; and (II) perfluorooctane sulfonic acid (commonly referred to as PFOS ); and (ii) standards for, as individual contaminants or as a mixture, perfluorononanoic acid (commonly referred to as PFNA ), hexafluoropropylene oxide dimer acid (commonly known as GenX Chemicals ), perfluorohexane sulfonic acid (commonly referred to as PFHxS ), and perfluorobutane sulfonic acid (commonly referred to as PFBS ). (B) Alternative procedures (i) In general Not later than 1 year after the validation by the Administrator of an equally effective quality control and testing procedure to ensure compliance with the national primary drinking water regulation promulgated under subparagraph (A) to measure the levels described in clause (ii) or other methods to detect and monitor perfluoroalkyl and polyfluoroalkyl substances in drinking water, the Administrator shall add the procedure or method as an alternative to the quality control and testing procedure described in such national primary drinking water regulation by publishing the procedure or method in the Federal Register in accordance with section 1401(1)(D). (ii) Levels described The levels referred to in clause (i) are— (I) the level of a perfluoroalkyl or polyfluoroalkyl substance; (II) the total levels of perfluoroalkyl and polyfluoroalkyl substances; and (III) the total levels of organic fluorine. (C) Inclusions The Administrator may include a perfluoroalkyl or polyfluoroalkyl substance or class of perfluoroalkyl or polyfluoroalkyl substances on— (i) the list of contaminants for consideration of regulation under paragraph (1)(B)(i), in accordance with such paragraph