A free-radical model for the toxic action of halogenated molecules with two critical parameters, namely, (1) the ability of the halogenated hydrocarbon to produce free radicals by dissociative electron attachment and (2) the ability of the so-produced free radical to abstract a hydrogen atom from the cellular material, is tested using experimental data on halogenated methanes. (c) 2005 Elsevier B.V. All rights reserved.