The scope of this Interest Group (IG) is quantitative models to describe the behavior and exposure pathways of chemical, biological and physical contaminants in the environment and for human and ecological populations. Examples include, but are not limited to, models of source-to-concentration relationships in defined systems, models to estimate overall persistence and long-range transport potential of contaminants, models of bioaccumulation of contaminants by individual organisms or in food webs, models of human exposure to chemicals, biological agents or nanomaterials by multiple pathways, and pharmacokinetic models of the distribution of chemicals, biological agents and nanomaterials in the bodies of exposed humans or animals. The IG will also focus on development of a data to support the application of models including physical properties and degradation rates, emissions inventories, and monitoring or exposure concentration data for environmental media (air, water, soil, sediments and vegetation) and biota.