EQUATION FOR CALCULATION OF MHRV FOR NONCARCINOGENIC EFFECTS OF TOXICANTS

Subpart 1. Scope. This part establishes the method for determining the multimedia health risk value (MHRV) for a noncarcinogenic effect of a toxicant emitted to the air. Subp. 2. Equation for MHRV for noncarcinogenic effect of toxicant. The equation for calculating a MHRV for a noncarcinogenic effect of a toxicant is: NOAEL or LOAEL or BMD MHRV = -------------------------------------------------- × 1,000 (Uncertainty factor) (Modifying factor) Where: A. MHRV is expressed in units of micrograms of chemical or defined mixture of chemicals per kilogram of body weight per day (µg/kg-day); B. NOAEL, LOAEL, or BMD is expressed in units of milligrams of chemical or defined mixture of chemicals per kilogram body weight per day (mg/kg-day); C. uncertainty factor and modifying factor are unitless; D. the default value for modifying factor is one unless otherwise specified in part 4717.8250 ; and E. 1,000 is a factor to convert milligrams to micrograms.