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Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials (1999)

Chapter: 7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides

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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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Suggested Citation:"7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides." National Research Council. 1999. Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials. Washington, DC: The National Academies Press. doi: 10.17226/6360.
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7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides The primary purpose of this chapter is to review existing and proposed Environmental Protection Agency (EPA) guidances and regulations that apply to control of routine exposures of the public to naturally occurring radionuclides. As discussed in chapter 2, the naturally occurring radionuclides of primary concern in radiation protection of the public include isotopes of uranium, thorium, and radium and their radiologically important shorter-lived decay products. EPA guidances and regulations reviewed in this chapter include those that apply either to TENORM or to naturally occurring radionuclides associated with operations of the nuclear fuel cycle, which are not included in TENORM as defined in this study. No distinction is made in this review between TENORM and NORM associated with the nuclear fuel cycle because the intent is to indicate the variety of approaches used by EPA in regulating naturally occurring radionuclides for any exposure situations of concern. In chapter 10, EPA guidances and regulations that apply specifically to TENORM are summarized and compared with guidances for TENORS developed by other organizations. The guidances and regulations considered in this review apply only to situations in which routine exposures to naturally occurring radionuclides are affected by human activities; they do not apply to naturally occurring radionuclides in their undisturbed state. This review is not concerned with EPA guidances on control of radiation exposures in the workplace (EPA 1987a) or responses to accidental releases of radionuclides to the environment (EPA 1992a). EPA's guidances and regulations that apply to control of routine exposures of the public to naturally occurring radionuclides may be divided into two categories: 106

GUIDANCES AND REGULATIONS FOR NORM · Guidance on radiation protection of the public, which applies to all specified controlled sources of exposure combined. . practices. Guidance or regulations that apply only to specific sources or 107 This review of EPA guidances and regulations emphasizes the quantitative criteria that apply to naturally occurring radionuclides and the basis for these criteria. In addition to the specific guidances and regulations, this chapter discusses the health risks to the public that correspond to the quantitative criteria in different guidances and regulations, the important issue of consistency of standards in regard to limits on risk, and the relationship between the quantitative criteria in the various guidances and regulations and the doses or risks experienced in actual exposure situations. GUIDANCE ON RADIATION PROTECTION OF THE PUBLIC EPA is responsible for developing guidance for all federal agencies on standards for radiation protection of the public. These standards apply to all specified controlled sources of exposure combined, excluding indoor radon, but do not apply to natural background radiation and to beneficial medical exposures. EPA has issued proposed federal guidance on radiation protection of the public (EPA 1994d) to replace the guidance developed many years ago by the Federal Radiation Council (FRC 1961; 1960~. Although the proposed guidance has not been issued in final form, the committee has assumed that it represents EPA's current views on the basic, minimal requirements for radiation protection of the public. Therefore, the proposed guidance is given greater emphasis in this study than the existing FRC guidance. EPA's proposed federal guidance on radiation protection of the public includes the following provisions of interest to this study: . There should be no radiation exposure of the general public unless it is justified by the expectation of an overall benefit from the activity causing the exposure. · Doses to individuals and populations should be as low as reasonably achievable (ALARA).

108 GUIDELINES FOR EXPOSURE TO TENORM . The annual effective dose equivalent to individuals from all controlled sources combined, including sources not associated with operations of the nuclear-fuel cycle but excluding indoor radon, should not normally exceed 1 mSv (100 mrem). · Annual effective dose equivalents to individuals up to 5 mSv (500 mrem) may be permitted, with prior authorization, in unusual, temporary situations. · Continued exposure over substantial portions of a lifetime at or near 1 mSv (100 mrem) per year should be avoided. · Authorized limits for specific sources or practices should be established to ensure that the primary dose limit of 1 mSv (100 mrem) per year for all controlled sources combined and the ALARA objective are satisfied, and the authorized limit for any source or practice normally should be a fraction of the dose limit for all controlled sources combined. The provisions listed above would apply to naturally occurring radionuclides, including TENORM, other than indoor radon, whenever exposures of the public are affected by human activities. However, to ensure compliance with these provisions, especially the primary dose limit for all sources of exposure combined, exposures to human-made radionuclides also would need to be taken into account. EPA's proposed federal guidance was based in large part on recommendations on radiation protection of the public developed previously by the International Commission on Radiological Protection (ICRP 1977) and the National Council on Radiation Protection and Measurements (NCRP 1987c). In addition, the emphasis in the proposed guidance on the use of authorized limits for specific sources or practices at a fraction of the primary dose limit for all sources of exposure combined, to help ensure compliance with the primary dose limit and the ALARA objective, conforms to current recommendations of ICRP (1991) and NCRP (1993a). The existing federal guidance on radiation protection of the public (FRC 1961; 1960), which EPA's proposed guidance would replace, includes the following provisions of interest to this study: · There should not be any exposure to human-made radiation without the expectation of benefit from such exposure.

