Re: LNT, Collective Dose

[BLHamrick@aol.com]

And, I think, in general, the LNT is the fallback position, at least for the EPA.  From the D.C. Circuit Court: Argued February 11, 2000 Decided March 31, 2000,  No. 98-1627, Chlorine Chemistry Council and Chemical Manufacturers Association, Petitioners v. Environmental Protection Agency, Respondent:

"On July 29, 1994 EPA issued a proposed rule on disinfectants and disinfection byproducts in water. This included a zero MCLG for chloroform, based on EPA's finding of an absence of data to suggest a threshold level below which there would be no potential carcinogenic effects. Id . The Agency's default method of inferring risk at exposure levels for which it has no adequate data is linear extrapolation from cancer incidence inferred at exposures for which it does have data. See EPA's Proposed Guidelines for Carcinogen Risk Assessment, 61 Fed. Reg. 17,960, 17,968/3 (1996). Thus, either if the evidence supports linearity, or if there is "insufficient" evidence of nonlinearity,
EPA assumes that if a substance causes cancer at any exposure it will do so at every non-zero exposure (though with cancer incidence declining with expo- sure). But EPA acknowledges its authority "to establish nonzero MCLGs for carcinogens if the scientific evidence" indicates that a "safe threshold" exists. See Final Rule, 63 Fed. Reg. at 69,401/2. And petitioners here assume the validity of the linear default assumption. "

Barbara L. Hamrick
BLHamrick@aol.com

In a message dated Fri, 23 Feb 2001  3:03:22 PM Eastern Standard Time, "Tony Harrison" <laharris@smtpgate.dphe.state.co.us> writes:

<< 
Not entirely true.  The OSHA standard for asbestos was reduced about
five years ago from 0.2 to 0.1 fibers per cc (if memory serves) even
though the epi studies showed no risk at such low exposures.  OSHA may
not have cited the LNT as a model, but it's implied in setting such low
limits.  Risk assessments for second hand smoke were also conducted the
same way, but again, no one spelled out LNT.  The assumption is that
"everyone knows" and the model never gets tested.

Tony Harrison, RSO, MSPH
Laboratory and Radiation Services Division
Colorado Dept. of Public Health & Environment
tony.harrison@state.co.us 


>>> tom.mohaupt@wright.edu 02/23/01 11:17AM >>>
A good example of LNT is the number of cancer deaths purported by the
EPA.
They say that 7,000 to 30,000 people in the US die from radon each
year...

 What strikes me as bizarre is that of all the "known" carcinogens for
lung cancer, the LNT is essentially the only one applied to radon. From
the studies I've read while trying to make sense of the radon issue, the
LNT is not applied to second hand smoke, pulmonary fibrosis, diet, or
even smoking.

Tom


************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
 >>


************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html