Mutagenicity Of Exhaust Research Articles

Toxicity and mutagenicity of exhaust from compressed natural gas: Could this be a clean solution for megacities with mixed-traffic conditions?

Despite intensive research carried out on particulates, correlation between engine-out particulate emissions and adverse health effects is not well understood yet. Particulate emissions hold enormous significance for mega-cities like Delhi that have immense traffic diversity. Entire public transportation system involving taxis, three-wheelers, and buses has been switched from conventional liquid fuels to compressed natural gas (CNG) in the Mega-city of Delhi. In this study, the particulate characterization was carried out on variety of engines including three diesel engines complying with Euro-II, Euro-III and Euro-IV emission norms, one Euro-II gasoline engine and one Euro-IV CNG engine. Physical, chemical and biological characterizations of particulates were performed to assess the particulate toxicity. The mutagenic potential of particulate samples was investigated at different concentrations using two different Salmonella strains, TA98 and TA100 in presence and absence of liver S9 metabolic enzyme fraction. Particulates emitted from diesel and gasoline engines showed higher mutagenicity, while those from CNG engine showed negligible mutagenicity compared to other test fuels and engine configurations. Polycyclic aromatic hydrocarbons (PAHs) adsorbed onto CNG engine particulates were also relatively fewer compared to those from equivalent diesel and gasoline engines. Taken together, our findings indicate that CNG is comparatively safer fuel compared to diesel and gasoline and can offer a cleaner transport energy solution for mega-cities with mixed-traffic conditions, especially in developing countries.

The effect of fuel composition on the mutagenicity of diesel engine exhaust

The effect of fuel composition on the mutagenicity of diesel engine emission was investigated. To this end, a fuel matrix comprising fuels with different contents of aromatic and naphthenic compounds was used. Extracts of the organic phase of raw exhausts obtained with different fuels were tested for mutagenicity in bacterial reversion assays. The results obtained demonstrate that the mutagenicity of diesel exhaust is largely dependent on the aromatic content of the fuel. In fact, mutagenicity was greatly reduced when the aromatic content of the fuel was lowered by hydrogen treatment. Conversely, mutagenicity was enhanced when the fuel was enriched with fractions of di- or triaromatic compounds. The addition of di- and trinaphthenic compounds only produced borderline mutagenicity. No clear relationship was observed between sulfur content of the fuel and mutagenicity of the exhaust. Assays in bacterial strains with different sensitivity to nitroaromatic compounds suggest a low contribution of the highly mutagenic dinitropyrenes to the responses observed, and a relatively greater contribution of 1-nitropyrene or other nitroaromatics processed by the same bacterial nitroreductase.