Chlorinated furanones

3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) (endorsed 1996)

Guideline

Data are inadequate to set a guideline value for MX in drinking water.

General description

The organic compound known as MX can be formed by the reaction between chlorine and naturally occurring organic matter in water. It has been identified in chlorinated humic acid solutions, after the chlorination of pulp mill effluent, and chlorinated drinking water. No other sources of MX are known.

The stability of MX is dependent on pH. Below pH 7 it is relatively stable but above pH 7 it rapidly breaks down.

Studies in the United States, the United Kingdom and Finland have found extremely low MX concentrations in drinking water. Concentrations range up to 0.000067 mg/L (67 ng/L).

Typical values in Australian drinking water

Preliminary investigations indicate that concentrations of MX in Australian drinking water are likely to be similar to those found overseas.

Limiting formation in drinking water

The presence of MX in drinking water can be minimised by removing naturally occurring organic matter from the source water, by reducing the amount of chlorine added, by the use of alternative disinfectants, or by ensuring that the pH is kept above 7.

Measurement

MX is extremely difficult to detect because of the very low concentrations and the masking effects of other substances. Analysis is by extraction on XAD resin, methylation of the concentrate, and detection on a gas chromatography/mass spectrometer system employing selected ion monitoring techniques. The procedure is not suitable for routine analysis.

Health considerations

There are no data on the health effects of MX in humans, nor are there any long-term or lifetime toxicity data for animals.

Studies have shown that MX is an extremely potent mutagen when applied to some strains of bacteria, and about a third of the mutagenicity of chlorinated drinking water has been attributed to this compound. Genotoxic activity has also been observed in vitro using cultured mammalian cells, although in vivo experiments showed no evidence of genotoxic activity. No carcinogenicity data are available for MX.