This chapter will provide guidance on how to estimate environmental exposure. More specifically, it will deal with: Estimation of the releases to air, water (either wastewater and/or surface water), and soil at local and regional scale.Fate and distribution of the releases in environmental compartments (air, soil, surface water, sediment, biota) and sewage treatment plants. Calculation of exposure concentrations in / doses for, respectively: Environmental compartments (Section R.16.6.1), in terms of Predicted Environmental Concentrations (PECs), at both local and regional scales, covering both direct exposure of organisms and exposure via the food chain for predators. Man via the environment (Section R.16.6.8) in terms of human daily intake of the substance through drinking water, fish, leaf crops, root crops, meat and dairy products, at local and regional scale. Most of the current guidance on environmental exposure estimation has been developed mainly for organic substances. Metals and metal compounds present particularities (natural background and historical releases, speciation, adsorption/desorption behaviour, differences in bioavailability) which require specific adaptations when performing the exposure assessment. These issues are considered in the Appendix R.7.13-2.