The bioaccumulation of chemicals in organisms beyond the concentration expected if the chemical was in equilibrium between the organism and its surroundings. Biomagnification can occur in both terrestrial and aquatic environments, but it is generally used in relation to aquatic situations. Most often, biomagnification occurs in the higher trophic levels of the food chain/web, where exposure to chemicals takes place mostly through food consumption rather than water uptake.

Biomagnification is a specific case of bioaccumulation and is different from bioconcentration. Bioaccumulation describes the accumulation of contaminants in the tissue of organisms. Typical examples of this include the elevated levels of many chlorinated pesticides and mercury in fish tissue. Bioconcentration is used to describe the concentration of a chemical in an organism from water uptake alone. This is quantitatively described by the bioconcentration factor, or BCF, which is the chemical concentration in tissue divided by the chemical concentration...