GUIDANCES AND REGULATIONS FOR NORM . Every effort should be made to encourage keeping radiation doses as far below recommended limits as practicable. · For external exposure, the annual dose equivalent to the whole body of individuals should not exceed 5 mSv (500 mrem), and the dose equivalent to the gonads for average individuals in exposed populations should not exceed 50 mSv (5,000 mrem) in 30 y, that is, an average annual dose of 1.7 mSv (170 mrem). · For internal exposure, the annual dose equivalent to individuals should not exceed 5 mSv (500 mrem) to bone marrow and 15 mSv (1,500 mrem) to bone or the thyroid, and the annual dose equivalents to these organs for average individuals in exposed populations should not exceed one-third of these values. 109 EPA's proposed federal guidance on radiation protection of the public differs from the existing FRC guidance in several important respects. First, the proposed guidance is explicit that it would apply to all controlled sources of exposure combined (except as noted), including sources not associated with operations of the nuclear fuel cycle. The existing FRC guidance is not explicit on this point and has not been applied consistently to sources not associated with operations of the nuclear fuel cycle, especially to important sources of exposure to TENORM (EPA 1 994d). Second, the existing FRC guidance specifies dose limits for the whole body and the critical organ, and separate dose limits are specified for external and internal exposure. The proposed guidance would replace the dose limits for the whole body and the critical organ and the separate dose limits for external and internal exposure with a single limit on effective dose equivalent from external and internal exposure combined. The effective dose equivalent is intended to be proportional to stochastic risk posed by any exposure without regard for the distribution of doses among different organs or tissues. Third, in most cases, the limit on annual effective dose equivalent of 1 mSv (100 mrem) in the proposed guidance is expected to correspond to lower allowable exposures than the existing FRC guidance on dose limits for the whole body or the critical organ from either external or internal exposure. The reduction in the maximum allowable exposures was based on information on the risk per unit dose that was not available when the FRC guidance was developed and on a judgment about an upper bound on acceptable risk posed by exposure to all controlled sources combined (see chapter 5~. Finally, the separate dose limit for the gonads of average individuals in the FRC guidance, which was intended to limit the induction of severe genetic effects in exposed populations, would no longer be specified. In the proposed

