MX and Other Potentially Hazardous Chlorinated By-Products

Abstract

Surface water is the main source of drinking water in many countries. Chlorination of water is, for technological and economic reasons, the commonly used disinfection method, despite the fact that some of the numerous chlorination by-products are considered potentially harmful to human health.The aim of the chapter is to present state of the art findings in the field of chlorination on a by-product found in drinking water known as MX, i.e., 3-chloro-4-(dichloromethyl)-5hydroxy-2(5H)-furanone, which is discussed in detail, due to its high potential mutagenicity and common presence in tap water.Chlorination by-products such as chloroform and other trichloromethanes have been known for over 20 years. In 1986, a strongly mutagenic compound, namely: 3-chloro-4(dichloromethyl)-5-hydroxy-2(5H) furanone (MX) was identified in chlorinated waters. Its presence in tap waters was confirmed in many countries.Commonly, at least 30% of mutagenic activity in drinking water is due to MX. The mutagenic activity of MX is comparable with the activity of aflatoxin. Due to its high activity and common presence in tap water, the World Health Organization has placed MX on the list of disinfection by-products potentially hazardous to humans. Yet, due to the lack of adequate toxicological data and rather complicated analytical procedures, no guidelines for MX in drinking water have yet been established. However, in the recent draft of the Third Edition of the WHO Guidelines for Drinking-Water Quality, the recommended value associated with a 10−5 risk is 1.8 μg 1−1, which is much above of commonly found concentrations.Extensive review of international literature on the subject as well as the authors’ own research, particularly on MX analyses, were used as the basis of this chapter.KeywordsChlorination by-productsWaterDisinfectantsMXHalogenated hydroxyfuranones