Toxicokinetic modeling of mixtures of organic chemicals

A residue-based one-compartment, first-order-kinetics model (1CFOK) was used to investigate the toxicity of mixtures of organic chemicals to the American flagfish, Jordanella floridae. Four sets of chemicals (chloroethanes, chloroethylenes, chlorobenzenes, and chlorophenols) were used to examine within-set mixtures. Component chemicals of the mixtures appeared to be simply additive at threshold LC50. Kinetics rate constants and critical body residue (CBR) data estimated from single chemical toxicity test data, along with bioconcentration factor information calculated from log Kow, were used to model the time course of toxicant action of the mixtures and compare them against independently observed mixture toxicity test results. Agreement between observed and modeled information was good, in terms of both threshold toxicity estimates and the time course of toxicant action.