Determining the Human Nonthreshold Criterion

Section 302 Section 302.657  Determining the Human Nonthreshold Criterion The HNC is calculated according to the equation: HNC = RAI/[W + (F x BCF)] where: HNC = Human Nonthreshold Protection Criterion in milligrams per liter (mg/L); RAI = Risk Associated Intake of a substance in milligrams per day (mg/d) that is associated with a lifetime cancer risk level equal to a ratio of one to 1,000,000 as derived in Section 302.654; W = Per capita daily water consumption equal to 2 liters per day (L/d) for surface waters at the point of intake of a public or food processing water supply, or equal to 0.01 liters per day (L/d) which represents incidental exposure through contact or ingestion of small volumes of water while swimming or during other recreational activities for areas which are determined to be public access areas under Section 302.102(b)(3), or 0.001 liters per day (L/d) for other waters; F = Assumed daily fish consumption in the United States equal to 0.020 kilograms per day (kg/d); and BCF = Aquatic Life Bioconcentration Factor with units of liter per kilogram (L/kg) as derived in Section 302.663.