Human and Ecological Risk Assessment - Earthjustice

Appendix GHuman Health BenchmarksAppendix G. Human Health BenchmarksThe CCW screening analysis and risk assessment require human health benchmarks toassess potential risks from chronic oral exposures. EPA uses reference doses (RfDs) to evaluatenoncancer risk from oral exposures. Oral cancer slope factors (CSFs) are used to evaluate risk forcarcinogens. This appendix provides the human health benchmarks used in the CCW screeningand risk assessment. Section G.1 describes the data sources and general hierarchy used to collectthese benchmarks. Section G.2 provides the benchmarks along with discussions of individualhuman health benchmarks extracted from a variety of sources.G.1 Methodology and Data SourcesSeveral sources of health benchmarks are available. The hierarchy used healthbenchmarks developed by EPA to the extent that they were available. The analysis usedavailable benchmarks from non-EPA sources for chemicals for which EPA benchmarks were notavailable, and ranked human health benchmark sources in the following order of preference:G.1.1• Integrated Risk Information System (IRIS)• Superfund Technical Support Center Provisional Benchmarks• Health Effects Assessment Summary Tables (HEAST)• EPA health assessment documents• Various other EPA health benchmark sources• Agency for Toxic Substances and Disease Registry (ATSDR) minimal risk levels(MRLs)• California Environmental Protection Agency (CalEPA) chronic inhalation referenceexposure levels (RELs) and cancer potency factors.Integrated Risk Information System (IRIS)Benchmarks in IRIS are prepared and maintained by EPA, and RTI used values fromIRIS whenever available. IRIS is EPA’s electronic database containing information on humanhealth effects (U.S. EPA, 2009). Each chemical file contains descriptive and quantitativeinformation on potential health effects. Health benchmarks for chronic noncarcinogenic healtheffects include RfDs and inhalation reference concentrations (RfCs). Cancer classification, oralCSFs, and inhalation unit risk factors (URFs) are included for carcinogenic effects. IRIS is theofficial repository of Agency-wide consensus of human health risk information.April 2010–Draft EPA document. G-1