here of the level of generality at which it will promulgate norms implementing a legislative mandate.” (citation omitted)). 11 . For example, with respect to cancer risks, a risk threshold might be presented as "1 x 10 A” signifying that an individual "is estimated to have up to a one in 100,000 chance of developing cancer during his/her lifetime from the exposure being evaluated.” Coalition Br. 5; see id. at 35. 12 . See National Wildlife Fed'n v. EPA, 286 F.3d 554, 566-67 (D.C.Cir.2002) (concluding that EPA reasonably interpreted Clean Water Act § 301(b)(2) as permitting it to regulate color pollutants on a case-by-case basis, because their impact "is driven by highly site-specific conditions” (citation omitted)); Chemical Waste Mgmt., Inc. v. EPA, 976 F.2d 2, 31 (D.C.Cir.1992) (<HOLDING>). 13 . See Public Citizen, Inc. v. FAA, 988
holding that the corroborative testing requirement of a rcra regulation was not impermissibly vague and that details can be resolved on a sitespecific casebycase basis holding that a state medicaid agency can review the medical necessity of treatment prescribed by a doctor on a casebycase basis holding that whether an exchange is substantially contemporaneous must be determined on a casebycase basis holding that verbal requirement of need not contained in hunting regulation was addition of substance and thus regulation under apa holding that term unreasonably loud is not impermissibly vague