According to international guidelines, “bioaccumulation” is defined as the process where the chemical concentration in an aquatic organism achieves a level that exceeds that in the water as a result of chemical uptake through all routes of chemical exposure (e.g. dietary absorption, transport across the respiratory surface, dermal absorption). Bioaccumulation typically takes place under field conditions and is a combination of chemical bioconcentration and biomagnification (the process by which lipid normalized chemical concentrations increase with trophic level in a food-chain). The extent of chemical bioaccumulation is usually expressed in the form of a bioaccumulation factor (BAF), which is the ratio of the chemical concentration in the organism (CB) and the water (CW), including the uptake in the diet.
Source: CAESAR project