110 GUIDELINES FOR EXPOSURE TO TENORM guidance, the genetic risk would be taken into account in the weighting factor for the gonads used in defining the effective dose equivalent (ICRP 1977~. The essential purpose of EPA's proposed federal guidance on radiation protection of the public is to limit incremental health risks to exposed individuals and populations to levels that society generally regards as acceptable. In selecting the primary dose limit of 1 mSv (100 mrem) per year from exposure to all controlled sources combined, EPA considered several judgmental factors. These factors included the lifetime risk corresponding to the limit on annual dose, the degree of additional protection that would be achieved by the application of ALARA by regulatory authorities for specific sources or practices and by the consideration of the possibilities for multiple exposures to current and future sources, and the record on the operational application of the ALARA objective in reducing actual doses to levels below authorized limits (EPA 1994d). The lifetime risk corresponding to the primary dose limit of 1 mSv (100 mrem) per year can be estimated by assuming continuous exposure over 70 y at the dose limit and a risk of fatal cancers per unit dose for members of the public of S x 10-s per millisievert (S x 10-7 per millirem) (EPA 1994c; NCRP 1993a; ICRP 1991~. On the basis of those assumptions, the lifetime risk of fatal cancers would be about 4 x 10-3. This value is somewhat higher than the lifetime risk of about 10-3 that ICRP (1977) judged to be an upper bound on acceptable risk posed by radiation exposure on the basis of data on other involuntary risks that the public has accepted in everyday life (see chapter 5~. However, as emphasized in the proposed federal guidance (EPA 1994d), compliance with the primary dose limit of 1 mSv (100 mrem) per year does not, by itself, provide acceptable radiation protection of the public; compliance with the ALARA objective also is a central tenet of radiation protection. Indeed, as a result of the establishment of authorized limits for specific sources or practices at a fraction of the primary dose limit and further vigorous application of the ALARA objective at specific sites, the average annual effective dose equivalent to individuals in exposed populations within 80 km (SO miles) of operating nuclear facilities is only about 0.5 ,uSv (0.05 mrem) (NCRP 1987a). That dose corresponds to a lifetime risk of fatal cancers of only about 2 x 10-6, or lower by a factor of 2,000 than the risk corresponding to the primary dose limit. Furthermore, doses to individuals receiving the highest exposures, although they might substantially exceed the average dose in exposed populations, normally are only about 10% of the primary dose limit or less (EPA 1989d). Thus, although the purpose of the proposed federal guidance is to limit risks posed by radiation exposure, an acceptable risk is not defined by the primary dose limit alone. For most exposure situations, the acceptability of risks is defined primarily by application of the ALARA objective, which involves

GUIDANCES AND REGULATIONS FOR NORM 111 judgments about doses to individuals and populations that are reasonably achievable for specific sources or practices and at specific sites. Even though compliance with the ALARA objective can be defined to some extent by authorized limits for specific sources or practices at a fraction of the primary dose limit, application of the objective at each site is a process, not a result that can be specified a priori in regulations. An additional factor taken into account by EPA in judging that the primary dose limit of 1 mSv (100 mrem) per year and reductions in dose below the limit to meet the ALARA objective would provide acceptable risks to individuals and populations was the unavoidable risk posed by exposure to natural background radiation. The average effective dose equivalent from all natural sources including cosmic rays, cosmogonic and terrestrial radionuclides, radionuclides in the body, and indoor radon is about 3 mSv (300 mrem) per year in the United States (see table 2.10~. The primary dose limit proposed by EPA thus corresponds to about one-third of the average dose from natural background radiation, for which the estimated lifetime risk of fatal cancers is about 10-2. Although the average dose from exposure to natural background does not provide a justification for the primary dose limit for all controlled sources combined, it does provide a perspective for judging whether the dose limit for all controlled sources is reasonable (see chapter 5~. GUIDANCE AND REGULATIONS FOR SPECIFIC SOURCES OR PRACTICES EPA is authorized under several environmental laws to establish guidance or regulations for controlling radiation exposures of the public to specific sources or practices (see chapter 6~. As noted in the previous section, authorized limits for specific sources or practices (also called source constraints or dose constraints) are an important means of ensuring compliance with the primary dose limit for all controlled sources combined and the ALARA objective in radiation-protection standards for the public. EPA's guidances and regulations for specific sources or practices can be divided into the following categories (the legal authority for establishing guidance or regulations in each category is given in parentheses): · Operations of uranium fuel-cycle facilities (Atomic Energy Act). · Radioactivity in drinking water (Safe Drinking Water Act). · Radioactivity in liquid discharges (Clean Water Act).

112 GUIDELINES FOR EXPOSURE TO TENORM · Uranium and thorium mill tailings (Uranium Mill Tailings Radiation Control Act; Atomic Energy Act). · Radioactive waste management and disposal (Atomic Energy Act). · Remediation of radioactively contaminated sites (Comprehensive Environmental Response, Compensation, and Liability Act, CERCLA; Atomic Energy Act). · Airborne emissions of radionuclides (Clean Air Act). · Indoor radon (Indoor Radon Abatement Act). In addition, EPA may, under the Toxic Substances Control Act (TSCA), regulate naturally occurring and accelerator-produced radioactive materials (NARNI), including TENORS, which are not subject to regulation under the Atomic Energy Act; and NARM wastes also could be regulated under the Resource Conservation and Recovery Act (RCRA). EPA has not developed proposed regulations specifically for NARM under either TSCA or RCRA. The following sections review existing or proposed guidances and regulations for specific sources or practices developed by EPA Mat apply to naturally occurring radionuclides. The relevant quantitative criteria in the guidances and regulations are presented, and the bases for the criteria are discussed. The criteria that apply to naturally occurring radionuclides, including EPA's proposed federal guidance on radiation protection of the public discussed above, also are summarized in table 7.1. After He discussions of the guidances and regulations, the possibility of regulating NARM under TSCA or RCRA is discussed.

