Mutagenic compounds in chlorinated pulp bleaching waters and drinking waters.

A review is given of the isolation and identification of the extremely strong bacterial mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone, coded MX, in wood pulp chlorination waters in 1980. This compound is one of the most potent known mutagens, as determined by the Ames test. In 1986 this compound was found also in chlorinated drinking water. MX accounts for a substantial portion of the mutagenicity of chlorinated drinking waters. Several other compounds related to MX have recently been identified in chlorinated waters, such as the geometric isomer (E-MX), the oxidized and reduced forms of MX and the oxidized form of E-MX. Brominated analogues of MX may be formed by chlorination in the presence of bromide ions. Unanswered questions pertaining to the chemistry and genotoxicity of MX and related chlorinated mutagens are examined.