Glucosinolates are compounds produced by commercial crops which can hydrolyse in a range of natural toxins that may exert detrimental effects on beneficial soil organisms. This study examined the effects of 2-phenylethyl isothiocyanate and 3-phenylpropionitrile on the survival and growth of the woodlouse Porcellio scaber exposed for 28d. 2-Phenylethyl isothiocyanate dissipated from the soil with half-lives ranging from 19 to 96h. Exposure through soil showed toxic effects only on survival. The LC50s after 28d were significantly different at 65.3mgkg(-1) for 2-phenylethyl isothiocyanate and 155mgkg(-1) for 3-phenylpropionitrile. A toxicokinetic-toxicodynamic (TKTD) approach, however, revealed that both compounds in fact have very similar effect patterns. The TKTD model was better suited to interpret the survival data than descriptive dose-response analysis (LC(x)), accounting for the fast dissipation of the compounds in the soil. Found effects were within environmentally relevant concentrations. Care should therefore be taken before allowing these natural toxins to enter soil ecosystems in large quantities.