Multitechnique Screening of Chicago Municipal Sewage Sludge for Mutagenic Activity

A sample of anaerobically digested Chicago municipal sewage sludge has been examined for mutagenicity by using a variety of biological assays with different genetic end points. The sludge clearly contains components that induce mutagenic responses in all of the species employed. Acetone extracts from the equivalent of 155 µL of neat sludge induced a doubling in the number of revertant colonies of the Ames Salmonella typhimurium strain TA98 after activation with mammalian microsomes. In situ and laboratory studies indicate the induction of point mutations in the germ cells of Zea mays. Cytogenetic damage was demonstrated by the increased frequency of micronuclei observed in meiotic cells of Tradescantia paludosa.