G UIDANCES AND BEG ULA TIONS FOR NOW Table 7.1. Summary of EPA guidances and regulations applicable to naturally occurring radionuclidesa 113 Guidance or regulation Quantitative criteriab = Proposed federal Annual effective dose equivalent guidance on radiation of 1 mSv protection of the public (EPA 1994d)C Standards for operations Annual dose equivalent of of uranium fuel-cycle 0.25 mSv to whole body, facilities (40 CFR Part 0.75 mSv to thyroid, and 190) 0.25 mSv to any other organ Interim standards for Concentration of 5 pCi/L for radioactivity in 226Ra plus 228Ra~ community drinking water systems (40 CFR Concentration of 15 pCi/L for Part 141) gross alpha-particle activity, including 226Ra but excluding radon and uraniums Proposed revisions of Concentration of 20 pCi/L for interim standards for 226Ra and 228Ra separately radioactivity in community drinking- Concentration of 20 ~g/L for water systems (EPA uranium 1997; 1991a) Concentration of 15 pCi/L for gross alpha-particle activity, excluding 226Ra, uranium, and 222Rnd Annual effective dose equivalent of 0.04 mSv from all beta- or gamma-emitting radionuclides, excluding 228Ra Comments Dose limit applies to all controlled sources of exposure combined, excluding indoor radon and beneficial medical exposures. Based on considerations of maximum tolerable risk to individuals and ability of authorized limits for specific sources or practices and further application of ALARA objective to reduce doses well below limit. Based primarily on doses judged reasonably achievable with available effluent-control technologies. Based primarily on cost- benefit analysis for reducing existing levels of naturally occurring radionuclides in drinking water. Based primarily on revised cost-benefit analysis for reducing existing levels of naturally occurring radionuclides in drinking water.

4 Table 7.1. (continued) GUIDELINES FOR EXPOSURE TO TENORM Guidance or regulation Quantitative criteria Comments Standards for Concentrations in daily effluents radioactivity in liquid of 10 pCi/L for dissolved 226Ra, discharges (40 CFR Part 30 pCi/L for total 226Ra, and 440) 4 mg/L for uraniums Average concentrations in daily effluents over 30 d of 3 pCi/L for dissolved 226Ra, 10 pCi/L for total 226Ra, and 2 mg/L for uraniums Standards for uranium or Annual average release rate of thorium mill tailings (40 222Rn to air of 20 pCi/m2 per CFR Part 192) second or concentration of 222Rn in air outside disposal site of 0.5 pCi/L Average concentrations of 226Ra in soil above background over any area of 100 m2 of 5 pCi/g in top 15 cm or 15 pCi/g below 15 cm Concentration of radon decay products indoors including background of 0.03 WL, with objective of 0.02 WLe Indoor gamma radiation level above background of 20 ,uR/hf Concentrations in groundwater of 5 pCi/L for 226Ra plus 228Ra, 15 pCi/L for gross alpha-particle activity, and 30 pCi/L for 234U plus 23sU~ Annual dose equivalent from thorium-processing operations as in uranium fuel-cycle standards (40 CFR Part 190) Limits apply to liquid discharges from mines or mills used to produce or process uranium, radium, or vanadium ores. Based primarily on available effluent- control technologies. Releases during uranium- processing operations and from uranium mill tailings disposal sites before end of closure period must comply with dose constraint in 40 CFR Part 190 and concentration limits for liquid discharges in 40 CFR Part 440. Based primarily on background levels of radioactivity in western United States and objective of reducing exposures of the public to as close to background levels as reasonably achievable; groundwater-protection requirements are based on current and proposed drinking-water standards (40 CFR Part 141).

