Estimating biotransformation rate constants of organic chemicals from modeled and measured elimination rates

In this study, biotransformation rate constants are estimated for a large s et of organic compounds. Biotransformation (k(m)) is considered part of the total elimination, further consisting of physico-chemical elimination to w ater (k(w)), depuration by feces (k(f)) and growth dilution (gamma). Existi ng models are used to estimate k(w) and k(f), and gamma. The difference bet ween measured elimination rate constants and the sum of predicted eliminati on rate constants for water, feces and growth indicates the ration of biotr ansformation in the total elimination. In all examined animal classes, polycyclic aromatic hydrocarbons seem to be metabolized at an intermediate rate. Because of the relative low hydrophob icity of some of the studied compounds, their physico-chemical elimination rate constant is relatively high, and the relative contribution of metaboli sm to total elimination of these compounds is therefore relatively low. Fis h seem to be capable of metabolizing chlorodibenzo-p-dioxins and -furans, D DT, chloroanilines and phenol. (C) 2001 Elsevier Science Ltd. All rights re served.