Mutagenicity of exhaust gas from incineration plants of municipal waste

The Ames mutagenicity test of exhaust gas and fly ash from 16 incineration plants of municipal waste were investigated using TA98 and TA100 bacteria strains, with or without the S9 mixture. Exhaust gas showed high mutagenicity levels, especially the the flame shift type with mebabolic action (TA98 + S9). Exhaust gas samples from fluidized bed type incinerators showed a higher mutagenicity than those from stoker type incinerators, and exhaust gas samples from old plants also showed a higher mutagenicity. Since many mutagens were produced under the conditions of incomplete combustion, levels could be decreased by secondary combustion and a sufficient supply of air. The mutagenicity of fly ash was much lower than that of exhaust gas, and the mutagens were condensed slightly from the gas to fly ash at the temperature of the electroprecipitator.