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Re: EPA, risk and dose
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In a message dated 03/29/2001 6:13:52 AM Pacific Standard Time,
StokesJ@ttnus.com writes:
> Over the decades, BEIR has altered the risk associated with a
> given level of dose. Therefore the risk associated with a given dose is not
> a constant. Therefore a decision made based on a given dose now, may
> change later, based on the same dose, as the risk associated with that dose
> changes. Therefore dose correlates to risk only at a given point in time,
>
I understand this to a point, and the point at which I say "huh?" is if EPA
is not assigning the "risk" from the dose, how in the world is it assigning
it? I mean the inhalation and ingestion HEAST factors are in units of risk
per pCi (of intake), so EPA's saying that they can assign a "risk" to an
intake of a pCi of a radionuclide, and while the risk from the dose the
intake delivers may change, the inherent risk from the intake will not? This
makes no sense to me.
I mean, if a BEIR committee comes out one year and says, "the risk from 25
millirem is a 5E-4 increased risk of cancer over a lifetime," then the next
year says, "the risk from 50 millirem is a 5E-4 increased risk of cancer over
a lifetime," then this affects the risk from the intake. E.g., in the first
case, the risk from an intake of 1 microcurie of Cs-137 is 5E-4, and the next
year the risk from an intake of 2 microcuries of Cs-137 is 5E-4. EPA hasn't
avoided anything from trying to cut dose out of the process because the
intake and dose are intimately related. Sure, the models will change, as our
information and knowledge-base grows, but then both the dose assignment and
risk will change. You can't avoid the fact that the risk arises from the
dose delivered to the exposed person. Am I making sense here?
Barbara L. Hamrick
BLHamrick@aol.com
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<HTML><FONT FACE=arial,helvetica><FONT SIZE=2>In a message dated 03/29/2001 6:13:52 AM Pacific Standard Time,
<BR>StokesJ@ttnus.com writes:
<BR>
<BR>
<BR>
<BR><BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Over the decades, BEIR has altered the risk associated with a
<BR>given level of dose. Therefore the risk associated with a given dose is not
<BR>a constant. Therefore a decision made based on a given dose now, may
<BR>change later, based on the same dose, as the risk associated with that dose
<BR>changes. Therefore dose correlates to risk only at a given point in time,
<BR>and therefore is not an absolute value.</BLOCKQUOTE>
<BR>
<BR>
<BR>
<BR>I understand this to a point, and the point at which I say "huh?" is if EPA
<BR>is not assigning the "risk" from the dose, how in the world is it assigning
<BR>it? I mean the inhalation and ingestion HEAST factors are in units of risk
<BR>per pCi (of intake), so EPA's saying that they can assign a "risk" to an
<BR>intake of a pCi of a radionuclide, and while the risk from the dose the
<BR>intake delivers may change, the inherent risk from the intake will not? This
<BR>makes no sense to me.
<BR>
<BR>I mean, if a BEIR committee comes out one year and says, "the risk from 25
<BR>millirem is a 5E-4 increased risk of cancer over a lifetime," then the next
<BR>year says, "the risk from 50 millirem is a 5E-4 increased risk of cancer over
<BR>a lifetime," then this affects the risk from the intake. E.g., in the first
<BR>case, the risk from an intake of 1 microcurie of Cs-137 is 5E-4, and the next
<BR>year the risk from an intake of 2 microcuries of Cs-137 is 5E-4. EPA hasn't
<BR>avoided anything from trying to cut dose out of the process because the
<BR>intake and dose are intimately related. Sure, the models will change, as our
<BR>information and knowledge-base grows, but then both the dose assignment and
<BR>risk will change. You can't avoid the fact that the risk arises from the
<BR>dose delivered to the exposed person. Am I making sense here?
<BR>
<BR>Barbara L. Hamrick
<BR>BLHamrick@aol.com</FONT></HTML>
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