Perchlorate, bromate, and chlorate in hypochlorite solutions: Guidelines for utilities

V arious forms of chlorine are commonly used in drinking water and water reuse applications for their ability to disinfect and maintain a residual level of disinfectant throughout the distribution system. The majority of utilities in the United States use chlorine gas during treatment, but approximately one third of all US drinking water treatment plants use bulk hypochlorite for disinfection, and around 8% use onsite hypochlorite generators or onsite generators (OSGs) during treatment (Routt et al, 2008a, 2008b). Hypochlorite solutions contain many regulated and unregulated contaminants, including bromate, chlorite, chlorate, and perchlorate (Asami et al, 2009; Greiner et al, 2008; Weinberg et al, 2003; Gordon et al, 1993). The perchlorate ion (referred to here as perchlorate) has been identified as a contaminant of concern in hypochlorite solutions and drinking water and has drawn much attention because it is an endocrine-disrupting chemical that can affect the human thyroid system (Greer et al, 2002; York et al, 2001; Urbansky, 2000; Lamm et al, 1999). Furthermore, on the basis of both data BENJAMIN D. STANFORD,