assessment (IDA) process for the Columbia River. The objective of the draft RAC report is to perform screening calculations that can be used to evaluate that recommendation.

Specifically, RAC was required by CDC to perform the following:

1. Review all the available HEDR Project documents related to the published Columbia River dose calculations and select the best available information related to the quantities of each of the eight radionuclides listed above that were released to the Columbia River between 1944 and 1972. The contractor shall NOT develop any new information on estimates of the radionuclide releases to the Columbia River without the approval of the project officer.

2. Review risk-based screening limits that could be used by CDC as decision criteria for choosing radionuclides for further consideration in the development of an IDA code for the Columbia River pathway.

3. Develop a screening method that accounts for all potential pathways of exposure for each of the eight radionuclides listed above. Organ-specific health risk, not just radiation dose, should be the end point of the screening calculations. All mathematical models and parameter values selected for use in the methodology should be carefully justified and thoroughly referenced.

4. After the screening method developed has been approved by the project officer, perform screening calculations for the eight radionuclides listed above. Screening calculations for a small number of additional radionuclides may be proposed, but no screening calculations will be performed for any additional radionuclides without the concurrence of the project officer.

5. As a result of the screening calculations, formulate for CDC’s consideration recommendations with regard to the inclusion of further radionuclides and pathways in future Columbia River individual dose calculations.”

The National Research Council’s committee was asked by CDC to address the following:

1. Has the screening method been carried out appropriately and completely?

2. Are the data sources assessed and used appropriately?

3. Is the environmental transport model presented in the report adequate and applicable for screening calculations for the Columbia River situation?

4. Are the exposure pathways complete and appropriate?

5. Are the screening risk estimates and associated uncertainties applied and presented adequately?

6. Are the discussion and conclusions of the results complete and reasonable?

At the initial meeting of the National Research Council’s committee in Washington, DC, on January 14, 2002, representatives of RAC—John Till, Helen Grogan, Edward Liebow, and Arthur Rood—were present. They enlarged on the draft report and the methods they used in arriving at the conclusions set forth in the report, and they responded to questions raised by the committee. Also present at the meeting were Charles Miller, chief of the Environmental

Letter Report (1-8)

List of Committee Members (9-9)

Appendix A: Specific Comments (10-25)

Appendix B: Quality Assurance and Quality Control (26-38)

References (39-40)