Oxyhalide Disinfection By-Products in Packaged Drinking Water and their Associated Risk

Disinfection by-products (DBPs) are formed during treatment of water for drinking purposes. Among these oxyhalide DBPs, viz. bromate, chlorate and chlorite are potentially harmful to humans. In the present study packaged drinking water samples of various commercial brands, available in Mumbai, were analysed for bromide, bromate, chlorite and chlorate ions using ion chromatography. The average concentration levels of bromide, bromate, chlorite and chlorate in packaged drinking water were 28.4, 10.7, 7.1 and 20.8 μg/l respectively. Bromate in 27% samples was found to be higher than the World Health Organization (WHO) guideline value of 10 μg/l, whereas chlorite and chlorate levels were well within the guideline value recommended by WHO. A good correlation between bromide and bromate (r=0.85) indicated formation of bromate from bromide present in drinking water. Health risks (carcinogenic risk and hazard quotient) associated with ingestion of bromate, chlorite and chlorate present in packaged drinking water are presented and discussed.