The EPA has decided against regulating 11 of the 51 contaminants on its second drinking water contaminant candidate list (CCL 2), but is updating health advisories for seven of them: boron; the dacthal mono- and di-acid degradates; 1,3-dichloropropene (Telone); 2,4-dinitrotoluene and 2,6-dinitrotoluene; and 1,1,2,2-tetrachloroethane.

Updated or new health advisories aren't necessary for 1-dichloro-2,2-bis (p-chlorophenyl) ethylene (DDE); s-ethyl propyl thiocarbamate (EPTC); Fonofos; and Terbacil because national monitoring data showed almost no occurrence at levels of public health concern.

A regulatory determination is a formal decision on whether the agency should initiate a rulemaking process to develop a regulation for a specific contaminant. Under the Safe Drinking Water Act, every five years the EPA develops a CCL and makes a regulatory determination for at least five contaminants on the list.