Laserfiche WebLink
V.,x <br />‘-k-- <br />92-47.08 <br />Inhalation - Roadvay materials are subjected to degrading <br />forces such as vehicular traffic and water, which nay <br />generate airborne concr.ntrations of contaminants in the form <br />of particles eroded from the surface. Direct inhalation of <br />these contaminants containing particulates by human <br />receptors is considered. Airborne concentrations are <br />calculated by U.S. EPA air estimation models utilizing local <br />Minnesota meceorological data. <br />Ingestion - Human receptors are potentially exposed through <br />oral ingestion of roadway material constituents; <br />Leached into local groundwater from the pavement. <br />These groundwater concentrations were cetermined <br />utilizing conservative U.S. EPA modeling techniques and <br />data regarding local geology and soil?. In addition, <br />the leaching solution was assumed to be much more <br />aggressive than rain water. <br />Contained in surface water runoff due to precipitation. <br />Conservative assumptions regarding road constituent <br />removal by rainfall were employed in the calculation of <br />surface water runoff constituent concentrations. <br />By direct ingestion of native soils affected by <br />deposition (settling) of the road airborne <br />particulates. Humans come into oral contact with <br />soiled hands, and soil itself in the case of small <br />children. <br />Dermal Contact - Skin contact with contaminated materials <br />(surface water runoff, roadway materials) permits the <br />absorption of some contaminants. This pathway can be <br />especially important in the case of children playing <br />outdoors. <br />Food Chain — Roadway material contaminants in the air and <br />deposited on soils may accumulate in plant and animal <br />tissues through the food chain, and present an ingestion <br />exposure pathway to human receptor through food consumption. <br />Therefore, a food chain model was chosen to evaluate this <br />potential exposure pathway. The model was developed for the <br />U.S. EPA by the Oak Ridge National Laboratory to evaluate <br />human exposure through the terrestrial food chain <br />specifically to municipal waste combustor emission^. The <br />model utilizes ambient air contaminant concentrations <br />(Mg/cu.m) and deposition rates (g/sq.m/yr.) to calculate the <br />amount of a contaminant that has accumulated in plants,