Evaluating the environmental fate of a variety of types of chemicals using the EQC model

Abstract The multimedia equilibrium criterion model, which can be used to evaluate the environmental fate of a variety of chemicals, is described. The model treats chemicals that fall into three categories. In the first the chemicals may partition into all environmental media, in the second they are involatile, and in the third they are insoluble in water. The structure of the model, the process equations, and the required input data for each chemical type are described. By undertaking a sequence of level I, II, and III calculations, increasing information is obtained about the chemical's partitioning, its susceptibility to transformation and transport, and the environmental process and the chemical characteristics that most influence chemical fate. Output data, consisting of tables and charts, give a complete picture of the chemical's fate in an evaluative or generic environment. The model is illustrated by applying it to two chemicals, pyrene, which is a chemical of the first type, and lead, which is of a second type. The role of this model as a tool for assessing the fate of new and existing chemicals is discussed.