GUIDANCES AND HULA TIONS FOR NOW Table 7.1. (continued) 115 Guidance or regulation Quantitative criteria Comments Standards for 1~ ta: ~ cs m~u n~ be I management and storage Nuclear Regulatory Commission of spent fuel, high-level or Agreement States, annual dose waste, and transuranic equivalent of 0.25 mSv to whole waste (40 CFR Part 191 ) body, 0.75 mSv to thyroid, and 0.25 mSv to any other organ For DOE facilities not regulated by Nuclear Regulatory Commission or Agreement States, annual dose equivalent of 0.25 mSv to whole body and 0.75 mSv to any organ Standards for disposal of Cumulative releases to accessible spent fuel, high-level environment per 1,000 MTHM waste, and transuranic of 100 Ci for 226Ra 234U 23sU waste (40 CFR and 238U 10 Ci for 230Th and , Part 191)8 232Th; and 1,000 Ci for 2l0Pbh Annual effective dose equivalent in accessible environment from all exposure pathways of 0.15 mSv' Levels of radioactivity in underground sources of drinking water in accessible environment as specified by MCLs in drinking-water standards (40 CFR Part 141 )' Standards for cleanup of Goal of compliance with radioactively ARARs, TBCs, and lifetime contaminated sites cancer risk of 10~; limits that (CERCLA and 40 CFR must be achieved by cleanups Part 300) without regard for other factors are not specified Based primarily on doses judged reasonably achievable with available effluent-control technologies; dose constraint is consistent with uranium fuel-cycle standards (40 CFR Part 190). Cumulative release limits were based on 1,000 health effects in US population, which was judged reasonably achievable. Dose constraint for individuals was based on judgment about acceptability of risk and feasibility of achieving specified dose. Groundwater protection requirement was based on general strategy of protecting resource consistent with current drinking-water standards. Based on goal of complying with relevant requirements under other environmental laws and achieving consistency with cancer risks corresponding to other laws and regulations (such as Safe Drinking Water Act and Clean Air Act).

116 Table 7.1. (continued) GUIDELINES FOR EXPOSURE TO TENORM Guidance or regulation ! Quantitative criteria T Comments i| Standards for airborne Annual effective dose equivalent emissions of of 0.1 mSv for many DOE and radionuclides (40 CFR non-DOE federal facilities, but Part 61) excluding dose from 222Rn and its decay products, and for emissions of 222Rn from underground uranium mines Annual emissions of deco from elemental phosphorus plants of 2 or 4.5 Cih Emission rate of 222Rn from specified radium-bearing materials of 20 pCi/m2 per seconds Guidance on radon in Mitigation for radon homes (EPA and DHHS concentrations above 4 pCi/L~ 1994) Mitigation for radon concentrations of 2-4 pCi/L if ] concentrations can be reduced below 2 pCi/L~ aGuidances or regulations that do not specifically apply only to naturally occurring radionuclides apply to human-made and naturally occurring radionuclides combined. Guidances or regulations that apply only to human-made radionuclides are not given in the table. bCriteria expressed in terms of dose equivalent apply to individual members of the public. Criteria expressed in terms of quantities other than dose are given in the units presented in the guidance or Based primarily on lifetime cancer risk to maximally exposed individuals of 104 and average lifetime risk in exposed populations of 10-6. Based on protection of individuals receiving highest exposures and cost-benefit analysis for reducing existing levels of rar1nn in hc)meq regulation, and the conversion to SI units is indicated in a footnote. CProposed guidance would replace existing guidance of Federal Radiation Council (FRC 1961 1960), which essentially specifies limit on annual dose equivalent of 5 mSv. 41 psi = 0.037 Bq. el Working Level (WL) = 2.08 x 10-s J/m3. fl R= 2.58 x 10~ C/kg. "Standards apply for 10,000 years after disposal. hi Ci = 0.037 TBq. Standard applies only to undisturbed performance of disposal system (that is, absent human intrusion). 1 ;

