(6)Equation 6 (radionuclides) and Table 5 present the exposure variables for the external exposure pathway for the residential, industrial, recreational, excavation, and recreational scenarios.
(6)
Table 5. Soil/Sediment External Exposure Parameters
|
Parameter |
Units |
Residential |
Industrial |
Recreational |
Excavation |
Agricultural |
|
Radionuclide chemical concentration in soil = Csr |
pCi/g |
Chemical-specific |
Chemical-specific |
Chemical-specific |
Chemical-specific |
Chemical-specific |
|
Gamma Shielding Factor = Se |
unitless |
0.2 (EPA 1991a) |
0.2 (EPA 1991a) |
0.2 (EPA 1991a) |
0.2 (EPA 1991a) |
0.2 (EPA 1991a) |
|
Gamma exposure time factor = Te |
unitless |
1 (EPA 1991a) |
8/24 (EPA 1991a) |
1/24 (EPA 1991a) |
8/24 (EPA 1991a) |
1 (EPA 1991a) |
|
Exposure frequency = EF |
days/yr |
350 (EPA 1989a) |
250 (EPA 1991a) |
40 (EPA 1992) |
20 |
350 (EPA 1989a) |
|
Exposure duration = ED |
years |
24 (adult) 6 (child) (EPA 1989a) |
25 (adult) (EPA 1991a) |
24 (adult) 6 (child) (EPA 1989a) |
1 |
24 (adult) 6 (child) (EPA 1989a) |
|
Conversion factor = CF9 |
yr/days |
1/365 |
1/365 |
1/365 |
1/365 |
1/365 |