Nitroaromatic Compounds: Environmental Pollutants with Carcinogenic Potential for Humans

Abstract

Nitroaromatic compounds, ubiquitous in nature, are potent mutagens and carcinogens for humans. Exposure to nitroaromatic compounds occurs in a variety of ways. Polycyclic aromatic hydrocarbons react with nitrogen oxides to form nitroaromatics under the conditions that might be expected in polluted air and in combustion processes. As a result, nitroaromatic compounds are present in many mixtures such as cigarette smoke, fly ash and diesel exhaust. One or more nitro groups in aromatics profoundly influence their binding to DNA, and thus their carcinogenic potential. For most compounds, reduction of nitro groups plays a major role in mutagenesis and carcinogenesis, while the role of ring hydroxylation seems to be mainly detoxification or it is still unclear. This review describes details concerning carcinogenicity of 2-nitroanisole, the mechanism of which has not yet been explained. This compound continues to pose a threat to human health in the contaminated area in Germany due to an accident in the Hoechst company in 1993. Therefore, future studies should employ specific metabolites and DNA adducts as markers for risk assessment, which will provide useful data for epidemiological studies. Specific 2-nitroanisole metabolites were found and a novel method for sensitive detection of adducts of DNA and 2-nitroanisole in vivo was developed.