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EPA, risk and dose
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I have a question - possibly a few. Please don't laugh. I have been reading
EPA's guidance on CERCLA evaluations at NRC licensed or decommissioned sites.
I repeatedly run into statements by the EPA that they should not be
evaluating potential dose, but rather potential risk, using their HEAST
factors. Here comes my question(s):
If there is no dose, there is no risk, right?....So, how does one estimate
risk, with blinders on to dose? I mean, an agency can ask to express a limit
in certain units, and if EPA likes risk over dose, then fine, but they seem
to imply you can't easily relate the two, and that where I have a problem,
because if you're not imparting energy to human tissue (delivering dose),
then there is no risk, so either there is a definable relationship between
the two, so that you can convert between dose and risk, or there is not, in
which case you can only speak about dose (which is measurable). Otherwise
where in the heck are the risk numbers coming from?
Also, in a back of the envelop (literally) calculation comparing EPA's "risk"
factors to dose (heaven forbid), I find that their factor for inhalation of
C-14 would put their upper-bound of acceptability (i.e., an increased
lifetime risk of cancer at 10E-4) at about 35 rem over an average occupancy
of 30 years (if you use the ALIs in 10 CFR 20 to convert intake to dose), or
about 1.2 rem per year...Is this, possibly, why they don't want to talk dose?
Just respectfully wondering.
Barbara L. Hamrick
BLHamrick@aol.com
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<HTML><FONT FACE=arial,helvetica><FONT SIZE=2>I have a question - possibly a few. Please don't laugh. I have been reading
<BR>EPA's guidance on CERCLA evaluations at NRC licensed or decommissioned sites.
<BR> I repeatedly run into statements by the EPA that they should not be
<BR>evaluating potential dose, but rather potential risk, using their HEAST
<BR>factors. Here comes my question(s):
<BR>
<BR>If there is no dose, there is no risk, right?....So, how does one estimate
<BR>risk, with blinders on to dose? I mean, an agency can ask to express a limit
<BR>in certain units, and if EPA likes risk over dose, then fine, but they seem
<BR>to imply you can't easily relate the two, and that where I have a problem,
<BR>because if you're not imparting energy to human tissue (delivering dose),
<BR>then there is no risk, so either there is a definable relationship between
<BR>the two, so that you can convert between dose and risk, or there is not, in
<BR>which case you can only speak about dose (which is measurable). Otherwise
<BR>where in the heck are the risk numbers coming from?
<BR>
<BR>Also, in a back of the envelop (literally) calculation comparing EPA's "risk"
<BR>factors to dose (heaven forbid), I find that their factor for inhalation of
<BR>C-14 would put their upper-bound of acceptability (i.e., an increased
<BR>lifetime risk of cancer at 10E-4) at about 35 rem over an average occupancy
<BR>of 30 years (if you use the ALIs in 10 CFR 20 to convert intake to dose), or
<BR>about 1.2 rem per year...Is this, possibly, why they don't want to talk dose?
<BR>
<BR>Just respectfully wondering.
<BR>
<BR>Barbara L. Hamrick
<BR>BLHamrick@aol.com</FONT></HTML>
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