GUIDANCES AND REGULATIONS FOR NORM Standards for Operations of Uranium Fuel Cycle 117 EPA's current standards for operations of uranium fuel-cycle facilities in 40 CFR Part 190 were established in 1977 (42 FR 28584.4 They apply to normal operations in the milling of uranium ore, chemical conversion of uranium, isotopic enrichment of uranium, fabrication of uranium fuel, electricity generation in light-water-cooled nuclear power plants using uranium fuel, and reprocessing of spent uranium fuel, but not to mining operations, transportation of radioactive material, operations at waste-disposal sites, and reuse of recovered non-uranium special nuclear material and byproduct materials as defined in the Atomic Energy Act. The particular standard that applies to releases of naturally occurring radionuclides is a constraint on annual dose equivalent to individuals from all radionuclides, except radon and its decay products, of: · 0.25 mSv (25 mrem) to the whole body. · 0.75 mSv (75 mrem) to the thyroid. . 0.25 mSv (25 mrem) to any other organ. Separate activity limits on releases of some longer-lived, human-made radionuclides also are specified, but such limits are not specified for any naturally occurring radionuclides. The dose constraint in the uranium fuel-cycle standards given above is essentially 5% of the primary whole-body dose limit of 5 mSv (500 mrem) per year for exposure to all controlled sources combined in the existing FRC guidance discussed earlier. However, the dose constraint in the fuel-cycle standards was based not on a judgment that doses at these levels were necessary to achieve acceptable health risks to the public, but primarily on a judgment that the specified doses were reasonably achievable with available effluent-control technologies. Thus, the standard essentially represents an application of the ALARA objective to standard-setting itself. An additional factor in establishing 4Title 40 of the Code of Federal Regulations (CFR), published annually by the US Government Printing Office, contains all EPA regulations. For each regulation published in the CFR, reference to the Federal Register (FR) notice containing the promulgated regulation is given; these notices provide supplementary information on the basis for the regulations.

118 GUIDELINES FOR EXPOSURE TO TENORM the dose constraint was that the corresponding levels of radioactivity in the environment should be readily measurable (see chapter 5~. In the time since EPA's uranium fuel-cycle standards were promulgated, an authorized limit of 0.25 mSv (25 mrem) per year has been incorporated in other EPA standards for specific sources or practices, as well as in standards for low-level waste disposal established by the Nuclear Regulatory Commission (1982a) and the Department of Energy (DOE 1988~. Furthermore, on the basis of the currently accepted risk per unit dose of 5 x 10-5 per rn~llisievert and an assumption that the lifetime risk posed by exposure to all controlled sources combined should not exceed about 10-3, an authorized limit of 0.25 mSv (25 mrem) per year for specific human-made sources is now widely regarded as necessary for protection of public health (for example, NCRP 1993a). Thus, a dose constraint of 0.25 mSv (25 mrem) per year for specific sources or practices has attained an importance for radiation protection of the public considerably beyond its original use in the uranium fuel-cycle standards. Standards for Radioactivity in Drinking Water EPA's current (interim) standards for radioactivity in community drinking-water systems in 40 CFR Part 141 were established in 1976 (41 FR 28404~. They are concerned primarily with exposures to naturally occurring radionuclides, principally radium, and they apply at the tap rather than at the source. The current drinking-water standards that apply to naturally occurring radionuclides include concentration limits of: · 0.2 Bq/L (5 pCi/L) for radium-226 plus radium-228. · 0.6 Bq/L (15 pCi/L) for gross alpha-particle activity, including 226Ra but excluding radon and uranium. The standards for naturally occurring radionuclides are expressed in terms of concentration rather than dose to individuals to allow compliance to be monitored by operators of water systems. The interim standards also include a dose constraint of 0.04 mSv (4 mrem) per year to the whole body or any organ for human-made, beta- or gamma-emitting radionuclides, but this standard does not apply to any naturally occurring radionuclides. The drinking-water standards for radionuclides were developed in accordance with requirements of the Safe Drinking Water Act. The act requires, first, that EPA establish maximum contaminant level goals (MCLGs), which are

