Study of the behaviour of mutagens in wastewater and emission gas from a municipal incinerator evaluated by means of the Ames assay.

We have investigated the mutagenic activity of extracts from the wastewater of sewage treatment plants in municipal waste incinerators and evaluated the relative contribution of various routes of emission from the incinerator to the total output of mutagens. The mutagenicity of wastewater extracts from a complete combustion incinerator was 10% of that from an incomplete combustion unit. About 90% of all the mutagens produced in a municipal incinerator are discharged into the atmosphere as emission gases, and 10% are disposed of in the wastewater treatment plants. Most of the mutagens in wastewater treatment plants are not decomposed by normal aeration times, but are removed by adsorption onto suspended solids.