ABSTRACT
In 2012, the US Air Force (USAF) drinking water program began a long, difficult, and still ongoing journey: understanding and responding to US Environmental Protection Agency (USEPA) health advisory levels (HALs) for perfluorooctane sulfonate and perfluorooctanoic acid in drinking water. This chapter discusses the differences between maximum contaminant levels (MCLs) and HALs, potential challenges encountered by public water systems (PWSs) when responding to USEPA drinking water HALs, the Safe Drinking Water Act regulatory process, and observations about the future of drinking water HALs. An MCL is the maximum permissible level of a contaminant in water that is delivered to any user of a PWS. HALs may be developed for a number of reasons, which can include providing technical information to state agencies and other public health officials on health effects, analytical methodologies, and treatment technologies associated with drinking water contamination, or to respond quickly to a localized situation where no guidance exists.
