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Fwd: Benchmark for CERCLA comparison (update)
[The following is a slightly re-edited/updated version of previously sent
material, which though submitted yesterday has not appeared on RADSAFE as of
this afternoon. I apologize for any duplication.]
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. See radionuclide carcinogencity slope factors
(HEAST table) info at http://www.epa.gov/radiation/heast/. Also, in 1991 the
NRC published (56 Fed Register 23360, May 21, 1991) factors for converting
dose in rem to cancer risk (4e-4/rem for workers; 5e-4/rem for general
population). The calculated cancer risk 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
> >
>
>>
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
> >
>