The genotoxity of by-products by chlorination and ozonation of the river water in the presence of bromide ions

Abstract

This study focused on the evaluation of the genotoxic characteristics of chlorinated and brominated substances produced by ozonation and chlorination of the river waters containing bromide ions. The mutagenic activities of drinking waters and disinfected river waters were measured by Ames tests using S. typhimurium strains TA100 and TA98, and by chromosomal aberration test using cultured Chinese hamster lung cells (CHL/IU) in vitro. After flowing samples through CSP800 or XAD-2 resin column, absorbed substances dissolved in dimethyl sulfoxide, and submitted to the mutagenicity assays. Correlation was high between water qualities revealed by chemical analysis and mutagenic potentials. Mutagenic activities of the drinking waters produced by chlorination were observed to be higher than those by ozonation. Chlorinated waters highly increased in cells with the exchange- and chromatid-type of chromosomal aberrations compared with unchlorinated waters. The increase of mutagenic potentials was caused by by-products when bromide ions were substituted for chloride ions with various ratios.