Influence of ethanol and methanol gasoline blends on the mutagenicity of particulate exhaust extracts.

TheSalmonella mutagenicity test was used to evaluate the influence of alcohol fuel extenders on the genetic toxicity of particulate exhaust extracts. Four spark-ignition engine equipped vehicles were operated on gasoline alone, 10% blends of ethanol or methanol in gasoline, and a commercially available “gasohol.” The tests were conducted on a chassis dynomometer and the particulate exhaust was collected on high volume filters after dilution in a tunnel. The vehicles used were a 1980 Chevrolet Citation, a 1980 Mercury Monarch, a 1981 Ford Escort and a 1981 Oldsmobile Cutlass. Dichloromethane extracts of the exhaust particles from all tests were mutagenic inSalmonella typhimurium strains TA 100 and TA 98. The extracts were less mutagenic in the nitroreductase deficient strains TA 98NR and TA 98DNPR suggesting that nitro substituted polycyclic aromatic hydrocarbons may be responsible for part of the mutagenicity. In all the alcohol blended fuel tests, the mass of particle associated organics emitted from the exhaust was lower than that observed during the control tests using gasoline alone. Thus, in most cases, estimates of the emission of mutagenic combustion products from the exhaust were lower in the alcohol blend tests.