Re: Benchmark for CERCLA comparison

[GACarlson@aol.com]

I direct your attention to the following EPA web pages as a start for federal 
guidance on radiation risk assessments for CERCLA sites:
 
http://www.epa.gov/radiation/federal/index.html
http://www.epa.gov/radiation/cleanup/

In CERCLA the issue is not so much dose as much as risk.  In general, for 
ingestion or inhalation of radionuclides, the standard risk assessment 
methods (EPA Risk Assessment Guidance for Superfund (RAGS), see 
http://www.epa.gov/superfund/programs/risk/ragsd/index.htm) are used to 
determine the amount of the medium (soil, water, air, etc.) ingested or 
inhaled.  Total activity ingested or inhaled is then calculated from the 
specific activity of the medium, and dose conversion factors then give the 
corresponding internal dose.  I don't have the reference right in front of 
me, but in 1991 the NRC published in the Federal Register a factor for 
converting dose in rem to cancer risk.  The cancer risk is then calculated 
from this or some other defensible number and is then compared to the the EPA 
CERCLA cancer risk range of 10-4 to 10-6.  Assessment of external exposures 
simply :) involves calculating the dose and converting to cancer risk.

With regard to the applicability of NRC decommissioning rule dose limits for 
CERCLA sites, the following excerpt from OSWER 9200.4-18, August 22, 1997, is 
particularly noteworthy:

"However, EPA has determined that the dose limits established in this rule 
[the NRC's Radiological Criteria for License Termination rule (62 Federal 
Register 39058, July 21, 1997)] as promulgated generally will not provide a 
protective basis for establishing preliminary remediation goals (PRGs) under 
CERCLA. . . . Accordingly, while the NRC rule standard must be met (or 
waived) at sites where it is applicable or relevant and appropriate, cleanups 
at these sites will typically have to be more stringent than required by the 
NRC dose limits in order to meet the CERCLA and NCP requirement to be 
protective."  

Good luck.

Glenn 
GACarlson@aol.com

>  In a message dated 04/07/99 10:26:37 AM Central Daylight Time, 
BLHamrick@aol.
> com writes:
>  
>  > Subj:	 Re: Benchmark for CERCLA comparison
>  >  
>  >  In a message dated 4/7/99 7:51:12 AM Pacific Daylight Time, 
>  >  thenry@viperlink.net writes:
>  >  
>  >  << Am I correct in my understanding that dose criteria / limits are only
>  >   defined for workplace exposures?  Are there any dose criteria for
>  >   "residential" scenarios?
>  >   
>  >   Any suggestions or references to EPA, NRC or other entity guidance or
>  >   regulation is greatly appreciated. >>
>  >  
>  >  The NRC's decommissioning rule does not distinguish between residential 
> and 
>  >  industrial per se.  The limit is 25 millirem per year TEDE to the "
> average 
>  >  member of the critical group."
>  >
>  >  Barbara L. Hamrick
>  >  BLHamrick@aol.com
>  >  
>  

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