Carcinogens from water disinfection

Water is the basic constituent of all living beings; it is, therefore, an essential dietaryelement and a primary resource. The International standard references concerningdrinking-water are various and, based on WHO guidelines (WHO 2004), are diversifiedin relation to local problems. Disinfection of water for human consumption could beconsidered the most significant public health measure taken during the last century;destroying pathogens in drinking water has drastically reduced the incidence ofwaterborne diseases in all industrialized countries. Chlorination is currently used as watertreatment due to its action; it is preferred to ozonization because is less expensive andleads to residual action. The use of hypochlorite ion (ClO–) is preferred to chlorination bychlorine dioxide (ClO2) and chlorine gas (Cl2); however, it does not guarantee theabsolute absence of risks. The addition of those chemicals to water leads to the formationof other compounds, many of which are toxic, as they can cause, among other things,chronic diseases and cancer. This review will primarily highlight the risks thatchlorination, as a water purifying treatment, may pose to the population health, as itcauses the formation of various by-products, many of which are known to becarcinogenic.Epidemiological studies have been carried out in order to highlight the possibleexcess of cancer in populations drinking water treated with chlorine or ozone.Trihalomethanes, Haloacetic acid, Haloacetonitriles, 3-chloro-4-dichloromethyl-5-hydroxy-2(5H)-furanone or MX and bromate are all identified as Disinfection/Disinfection By-Products.