EU Science Hub

Aquatic Bioconcentration/Bioaccumulation

Information on accumulation in aquatic organisms is important for understanding the behaviour of a chemical in the environment. This information is used for hazard classification and Persistence, Bioaccumulation and Toxicity (PBT) assessment.

Bioconcentration describes the accumulation of a water-borne chemical by an aquatic organism, whereas bioaccumulation covers the uptake from all environmental sources, e.g. water, food and sediment.

The bioconcentration potential of a chemical, expressed as the 'BCF', is either predicted or measured. The BCF describes the ratio of the concentration of a chemical in the whole organism to its concentration in the water, under equilibrium conditions.

Fish is the preferred species for bioconcentration/bioaccumulation testing and derivation of a BCF, although data from tests using invertebrates or reliable BCF prediction models can be used.

Experimental determination of bioconcentration/bioaccumulation may not be necessary if it can be demonstrated that a chemical has a low potential to bioaccumulate, by using physicochemical properties (e.g. log KOW < 3) or other evidence.

Since bioaccumulation is the result of absorption, distribution, metabolism and excretion (ADME) processes, information on ADME processes derived with in vitro methods is used to improve the prediction of BCF models, in particular information on metabolism.

The EURL ECVAM Strategy to replace, reduce and refine the use of fish in aquatic toxicity and bioaccumulation testing (published in 2014) provides an overview of ongoing projects.

Regulatory framework

Alternative test methods under validation by EURL ECVAM

Development and optimisation of alternative methods