PUBLIC HEALTH ASSESSMENT Iodine-131 Releases Oak Ridge Reservation (USDOE) Oak Ridge, Anderson County, Tennessee EPA FACILITY ID: TN1890090003 March 2008 Prepared by: Site and Radiological Assessment Branch Division of Health Assessment and Consultation Agency for Toxic Substances and Disease Registry Evaluation of Iodine-131 Releases from the Oak Ridge Reservation Public Health Assessment Foreword The Agency for Toxic Substances and Disease Registry, ATSDR, is an agency of the U.S. Department of Health and Human Services. ATSDR was established by Congress in 1980 under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as the Superfund Law. This law set up a fund to identify and clean up our country’s hazardous waste areas. The U.S. Environmental Protection Agency (EPA) and the individual states regulate the investigation and clean up of the areas. Since 1986, ATSDR has been required by law to conduct a public health assessment at each of the areas on the EPA National Priorities List. The aim of these evaluations is to find out if people are being exposed to hazardous substances and if so, whether that exposure is harmful and should be stopped or reduced. If appropriate, ATSDR also conducts public health assessments when petitioned by concerned individuals. Public health assessments are carried out by environmental and health scientists from ATSDR and from the states with which ATSDR has cooperative agreements. Exposure: As the first step in the evaluation, ATSDR scientists review environmental data to determine the level of contamination at an area, where it is, and how people might come into contact with it. In general, ATSDR does not collect its own environmental sampling data; rather, it reviews information provided by EPA, other government agencies, businesses, and the public. When there is insufficient environmental information, the report will indicate what additional sampling data are needed. Health effects: If the review of the data shows that people have or could come into contact with hazardous substances, ATSDR then evaluates whether or not there are likely to be any harmful effects from these exposures. The report focuses on the health impact on the community as a whole, rather than on risks to individuals. ATSDR generally uses existing scientific information, which can include the results of medical, toxicological, and epidemiological studies, and the data collected in disease registries. The science of environmental health is still developing, and occasionally scientific information on the health effects of certain substances is not available. When this is so, the report will suggest what further research studies are needed. Conclusions: The report presents conclusions about the level of health threat, if any, posed by an area. In its public health action plan, the report recommends ways to stop or reduce exposure. ATSDR is primarily an advisory agency, so these reports usually identify what appropriate actions are to be undertaken by EPA, other responsible parties, or the research or education divisions of ATSDR. However, if there is an urgent health threat, ATSDR can issue a public health advisory to warn people of the danger. ATSDR can also authorize health education or pilot studies of health effects, full-scale epidemiological studies, disease registries, surveillance studies, or research on specific hazardous substances. Community: ATSDR also needs to learn what local people know about an area and what concerns they may have about the impact on their health. Consequently, throughout the evaluation process ATSDR actively gathers information and comments from people who live or work near an area, including residents, civic leaders, health professionals, and community groups. To ensure that the report responds to the community’s health concerns, an early version i is also distributed to the public for comment. ATSDR responds to all comments received from the public in the final version of the report. Comments If you have questions or comments after reading this report, we encourage you to send them to us. Letters should be addressed as follows: Manager, ATSDR Records Center Agency for Toxic Substances and Disease Registry 4770 Buford Highway NE F-09 Atlanta, GA 30341-3717 ii Evaluation of Iodine-131 Releases from the Oak Ridge Reservation Public Health Assessment Table of contents I. Summary ..................................................................................................................................1 I.A. Oak Ridge Reservation background.................................................................................1 I.B. Agency for Toxic Substances and Disease Registry’s (ATSDR’s) evaluation of past, current, and future exposure to radioactive iodines ................................................1 II. Background ..............................................................................................................................4 II.A. Description and operational history .................................................................................4 II.B. Demographics and land use of the Oak Ridge area .........................................................9 II.C. ATSDR’s involvement and other health activities at ORR............................................12 III. Exposure pathway evaluation ................................................................................................13 III.A. Introduction ....................................................................................................................13 III.B. Air exposure pathway.....................................................................................................15 IV. Public health implications......................................................................................................37 IV.A. Toxicological implications of iodine exposure ..............................................................37 IV.B. Radiological aspects of iodine dosimetry.......................................................................38 V. Community health concerns ..................................................................................................45 VI. Conclusions............................................................................................................................74 VI.A. Past exposure..................................................................................................................74 VI.B. Current and future exposure...........................................................................................75 VII. Recommendations..................................................................................................................76 VIII. Public health actions.............................................................................................................77 IX. Authors ................................................................................................................................78 X. References..............................................................................................................................79 Appendix A. ATSDR glossary of environmental health terms................................................ A-1 Appendix B. A conservative approach to radiation dose assessment .......................................B-1 Appendix C. Implications of exposure to radioactive iodines from ORNL..............................C-1 Appendix D. Responses to peer reviewer comments on iodine 131 releases public health assessment........................................................................................................... D-1 Appendix E. Responses to public comments on iodine 131 releases public health assessment............................................................................................................E-1 iii List of tables Table 1. Estimated maximum annual radioactive iodine release by source area............................ 5 Table 2. Estimated amount of I-131 released from RaLa processing, 1944–1956....................... 16 Table 3. Annual Dispersion Concentrations of I-131 at Ground Level, 1967–1969.................... 17 Table 4. Task 1 reference diets ..................................................................................................... 19 Table 5. Average long-term gross beta and gamma activity at onsite locations........................... 28 Table 6. Average long-term gross beta and gamma activity at Rock Quarry, ORR perimeter, and distant off-site locations, 1956 ........................................................................................ 31 Table 7. Annual limits on intakes for workers exposed to radioactive iodines* .......................... 39 Table 8. ICRP data for the biological kinetics of iodine............................................................... 39 List of figures Figure 1. Radioactive lanthanum (RaLa) processing at the ORR X-10 site................................... 7 Figure 2. RaLa process components ............................................................................................... 8 Figure 3. Demographics surrounding ORNL................................................................................ 11 Figure 4. ORR areas studied for I-131 releases from the RaLa facility, 1944–1956 ................... 20 Figure 5. Upper 97.5% range of iodine release concentrations in air from RaLa ........................ 22 Figure 6. Range of dose to the