Mutagenicity of Nagara river sediment.

The sediments of Nagara river and its bystreams were extracted with ether. The mutagenicities of the extracts were determined by the Ames test with Salmonella typhimurium TA100 with S9 mix. The extracts were fractionated on an activated silica-gel column with four kinds of organic solvent, namely iso-octane, iso-octane:benzene (1:1), benzene:ethyl acetate (1:1) and benzene:methanol (1:1). The highest mutagenicity was observed in the iso-octane-benzene fraction of Arata river by using TA100 with S9 mix. Chemical substances in this fraction were identified by GC-MS and GC, and several kinds of polycyclic aromatic hydrocarbons (PAH) were found. Several peaks were unidentified, but these PAH, especially benzo [b] fluoranthene and benzo [a] pyrene, may contribute substantially to the mutagenicity of this fraction.