Internal Effect Concentration: Link Between Bioaccumulation and Ecotoxicity for Organic Chemicals

Abstract

This paper reviews the concept and the use of internal effect concentrations. Bioaccumulation plays a very important role in this concept, and is part of the process which results in that chemicals attain body burdens and eventually internal effect concentrations in an organism which cause adverse effects. Hydrophobic compounds elicit their toxicity at low external concentrations because their high bioaccumulation properties allow critical or lethal body burdens in organisms to be reached already at those low environmental ambient concentrations. First, a concise overview is provided of bioaccumulation models, bioaccumulation parameters, and factors which influence bioaccumulation of organic chemicals for aquatic, benthic and terrestrial organisms. Second, a brief overview is given on external and internal effect concentrations. The concept and assumptions related to the internal effect concentrations are dealt with in more detail. Third, bioaccumulation and effects are linked through the concept of internal effect concentration. Bioaccumulation kinetics can be used to describe and predict concentrations of organic compounds in an organism. Established relationships can be used for this purpose, which include physical-chemical and physiological parameters, in addition to ambient concentrations in the environment, such as in water, sediment and soil, and in food. The use of predicted concentrations and internal effect concentrations of organic compounds enables one to evaluate ecotoxicological risk for these compounds. Since the internal concentration adds all molar concentrations of individual chemicals as one molar concentration, the internal concentration thus deals with additivity of a mixture. Biomimetic extraction and molar detection techniques are discussed and suggested to offer a useful tool to assess the total amount of bioaccumulatable organic compounds.