Modelling the bioconcentration of hydrophobic organic chemicals in aquatic organisms

By incorporating organism growth into the bioconcentration process for hydrophobic organic chemicals (HOCs) in aquatic organisms, a set of equations is proposed to express the time course for uptake of HOCs by the organism. The Boltzman equation, which produces sigmoidal curve and is somewhat similar to the logistic growth equation, is used to describe organism or population growth. The effect of metabolism can be included, if desired. With the proposed model, values of uptake and elimination rate constants, k1 and k2, and thereafter the bioconcentration factor, BCF, can be obtained, depending only on the time course for uptake of HOCs by the organism. The set of equations is tested by using some published data for the time course of HOC uptake by aquatic organisms. The agreement of our values for k1, k2 and BCF with those in the literature is excellent. Various features of the proposed model are discussed.