GUIDANCES AND REGULATIONS FOR NOW 119 nonenforceable health goals that must be set at levels where no known or anticipated health effects would occur and an adequate margin of safety for protecting public health is provided. For known carcinogens, including radionuclides, the MCLGs must be set at zero on the basis of the usual assumption, for purposes of risk management, of a linear, no-threshold dose- response relationship. The act then requires that EPA establish maximum contaminant-levels (MCLs) for drinking water. The MCLs are legally enforceable standards that must be set as close to the MCLGs as possible with technical feasibility and cost taken into account. Therefore, particularly for radium, which was regarded as the most important naturally occurring radionuclide in drinking water, EPA developed the drinking-water standard primarily on the basis of an analysis of the costs of reducing radioactivity in drinking water in relation to the benefits in health risks averted. This approach essentially represents another application of the ALARA objective to standard-setting itself. Although a risk assessment was performed in developing the standards, an a priori judgment about an acceptable risk posed by radionuclides in drinking water was not a consideration in establishing the standards. The dose corresponding to the standard for radium in drinking water can be estimated by assuming that the water contains 226Ra at 0.2 Bq/L (5 pCi/L) and that an individual ingests 2 L of water per day (EPA 1989c). For the effective dose equivalent per unit activity intake of 226Ra given in current federal guidance (Eckerman and others 1988), the estimated effective dose equivalent is about 0.05 mSv (5 mrem) per year. The dose corresponding to the standard for 228Ra in drinking water is nearly the same. In 1991, EPA issued proposed revisions of the interim standards for radioactivity in community drinking-water systems (EPA 1991a). The proposed standards include the following criteria that apply to naturally occurring radionuclides: · A concentration limit of 0.7 Bq/L (20 pCi/L) for 226Ra and Ra separately. · A concentration limit of 20 ~g/L for uranium. . A concentration limit of 11 Bq/L (300 pCi/L) for radon-222. · A concentration limit of 0.6 Bq/L (15 pCi/L) for gross alpha particle activity, excluding 226Ra, uranium, and 222Rn. · A limit on annual effective dose equivalent of 0.04 mSv (4 mrem) for all beta- or gamma-emitting radionuclides, excluding 22aD '~a.

120 GUIDELINES FOR EXPOSURE TO TENORM The proposed standard for uranium was based on prevention of chemical toxicity in the kidney, as well as considerations of cancer risk posed by radiation exposure. On the basis of the observed activity disequilibrium between uranium-238 and its decay product uranium-234 in natural waters and the recognition that the activity of uranium-235 in water is insignificant, the proposed limit on mass concentration for uranium was assumed to correspond to an activity concentration of 1.1 Bq/L (30 pCi/L) (EPA 1991a). The proposed revisions of the drinking-water standards differ from the current standards in the following respects. First, the concentration limit for 226Ra plus 228Ra would be increased by a factor of 8, on the basis of a revised cost-benef~t analysis (EPA 1991a). Second, uranium and 222Rn in drinking water would be regulated for the first time. Third, the standard for gross alpha-particle activity would exclude 226Ra. Finally, the standard for beta- or gamma-em~tting radionuclides, which currently applies only to human-made radionuclides, would also apply to naturally occurring radionuclides other than 228Ra (for example, to lead-210) and would be expressed in terms of the effective dose equivalent rather than the dose to the whole body or any organ. The Safe Drinking Water Act Amendments of 1996 contain two provisions that directly affect the proposed revisions of the drinking-water standards for radionuclides. First, in response to the controversy over the cost- benefit analysis of the proposed standard for radon, the amendments directed that this proposal be withdrawn and that a new standard for radon in drinking water be promulgated by the year 2000 on the basis of results of a study by the National Academy of Sciences; in response to this directive, EPA has withdrawn the proposed standard for radon (EPA 1997~. Second, the amendments specify that any revision of drinking-water standards shall maintain or increase health protection of the public. The proposal to increase the allowable concentrations for radium clearly would result in higher allowable risks. The proposed revision of the standard for beta- or gamma-emitting radionuclides also would result in higher allowable risks because the proposed limit on We effective dose equivalent of 0.04 mSv (4mrem) per year generally results in higher allowable concentrations of radionuclides in drinking water than the same limit on the dose equivalent to any organ or tissue (Eckerman and others 1988~. Therefore, promulgation of the proposed revisions of drinking-water standards for radium and beta- or gamma- emitting radionuclides appears to be precluded by the amendments. Standards for Radioactivity in Liquid Discharges Under authority of the Clean Water Act, EPA develops standards aimed at restoring and maintaining the chemical, physical, and biologic integrity

