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External Exposure

 

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