Trichloroethylene. III. Prediction of carcinogenicity of investigated compounds including trichloroethylene.

The mutagenicity and carcinogenic properties of trichloroethylene (TCE) derivatives, and their correlation with its molecular properties were analyzed. The observed cancer incidence was compared to the predicted, calculated incidence. The predictions were based on the rodent bioassay results and were consistent with human data. The electrophilic data of molecules of the Ke system provided evidence for 205 rodent carcinogens, where Ke correlated with energy of the lowest unoccupied molecular orbital. The majority of carcinogenic compounds were found to be electron acceptors with decreased lowest unoccupied molecular orbital (LUMO) energy, indicating the particular DNA-reactivity leading to mutations and abnormal cell division. Based on the mutagenic activity in Ames test, the affinity of target organs for mutagens and non mutagens were compared in 351 rodent carcinogens. Nearly 80% of carcinogens (mutagenic and non mutagenic ones) were positive in the mouse and rat, in at least one of the most frequent target organs, i.e. liver, lung, mammary gland, stomach, kidney, hematopoietic system, urinary bladder and vascular system. Several predictive methods have been developed over the last 5 years based on structure-activity relationship studies known as US National Toxicology Program. One of these programs, called "PROGOL" is widely used for the prediction of carcinogenesis for a wide variety of compounds, e.g., nitro aromatics and suramin analogs. This program provides a simple model for predictive carcinogenesis, despite of the fact that the very first steps of carcinogenesis are not fully understood yet.