Minimizing Halogenated Mutagens In Water

Halogenated furanones can be produced in drinking water by the reaction of naturally occurring organic matter and bromide with the disinfectant chlorine. Although halogenated furanone compounds are mutagenic, research on their concentrations in drinking water is at an early stage and they are not regulated by EPA. Gretchen D. Onstad of the University of Washington, Seattle; Howard S. Weinberg of the University of North Carolina, Chapel Hill; and Stuart W. Krasner of the Metropolitan Water District of Southern California now report how the formation of halogenated furanones can be affected by different water-treatment methods (Environ. Sci. Technol., DOI: 10.1021/es071374w). The group studied water from six pairs of treatment plants in which each member of a pair used a different scheme to treat water. The researchers used gas chromatography with microelectron capture detection to analyze the samples for 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (shown), known as MX, as well as a dozen MX analogs. The highest levels of halogenated furanones, as much as 1 μg/L of one of the analogs, were produced when disinfection began with chlorine or chloramine. Treatment plants produced much less of the targeted compounds when they used ozonation, which is thought to degrade furanone precursors, followed by filtration and then chlorination or chloramination.