We recently constructed a Chinese hamster V79-derived cell line that stably expresses human cytochrome P450 (CYP) 2E1 and human sulphotransferase (SULT) 1A1. These enzymes are involved in the bioactivation of numerous promutagens/procarcinogens, but are not taken into account in standard in vitro mutagenicity assays. Various carbohydrate pyrolysis products and other food contaminants that induce tumours or preneoplastic lesions in laboratory animals are inactive or only weakly active in standard in vitro genotoxicity assays. This is the case for acrylamide, furan, 5-hydroxymethylfurfural, nitrofen and N-nitrosodimethylamine. These compounds were investigated for induction of sister chromatid exchange (SCE) in V79-hCYP2E1-hSULT1A1 cells. All test compounds showed positive results over a wide concentration range, starting at 0.01 microM for N-nitrosodimethylamine, 3 microM for furan, 12.5 microM for nitrofen, 20 microM for 5-hydroxymethylfurfural, and 200 microM for acrylamide. The concentration-response curve of furan was unusual, as this compound induced a statistically significant, but rather constant and weak increase in SCE over an extremely wide concentration range (3-16,000 microM). Furan was slightly less active, whereas the remaining compounds were much less active in the parental V79 cell line than in V79-hCYP2E1-hSULT1A1 cells. Compared to many other genotoxic effects, the study of SCE only requires small numbers of cells (and incubation volumes) and usually is detected even at low concentrations of the genotoxicant. Therefore, induction of SCE in V79-hCYP2E1-hSULT1A1 cells may be useful in the genotoxicity testing of preparations of heated food and in their bioassay-directed fractionation.