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EXECUTIVE SUMMARY The National Research Council was asked by the Centers for Disease Control and Prevention (CDC) to review the draft report of the National Cancer Institute (NCI)-CDC's working group charged with revising the 1985 radioepidemiological tables. To this end, a subcommittee was formed consisting of members of the Council's Committee on an Assessment of the Centers for Disease Control and Prevention Radiation Programs and other experts. The original tables were mandated under Public Law 97-414 (the "Orphan Drug Act") and were intended to provide a means of estimating the probability that a person who developed any of a series of radiation-related cancers, developed the cancer as a result of a specific radiation dose received before the onset of the cancer. The mandate included a provision for periodic updating of the tables. The motivation for the current revision reflects the availability of new data, especially on cancer incidence, and new methods of analysis, and the need for a more thorough treatment of uncertainty in the estimates than was attempted in the original tables. The subcommittee discusses this point in more detail in section 1 0. . , The working group has chosen to replace the 1985 tables with an interactive computer program Interactive Radio-Epidemiological Program (IREP)~. Their stated aim has been to provide agencies and individuals with a means of computing estimates of cancer risk after exposure to radiation that reflect the circumstances of an individual compensation claim better than was possible with the original tables and of ascertaining the statistical uncertainty inherent in a particular estimate of radiation-related assigned shares. The subcommittee believes that this approach provides a broader coverage of cancer sites of potential interest to individual claimants , ~ . _ ~ .~ ~ ~ ~ .~ ~ ~~ . . ~ ~ ~ ,~ , ,~ ' ~ 1 1 1~ ~ _ than did the 1YS5 tables, and that the accompanying computer program COU1d nave wide applicability. The working group deserves considerable praise for its efforts, not only with regard to the specific mandate, but also with regard to a broader understanding of the policy context of the mandate. The interactive software offers many advantages over the tables that it supplements, and there has clearly been careful thought regarding IREP's implementation. However, considerable development work will be needed before this product will be suitable for any but highly specialized audiences. Although the subcommittee endorses the working group's approach, in part because of its greater flexibility, we do not believe that a computer program should replace the printed tables; the latter are potentially more useful to members of minority groups and economically disadvantaged groups who do not have access to computers. The subcommittee concludes that the working group has done an excellent job of selecting data sources on which to base its model of assigned shares and has made reasonable judgments in selecting values of the model parameters and characterizing their uncertainties. However, The calculated probabilities pertain to populations rather than individuals and as such are not probabilities in the I hilt Are nronertieS of the group to which a person belongs. These probabilities are assigned to a person for the purposes of compensation, and the term assigned share is used to emphasize the difference. ~ -A ~ r--r 1

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there is a need to clarify the sources of infonnation on uncertainty with regard to the relative biological effectiveness of various qualities of radiation, the dose and dose-rate effectiveness factor, and the miscellaneous other factors that possibly influence nsk. More thought should be given to the inclusion in the mode] of a systematic risk factor for persons with known genetic radiosensitivity predispositions. Moreover, the subcommittee was concerned about the problems with including so many cancer sites for which radiation associations have not been well established. In such circumstances, subjective confidence intervals can be very wide and could lead to a situation in which compensation is awarded under dubious conditions of causation while a scientifically stronger case with a narrow confidence interval fails. The validity of this approach should be carefully considered. The subcommittee further recommends that the working group clearly describe and discuss in the report the changes in risk estimates and uncertainty ranges from the 1985 to the 2000 tables and the likely impact of these changes on compensation claims. 2