Re: Re[2]: Cs137 in soil and cancer risk

[Jean-Michel Mure <Jean-Michel.Mure@andra.fr>]

Alex,

These figures are for external exposure from a contaminated soil only.
Pathways such as ingestion or inhalation are out of the scope of the initial
question raised by Mike Baker who is only concerned with external exposure.
Anyway these Exposure to Dose coefficients are meant to be used to give an
idea of the dose (pathway=external exposure) that is related to a given
level of contamination of the soil assuming exposure occurs all time of year.

The figures are for a semi-infinite slab geometry and for exposure at 1 m.
Soil density is 1600 kg/m3. Exposure is continuous over a year.

The mistake I made is that I forgot to take into account the thickness of
contaminated soil that Mike assumed to be equal to1 cm.
The dose conversion factor hence becomes 1.9E-7 Sv/y per Bq/kg. (Ref :
External Exposure to Radionuclides in air, water and soil, exposure to Dose
Coefficients for General Application, Based on the 1987 Federal Radiation
Protection Guidance, ORNL 1993)
Csoil(Cs137)=0.629 Bq/kg
--->  EDE=1.19e-7 Sv/y assuming exposure 24h/24h and 365days/365days
--->letal cancer risk = 6e-9 cancer/y

Sorry for the initial lack of detail.

Best regards
JM



 

At 16:05 07/01/1997 -0600, you wrote:
>
>_
>>Dose conversion factor for a contaminated soil assuming Ba137m and Cs137 are
>in secular equilibirum (which is reasonably acceptable regarding Ba137m
>half-life (T=4.86E-6 y))
>= 1.09 E-6 Sv/y per Bq/kg (AECL, 1989) *
>or = 1.14E-6 Sv/y per Bq/kg (ORNL, 1993) 
>
>*********
>How have these dose conversion factors been calculated? Do they take into
>account ground shine, resuspension, transfer to food and/or water, kids eating
>dirt etc etc etc... I'm curious as to the applicability of a single "number" to
>all possible critical groups when the pathways of exposure vary with land use.
>
>Regards
>
>
>Alex Zapantis                                  
>Environmental Radiation Officer     
>Office of the Supervising Scientist		
>40 Blackall Street 														
>Barton ACT 2600 AUSTRALIA 
>            
>Email: azapantis@mgdestmx01.erin.gov.au
>Fax : (int+) 61 6 274 1519
>Phone: (int+) 61 6 274 1642
>
>The Office of the Supervising Scientist is a Branch of the 
>         Federal Environment Protection Group 
>
>
>
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