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ADDITIONAL INFORMATION REGARDING SCREENING LEVEL • <br />ASSESSMENT <br />Calculation of BLM Risk Management Criteria (RMC) <br />The following equations and supporting information are from the Risk Based Criteria for Metals at <br />BLM Mining Sites (BLM 2004, Appendix A). Arsenic, when ingested by humans in soil, is <br />carcinogenic as well as toxic (e.g., non-carcinogenic). Non-carcinogenic and carcinogenic risk <br />evaluations are presented below. <br />Non-Carcinogenic Risk Evaluation: The RMC calculation for non-carcinogenic hazards from <br />exposure to soil (residential, campground host, camper, ATV driver, recreational maintenance <br />worker, and surveyor receptors) is as follows: <br />Where, <br />RMC or CS = Chemical Risk Management Criteria in Soil (mg/kg) <br />THI = Target Hazard Index (unitless) <br />NCAT = Noncarcinogenic Averaging Time (period over which exposure resulting <br />in noncarcinogenic effects is averaged - years) • <br />EF = Exposure Frequency (days/year) <br />RfDo = Oral Chronic Reference Dose (mg/kg-day) <br />IRS = Age Adjusted Soil Ingestion Rate (mg-yr/kg-day) <br />CF = Conversion Factor (kg/mg) <br />NNCO = Number of COCs with an Oral Chronic Reference Dose (unitless) <br />RfDi = Inhalation Chronic Reference Dose (mg/kg-day) <br />IHR = Inhalation Rate (m3/hr) <br />PEF = Particulate Emission Factor (m3/kg) <br />NNCI = Number of COCs with an Inhalation Chronic Reference Dose (unitless) <br />MN = Number of Media <br />Carcinogenic Risk Evaluation: The RMC calculation for carcinogenic hazards from exposure to <br />soil (residential, campground host, camper, ATV driver, recreational maintenance worker, and <br />surveyor receptors) is as follows: <br />dl ? TRxAT k,565 <br />SP, <br />Where, <br />RMC or CS = Chemical Risk Management Criteria in Soil (mg/kg) • <br />TR = Target Excess Individual Lifetime Cancer Risk (unitless)