Ecotoxicity of polycyclic aromatic hydrocarbons, aromatic amines, and nitroarenes through molecular properties

Abstract

Air, marine, and terrestrial pollution are continuously critical issues to be solved in environmental sciences. Particularly with the recent disaster in the Mexico Gulf and the risk of oil spills from the continuous offshore drilling activities in the North Sea, ecotoxicological profiling requires great attention. Fjord ecosystems are particularly neglected marine ecosystems, which require better surveillance and ecotoxicological profiling. In this context, this study focuses on exploring three potential indicators for aquatic stress [polycyclic aromatic hydrocarbons (PAHs), aromatic amines (AAs), and nitroarenes (NAs)] by the study of their molecular and sub-molecular properties. The results show that the aromatic amine, 4-aminobiphenyl, gains a particularly reactive electronic potential, which can be summarized as a large change in LUMO+2 and HOMO−1 electron orbitals upon metabolic activation in the organism. This change in orbitals increases the overall electrostatic energy of the molecule, inducing a high affinity for DNA-adduct formation. Electronic analysis on nitroarenes shows in addition why 1,6-dinitropyrene is more stable than 1,8-dinitropyrene, and how the electrons favor nitrenium activation on the 6th and 8th carbon. Further analysis shows also that PAHs have a present correlation with hormonal similarity, and that their resemblance to estrogen can be correlated to mutagenicity, contributing to increased ecotoxicity. The electronic analysis of these three types of fossil pollutants shows how their toxicity is exerted from the electronic level and which structural features that determine the level of reactivity and toxicity. The summation of the background and electronic properties of these molecular toxins elucidates that PAHs, aromatic amines, and nitroarenes are all of equal importance as stress indicators for fjord systems, with particular emphasis on PAHs, which also exert hormonal structural similarities as a probable base of their carcinogenic mechanisms.