2.19 INHALATION OF RESUSPENDED SOIL


    The atmospheric transport pathway and the measured soil pathways involve material contained in soil. This material may be suspended and inhaled by nearby individuals resulting in inhalation exposure. The atmospheric transport component provides estimates of soil deposition from which the concentration in soil over the exposure period may be estimated. The soil concentration is used as the starting point in the resuspension model to estimate the air concentration to which individuals are exposed.
Transport Medium:
soil concentration at the location of the exposed individual, Casi, pCi/m2 or mg/m2, expressed as an annual deposition accumulation value

Special Process:
accumulation of pollutants in soil over the exposure duration for the soil ingestion pathway resuspension of pollutants in soil to air

Exposure Factors:
ingestion rate of soil, event frequency, and exposure duration.

    The soil concentration is provided from the atmospheric transport analysis as an average annual deposition amount averaged over a 70-year exposure period. The accumulation of pollutants in soil over a multiple-year exposure duration is estimated using the deposition and accumulation Equations (19) and (20). The concentration in the air above the contaminated soil is estimated by using the resuspension factor method. This method relates the air concentration to soil concentration by a single factor to represent the average ratio of air concentration to soil concentration.

    The average daily dose for chemical pollutants from inhalation of resuspended pollutants following atmospheric transport and deposition is evaluated as follows:

(101)



where
For radionuclide pollutants, the total lifetime dose is evaluated as follows:

(102)



where
    When the measured soil pathway is used, the soil concentration is expressed per unit mass of soil (rather than per unit area as for the atmospheric transport pathway). The air concentration is evaluated for the measured soil pathway using a mass loading factor that provides the amount of soil airborne. This airborne soil is assumed to have the same pollutant concentration as the measured soil.
Transport Medium:
measured soil concentration at selected locations, Cmsi, pCi/kg or mg/kg, expressed as the amount present at the start of the first 70-year period

Special Process:
loss of pollutant from the soil according to the defined soil retention half time suspension of soil containing the pollutants

Exposure Factors:
inhalation rate and exposure duration.

    The soil average concentration is evaluated using Equation (32) and is used to estimate the average daily dose for inhalation of suspended pollutants as follows:

(103)



where
For radionuclide pollutants, the total lifetime dose is evaluated as follows:

(104)



where
and other terms are as previously defined.