ABSTRACT
This chapter describes the word “medium” is reserved to indicate the major environmental compartments: air, water, sediment, and soil. The word “matrix” is associated with the physicochemical properties of the media. The extrapolation issues dealing with matrix and media can thus be divided into exposure issues and effects issues. The exposure to and fate of any toxicant are governed by the interaction between the matrix components and the toxic chemical. In matrix extrapolation, and with emphasis on the pore water exposure route, it is therefore of great practical importance to have a quantitative understanding of the distribution of heavy metals over the solid phase and the pore water. Extrapolating toxicant effects among media may differ according to the trophic status of the species under consideration. Feeding behavior is one of the most important variables that should be taken into account when extrapolating among media. There are few specific extrapolation methods that attempt to extrapolate species sensitivities across media and matrices.
