Federal radiation protection guidance is developed by the Administrator of the Environmental Protection Agency as part of his or her responsibility, under Executive Order 10831, to "... advise the President with respect to radiation matters, directly or indirectly affecting health, including guidance for all Federal agencies in the formulation of radiation standards and in the establishment and execution of programs of cooperation with States." The purpose of Federal guidance is to provide a common framework to ensure that the regulation of exposure to ionizing radiation is carried out in a consistent and adequately protective manner.
This Federal guidance report is the third of a series designed to provide technical information useful in implementing radiation protection programs. It is our hope that it will help ensure that regulation of exposure to radiation is carried out in a consistent manner that makes use of the best available information for relating concentrations of radioisotopes in environmental media to dose in human populations due to external radiation. The dose coefficients in this report are intended for use by Federal agencies having regulatory responsibilities for protection of members of the public and/or workers, such as the Environmental Protection Agency, the Nuclear Regulatory Commission, and Occupational Health and Safety Administration, as well as by those Federal agencies with responsibilities related to the management of their own and their contractor operations, such as the Department of Energy and the Department of Defense. We also encourage their use by State and local authorities.
Exposure to external radiation from contaminated soil, which is a central focus of the calculations carried out to produce this report, is a particularly timely subject. The Nation is at the beginning of perhaps the largest cleanup operation in its history, at the large collection of sites involved in the development of nuclear weapons and commercial nuclear power during the past half century. An accurate assessment of this exposure pathway is essential to the decisions that will be required to regulate, manage, and verify this cleanup.
The principal dose quantity, effective dose equivalent, has been calculated with the weighting factors used in Federal Guidance Report No. 11, which were those recommended in Radiation Protection Guidance to Federal Agencies for Occupational Exposure (EPA, 1987). New estimates of radiation risk to the organs and tissues have been published since then (UNSCEAR, 1988; NAS, 1990) and updated weighting factors have been recommended by the International Commission on Radiological Protection (ICRP, 1991). However, new weighting factors have not yet been adopted for use in the United States and would require a number of adjustments to existing regulations. As the report notes, for most radionuclides these dose coefficients are not very sensitive to the choice of weighting factors. We are reviewing new weighting factors, as well as EPA's own estimates of organ-specific risk factors, and we will propose changes in the weighting factors as soon as it appears necessary and reasonable to do so. At that time, we will also publish revised versions of this report and of Federal Guidance Report No. 11.
The tables in this report are also available as computer files so that they may be more easily used in programs for assessing dose. We are simultaneously making the tables for internal exposure contained in Federal Guidance Report No. 11 available in the same format. Instructions for obtaining both of these sets of computer files may be found at the back of this report.
We gratefully acknowledge the work of the authors, Keith F. Eckerman and Jeffrey C. Ryman, without whose outstanding contributions over the past several decades tables such as these would not exist. This project was made possible through joint funding from three Federal agencies: the Department of Energy (DOE), the Nuclear Regulatory Commission (NRC), and the Environmental Protection Agency. We appreciate the consistent support of the DOE and NRC project officers, C. Welty and N. Varma, and S Yaniv and R. Meck, respectively, throughout the lengthy term of this work. We are also indebted to H. Beck, S. Y. Chen, C. M. Eisenhauer, P. Jacob, G. D. Kerr, D. C. Kocher, and C. B. Nelson for their technical reviews. The report has been clarified and strengthened through their efforts. We would appreciate being informed of any errors or suggestions for improvements so that these may be taken into account in future editions. Comments should be addressed to Allan C. B. Richardson, Deputy Director for Federal Guidance, Criteria and Standards Division (6602J), U. S. Environmental Protection Agency, Washington, DC 20460.