Human and Ecological Risk Assessment - Earthjustice

Appendix GHuman Health Benchmarksto EPA’s RfC, for 120 substances (CalEPA, 1999b, 2000, 2008). CalEPA used EPA’s inhalationdosimetry methodology (U.S. EPA, 1994) in the derivation of inhalation RELs. The cancerpotency factors and inhalation RELs have undergone internal peer review by various Californiaagencies and have been the subject of public comment.G.1.7Surrogate Health BenchmarksIf no human health benchmarks were available from EPA or alternative sources, wesought benchmarks for similar chemicals to use as surrogate data. For example, the healthbenchmark of a mixture could serve as the surrogate benchmark for its components or abenchmark of a metal salt could serve as the surrogate for an elemental metal.G.2 Human Health BenchmarksThe chronic human health benchmarks used to calculate the health-based numbers(HBNs) in the CCW screening analysis and risk assessment are summarized in Table G-1,which provides the Chemical Abstract Service Registry Number (CASRN), constituent name,RfD (mg/kg-d), oral CSF (mg/kg-d -1 ), and reference for each benchmark. A key to the referencescited and abbreviations used is provided at the end of the table.For a majority of constituents, human health benchmarks were available from IRIS (U.S.EPA, 2009), Superfund Provisional Benchmarks, or HEAST (U.S. EPA, 1997). Benchmarks alsowere obtained from ATSDR (2009) or CalEPA (1999a, 1999b, 2000, 2008). This sectiondescribes benchmarks obtained from other sources, along with the Superfund ProvisionalBenchmarks values and special uses of IRIS benchmarks.Constituent NameTable G-1. Human Health Benchmarks Used in CCW Risk AssessmentCASRNRfD(mg/kg-d)Aluminum 7429-90-5 1.0E+00 PAntimony 7440-36-0 4.0E-04 IRefCSFo(permg/kg-d)Arsenic, inorganic 7440-38-2 3.0E-04 I 1.5E+0 IBarium 7440-39-3 2.0E-01 IBeryllium 7440-41-7 2.0E-03 IBoron 7440-42-8 2.0E-01 IRefMCL(mg/L)NotesCadmium 7440-43-9 5.0E-04 I RfD for H 2 O (food = 1E-3)Chloride 16887-00-6 250Chromium (III),insoluble salts16065-83-1 1.5E+00 IChromium (VI) 18540-29-9 3.0E-03 ICobalt (andcompounds)7440-48-4 3.0E-04 PCopper 7440-50-8 1.0E-02 A 1.3 RfD is the intermediate oral MRLCyanide (amenable) 57-12-5 2.0E-02 I(continued)April 2010–Draft EPA document. G-3