The assessment of the carcinogenic potential of polycyclic aromatic hydrocarbons (PAH) is obtained by a principal component analysis (PCA) and quantitative structure-activity relationship (QSAR) using hydrophobic (LogP), stereo and electronic parameters (electron affinity, dipole moment and HOMO-LUMO gap) calculated from the AM1 method. The PAH-DNA interaction model is based on the unsynchronized resonating valence bond theory (RVB) developed by L. Pauling. The QSAR study reproduces the experimental values of LD50 in rats with 95% confidence. The PCA analysis classify all the selected compounds as potential carcinogens, an important result since many of these PAH are not classified as carcinogens, indicating the need for an urgent revision of its classification.

The carcinogenic potential of carbendazim and its metabolites was analyzed using statistical treatment of electronic parameters obtained from DFT/ 6-311++G(d,p) and AM1 calculations. The carcinogen-DNA interaction is described in the framework of the theory of unsynchronized resonance of covalent bond as a process of electron transfer involving the HOMO and LUMO frontier orbitals. Through a Principal Component Analysis (PCA) of the electron affinity, carcinogen-DNA interaction energy, electrostatic attraction and cell membrane permeability (dipole moment m and partition coefficient LogP) evidence was obtained showing carbendazim displays carcinogenic activity. For the metabolites of carbendazim, no evidence was found in the literature of their carcinogenic activities. However, the electronic parameters for these metabolites exhibited similarity to known carcinogens, thereby showing the importance of the results obtained in this study for a policy based on the precautionary principle.