The 'B' in PBT: Bioaccumulation

Bioaccumulation results in concentrations of substances in organisms that are much higher than the concentrations in their surrounding medium or food. Contaminants that accumulate through the foodchain must be (1) taken up, (2) persistent against biotransformation, and (3) excreted at a very slow rate. Most of the existing knowledge on bioaccumulation is based on studies on organic substances in aquatic species, on predators who prey on aquatic species, on terrestrial plants, and on the subsequent foodchain. The physical-chemical parameter which is often used as a surrogate for the bioaccumulation potential of organic substances from water and food is the octanol/water partition coefficient (Kow), while that for the route via air is the octanol/air partition coefficient (Koa). For metals or other non-organic substances, that strongly bioaccumulate, no surrogate physical-chemical parameters are known.