effect below about 50 WLM. However, most studies, including those cited, find
this effect at higher cumulative levels. Since preliminary estimates suggest that
some Fernald workers, and possibly workers at other facilities, may be exposed
to cumulative totals considerably above 50 WLM, the decision to ignore the
inverse dose-rate effect may be premature.

If you have questions concerning any of my comments, please contact me
at 558-2767.

Sincerely,

Richard W. Hornung, DrPH


Hornung

Hornung, Richard (HORNUNRW) [HORNUNRW@UCMAIL.UC.EDU]
Sent: Friday, December 07, 2001 11:10 AM

To: Jim Neton (E-mail); 'ije1@cdc.gov'

Subject: Review of IREP document

Review of NIOSH
doc.(1).doc .
Larry/Jim
am attaching my review of the IREP document. In general, | found it to be a very good
description of IREP software. | had a few concerns that you will see in the review, some of which
may not be on target since | wasn’t sure if you wanted only comments on the documentation of
IREP or also the assumptions that went into putting it together. The main thing that | think could
improve it is a detailed example of how a typical claim’s data would be handled—including which
sources of unceriainty can be considered.

Please call me if you have any questions.

Thanks, Rick <<Review of NIOSH doc.(1).doc>>


Review of NIOSH IREP (ver. 4.0b)
Technical Documentation

Thank you for the opportunity to review this document. It is not entirely
clear to me whether you only require comments on the documentation itself or
the methodology used therein. Accordingly | will provide several comments on
both issues.

My primary comment concerns the purpose and potential audience for this
document. One of the primary improvements in the use of the IREP software
over the 1985 radio-epidemiological tables is the ability to account for uncertainty
in information used to calculate probability of causation. However, very little is
mentioned in the document about which sources of uncertainty are considered
by IREP and how they are implemented by the software. It would be very
beneficial to the reader to provide a more comprehensive description of how
IREP addresses uncertainty. If possible, the inclusion of a typical scenario (
similar to that shown in Appendix | but with more detail) for a claimant could be
included as an example. This would include going through the steps in arriving at
PC for a specific cancer type using the actual data values for that person. This
description should also mention which sources of uncertainty are not addressed.
The descriptions of the process should be tailored to the potential audience for
which it is intended.

My next comment concerns the definition of GSD as found on pages 9
and 15. The GSD is estimated by calculating the half-width of the 95%
confidence interval for the ERR and dividing by 1.96. Since the confidence
interval was originally computed using the standard error (not the standard
deviation) of the ERR, which is a function of the sample size, this estimate of the
GSD depends almost entirely on one study (Pierce, et al 1996). This may be
acceptable if this study is considered the definitive estimate for bone cancer risk.
The same argument holds for skin cancer on page 15. This point should be
made in the text. Also, it is not clear from the text how the GSD will be used. Is
this part of the uncertainty calculation?

Table 5 is similar to Table 2, but includes the risk model to be used for
each primary neoplasm. This is very important information, but requires the
reader to search elsewhere for a description of each cancer risk model. It might
be valuable to include an appendix that described each of the risk models and
their source. At the very least, Table 5 should be footnoted to direct the reader to
the appropriate reference(s) for this information.

On page 3, the document states that the revised version of IREP includes
a lung cancer model developed in 1996 by the RECA Committee from uranium
miner data. This is a much better approach than using atomic bomb survivor risk
estimates for low LET radiation and then applying RBE factors. However, Table
7 lists an RBE factor for alpha particles. Is this RBE for alpha to be used only for
exposures to such radionuclides as plutonium or uranium? If so, you may want to
footnote this at the bottom of Table 7.


On pages 6 - 9, an extensive discussion of bone cancer is given with
numerous citations from the literature. However, | saw no references to the
radium dial painters. ts this because radium exposures are not considered by the
legislation? There were radium- contaminated agents at Fernald, for example.
Perhaps references to the dial painter literature should be added or reasons
given for their omission.

There are many tables addressing the types of cancer outcomes and
affected organs, but only Table 1 mentions exposures. This is a generic
treatment of exposures to particular types of radiation (electron, photon, neutron,
etc). Could a list of exposures encountered at DOE sites be developed by type of
radionuclide? This might be useful to inform the reader as to the types of
radionuclides found at DOE facilities and to list the type of radiation each.of them
can produce. For example, radon not only produces alpha radiation, but gamma
and beta as well.

This naturally leads to my last comment on structure and policy issues in
the document. | did not find any detail on how multiple exposures to different
radionuclides or radiation types will be handled. On page 5, the document
indicates that doses will be calculated to any affected organ. It is not clear how
this will be done for different radiation types. For example, if someone with lung
cancer makes a claim with exposure to radon as well as some form of gamma
radiation, how will the lung dose be calculated? The document indicates that
exposure to radon decay products will be measured in WLM, which does not
lend itself to any precise lung dose without knowing a host of other factors. Some
additional details regarding multiple exposures and types of radiation would be
valuable.

My last few comments do not address the IREP structure per se, but
relate to some of the assumptions that underlie it.

Table 6 seems to indicate that smoking will only be considered for lung
cancer cases. Although lung cancer is the most common cancer associated with
cigarette smoking, it is well-established that several other cancers are related to
smoking. For example, cancers of the bladder, larynx, pharynx, and pancreas
have all been shown to be related to smoking. It seems unfair to single out only
lung cancer cases.

Some of the cancers on the list are not considered to be radiogenic and/or
there has been very little research relating radiation exposure to their incidence.
Given that a wider uncertainty interval could make the 99% percentile much
higher than the point estimate for PC, how will this affect compensation? Will
claims for these types of cancers actually be more likely to be awarded than
those for well-known radiogenic cancers? You probably already considered this,
but | felt the need to mention my concern.

A statement is made on page 14 that skin doses are well-estimated in the
A-bomb survivors studies. ! cannot imagine why skin dose estimates were better
than other doses estimated in the Japanese studies. Perhaps a comment could
be added to the document regarding this issue.

The inverse dose-rate effect for radon exposures is not considered by
IREP. The principal reason given is that the miners studies do not observe this