Risk-Based Screening for Releases to the Columbia River at Hanford

As part of the follow-up work to the Hanford Environmental Dose Reconstruction (HEDR) Study, the Centers for Disease Control and Prevention contracted with RAC to screen the radionuclides released to the Columbia River during operation of the Hanford Site from 1944-1972 on the basis of health risk. The purpose of the work was to check that the doses calculated in the HEDR Study for 24Na, 32P, 65Zn, 76As, and 239Np were the most important radionuclides released to the river, because a review for the Agency for Toxic Substance and Disease Registry suggested this was not the case and that doses from 131I, 60Co, and 90Sr should also be calculated.

RAC developed and applied a two-stage, risk-based screening methodology to identify the most important radionuclides and exposure pathways for releases to the Columbia River from the Hanford Site. This methodology was reviewed by the National Academy of Sciences. A key focus of this work was to investigate doses to Native Americans who use the Columbia River as a primary source of food (both now and historically). RAC used dietary information and habit data provided by Native American tribes in the region to accomplish this task.

The findings from this work confirmed that the HEDR Study calculated doses for the most important radionuclides, specifically 32P, 65Zn, 76As, and 239Np. Our analysis did not support the suggestion that doses from 131I and 90Sr needed to be calculated, but there was merit to the inclusion of 60Co as a secondary priority and also 95Zr and possibly 137Cs. Our findings were in agreement with the HEDR Study that fish ingestion was the dominant exposure pathway for releases to the Columbia River.

CDC TO7 Fact Sheet
CDC TO7 Final Report

Rocky Flats Soil Action Level Project

The Citizen’s Advisory Board at Rocky Flats selected RAC to derive soil action levels to be used as the basis for cleanup and decommissioning of the Rocky Flats Plant near Denver, Colorado. Over a period of 18 months in 1998 and 1999, RAC worked with the Radionuclide Soil Action Level Oversight Panel, which consisted of a mix of technical specialists and individuals with no technical experience drawn from public interest groups, local governments, and the general public. These panel members from a cross section of the community had considerable experience in Rocky Flats issues and were tasked with developing recommendations for soil cleanup.

Ultimately, these recommendations were used as the basis for cleanup at the site. Working with local citizens during the process helped the Department of Energy, the Environmental Protection Agency, and the Colorado Department of Public Health and Environment reach a unified approach to cleanup at the site, which has now been completed. The work was supported by the Rocky Flats Citizen’s Advisory Board.

RAC developed seven realistic scenarios, which served as guides to a range of possible profiles of people who may have been in the area. Working with the panel, RAC considered a number of key factors in the scientific calculation of the radionuclide soil action level (RSAL), including the impact of a fire on the area after cleanup, identifying the limiting scenario, and longevity of institutional controls.

The significant findings from this work included setting the RSAL for plutonium at 10 pCi/gram (370 Bq/kg) and for uranium at 20 pCi/gram (740 Bq/kg). RAC calculated the time of maximum dose for decision making purposes as 2000, the year following the RSAL calculations. The cost of cleanup and the impact of the actual cleanup phase on local residents were not taken into account. This was a public study and the oversight panel’s role was critical and unique in setting a technically-based soil action level.



Till, J.E., G. G. Killough, K. R. Meyer, J. W. Aanenson, and A.S. Rood. 2000. Calculating Soil Action Levels And Uncertainties for Decision-Making During Cleanup of Contaminated Sites. Proc of International Radiation Protection Association. IRPA-10 Plenary Session, PS-2-3, Hiroshima. May.

E. Till, G. G. Killough, K. R. Meyer, J. W. Aanenson, and A.S. Rood. 2004. “Technical Basis and Public Process for Deriving Cleanup Levels at Rocky Flats. Proc. Workshop on Solutions to Security Concerns about Radioactive Legacy of the Cold War that Remain in Urban Environments. International Institute for Applied System Analysis at Vanderbilt University. Nashville, TN. November 14-16, 2004

Assessment of Cerro Grande Fire

Following the Cerro Grande Fire in northern New Mexico in May 2000, the New Mexico Environment Department contracted RAC to perform an independent analysis of the health risks to the public from the fire burning within the boundary of the Los Alamos National Laboratory (LANL) in areas known or suspected to be contaminated with radionuclides and chemicals. The fire, which burned about 45,000 acres over 16 days, released chemicals and radionuclides from the burning and heating of material located in vegetation and soils across the LANL facility and the surrounding area. The work was performed in an open environment so different organizations and members of the public could provide input to and comments on the work as it progressed.

The findings from this work established that the primary health risk during the fire were associated with breathing material released into the air. RAC estimated the risk of cancer from breathing any LANL-derived chemical or radioactive material that may have been carried in the smoke plume to be less than 1 chance in 10 million. Potential exposure in the surrounding communities to LANL-derived chemicals that are not carcinogenic were about 10 times lower than acceptable intakes established by the U.S. Environmental Protection Agency.

Some evidence suggests that some adverse health effects did result from breathing high concentrations of particulate matter in the smoke. Such exposure are associated with any forest fire. Because vegetation was destroyed, the storm water flow through the canyons increased, carrying greater amounts of soil, sediment, and ash from the impacted areas.

Fact Sheet: Releases to Air
Fact Sheet: Releases to Surface Water
Summary Report

(Adobe PDFs)


Grogan, H.A., J.W. Aanenson, P.D. McGavran, K.R. Meyer, S.S. Mohler, H.J. Mohler, J.R. Rocco, and L.H. Wilson, and J.E. Till. 2006. “Applied Modeling of the Cerro Grande Fire at Los Alamos: An Independent Analysis of Exposure, Health Risk, and Communication with the Public.” In Applied Modelling and Computations in Nuclear Science, Oxford University Press. ACS Symposium Series 945. Edited by T.M. Semkow, S. Pommé, S.M. Jerome, and D.J. Strome. American Chemical Society, Washington, DC.


Calculated concentrations of PM10 (particulate matter