PM2 DNA damage induced by 3-chloro-4-(dichloromethyl)-5-hydroxy-2 (5H)-furanone (MX).

3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) is a potent direct-acting mutagen found in chlorinated drinking water. In the present study, the induction of DNA strand breaks and apurinic/apyrimidinic (AP) sites by MX in supercoiled PM2 DNA was examined using exonuclease III, which specifically cleaves the DNA at AP sites. The results showed that MX induced AP sites in great excess of direct strand breaks. In view of the known mutagenicity of AP sites, these results provide insight into the mechanism of MX-induced mutagenesis.