Bioaccumulation factor definition

To indicate the transfer of chemicals in a biogeochemical food web, both bioaccumulation factors (BAFs) and bioconcentration factors (BCFs) are used. The following definitions can be applied (de Vries and Bakker, 1998a, 1998b) ... 

The term bioaccumulation factor (BAF) is a coefficient used to quantify the net body burden of chemicals (given uptake, distribution, metabolism, and excretion rates) and is expressed as the ratio of the concentration of a compound in the organism (or normalized to the lipid weight of the organism) to the concentration in its food or, for benthic or soil invertebrates, in the sediment or soil [9] (also see Chapter 6). Although by definition, BAF is measured at steady state, due to the complex nature of multiplepathway exposure, steady-state measures of BAF are often difficult to obtain. 

Fig. 16. Bioaccumulation factor (normalized to organism lipid and sediment organic carbon) as a function number of aromatic rings in PAHs. Mean and standard error of the mean BAFi c for PAHs consists of 2-6 aromatic rings. Each mean represents several PAHs and sediments (sites = 7 for amphipod = 5 for polychaete). [See Table 1 for PAHs and ring categories.] Polychaete (Armandia brevis) and amphipod (Rhepoxynius abronius) individuals were exposed to Raritan-Hudson estuary (New York) sediments for 10 d. See Appendix for BAFioc definition. (Data from Meador et al. 1995.)...

Chemicals, which are persistent, toxic and liable to bioaccumulation, are called PTBs. They have primarily local effects. Persistence is the evidence that the substances half-life is greater than two months in water and greater than sue months in soil or sediment. Toxicity is the potential to adversely affect human health and/or the environment. Bioaccumulation is the evidence that the Bio-Accumulation Factor (BAF) is greater than 5000. Up to 1995, there was no clear definition of which products belong to this class [394]. Heavy metals, such as mercury and POPs fall into this category. 

---