori- (50). The supermicron mode (> 5 pum) generally reflects mineral agglomeration; the micron mode (1-2 ,um) is the result from the size distribution of the clay minerals associated with coal; and the submicron mode (< 0.5 ,um) is the result of both gaseous cursting of aluminosilicate and homogeneous gas phase nucleation with subsequent agglomeration.…”

“…All the generally accepted or strongly suspected human metal carcinogens (As, Ni, Cr, Cd, Be) are present in coal and are released to a certain degree with the flue gas (50,52,53). Most studies indicate that the most volatile elements (or their oxides), Cd, Zn, Se, As, Sb, W, Mo, Ga, Pb and V, display the greatest concentration dependence on particle size due to condensation on fly ash surfaces.…”

“…The total emissions of organic substances from coal fired boilers are dependent on the combustion efficiency. Large power plants fired with pulverized coal generally have efficient combustion and emit very small amounts of organic compounds whereas smaller boilers are often less efficient and produce greater concentrations or organic effluents (50). A variety of PAH has been identified in emissions from coal combustion, particularly under suboptimal combustion conditions.…”

Role of inhalation studies with animals in defining human health risks for vehicle and power plant emissions.

“…Unfortunately, from an experimental viewpoint fly ash is not a single material but will vary in its physical and chemical characteristics dependent upon factors such as the fuel and combustion process (25,26). The limited data available on retention of inhaled fly ash in rodents may not adequately predict the retention of all kinds of fly ash.…”

“…Interest in the fate of specific chemical constituents associated with particles is increased by recognition that different solvents can remove mutagenic chemicals from both fly ash and diesel exhaust soot particles (26,(29)(30)(31). Some of the mutagenic activity associated with fly ash may be attributed to inorganic compounds.…”