Health risks of chromium from disposed ash of coal-burning power plants

Abstract

Coal is expected to play an important role in meeting energy needs of the European Community (EC) in the coming decades. This will result in an increased release of trace metals to the environment. In particular, improvement of air pollution control technique of coal-fired power plants used for the retainment of particulate matter will reduce trace metal emissions from the stack but on the other hand will increase substantially trace metal concentrations of the solid residues of coal combustion such as precipitator fly ash. Most of this fly ash normally is disposed in some way, e.g. in landfills or used for amendement of agricultural soils. So water leaching of trace metals from disposed fly ash could be an important pathways of certain trace metals to water bodies with a potential impact on terrestrial and aquatic environments as well as human health. Assessment of these impacts can be conveniently studied by using mathematical dynamic models and system analysis. This work assess the long term migration of chromium from a fly ash repository to man via food chain evaluating the toxicological risk to humans. In particular, the use of an environmental model allows the evaluation of the long term impact of chromium to agricultural soil after its percolation to groundwater as well as to agricultural products for man's diet. Water leaching laboratory experiments supplied key data such as the leaching rate to the model. The application of human dose models made if possible to predict the distribution of chromium in human tissues and to assess the associated health risk. This latter was compared with the estimated risks from other sources. The results show that (i) Cr from disposed ash can significantly increase the normal dietary intake of the element to man, on condition that he is living ne nearest the fly ash deposit (ii) the health risks from leached chromium to population will become negligible at a distance of about 20 – 30 Km from the fly ash repository.