GUIDANCES AND REGULATIONS FOR NORM 121 of the nation's surface waters. In particular, EPA may establish standards for release of naturally occurring radionuclides into surface waters (see chapter 6~. In 1982, EPA established standards in 40 CFR Part440 for liquid discharges of naturally occurring radionuclides from mines or mills used to produce or process uranium, radium, and vanadium ores (47 FR 54609~. These standards include the following provisions: · Limits on concentrations in effluents for any day of 0.4 Bq/L (10 pCi/L) for dissolved 226Ra, 1.1 Bq/L (30 pCi/L) for total 226Ra, and 4 mg/L for uranium. · Limits on average concentrations in daily effluents for 30 consecutive days of 0.11 Bq/L (3 pCi/L) for dissolved 226Ra, 0.4 Bq/L (10 pCi/L) for total 226Ra, and 2 mg/L for uranium. Those limits were based on considerations of the effectiveness of effluent control technologies, rather than potential health risks to the public posed by ingestion of contaminated surface water. EPA has not developed standards under the Clean Water Act for discharges of naturally occurring radionuclides to surface waters from any other sources. However, as noted in the following section, the standards in 40 CFR Part 440 apply to discharges from active uranium- and thorium-processing sites associated with the nuclear fuel cycle. Standards for Uranium and Thorium Mill Tailings EPA's current standards for uranium and thorium mill tailings in 40 CFR Part 192 were first established in 1983 (48 FR 602 and 48 FR 45946), and the provisions for groundwater protection were revised in 1995 (60 FR 2854~. Those standards are concerned with control and cleanup of residual radioactive materials at or near inactive uranium- and thorium-processing sites and management of uranium and thorium byproduct materials at active processing sites. Only naturally occurring radionuclides are found in mill tailings, and the most important radionuclides of concern in protecting public health are radium, radon, and their decay products. The mill-tailings standards are contained in four Subparts that apply to different aspects of management, disposal, or remediation, as follows. Subpart A For control of residual radioactive materials from inactive uranium-processing sites, that is, uranium mill-tailings piles at inactive processing sites managed by DOE:

122 GUIDELINES FOR EXPOSURE TO TENORM · A limit on annual average release rate to the atmosphere of 0.7 Bq/m2 (20 pCi/m2) per second for 222Rn or a limit on annual average concentration of 20 Bq/m3 (0.5 pCi/L) for 222Rn in air above background outside the disposal site. · Limits on concentrations in groundwater of 0.2 Bq/L (5 pCi/L) for 226Ra plus 228Ra, 0.6 Bq/L (15 pCi/L) for gross alpha-particle activity excluding radon and uranium, and 1.1 Bq/L (30 pCi/L) for 234U plus 238U, with provisions for establishing alternative concentration limits. · Controls for limiting radon emissions and releases to groundwater designed to be effective for up to 1,000 y to the extent reasonably achievable and, in any case, for at least 200 y. Subpart B For cleanup of land and buildings contaminated with residual radioactive materials from inactive uranium-processing sites, that is, for contaminated land and buildings at processing sites managed by DOE and contaminated real property in the vicinity of such sites: . In land averaged over any area of 100 m2, limits on concentrations of 226Ra in soil above background of 0.2 Bq/g (5 pCi/g) averaged over the first 15 cm below the ground surface and 0.6 Bq/g (15 pCi/g) averaged over any 15-cm-thick layers more than 15 cm below the ground surface. · In any occupied or habitable building, a limit on concentration of radon decay products, including background, of 6 x 10-7 J/m3 (0.03 working level (WL)), with an objective for remedial action of 4 x 10- 7 J/m3 (0.02 WL). · In any occupied or habitable building, a limit on gamma radiation level above background of 20 ,uR/h. . Subpart A. Compliance with the groundwater protection standard in Subpart D For management of uranium byproduct materials at active uranium processing sites, that is, for uranium-processing sites licensed by the Nuclear Regulatory Commission or Agreement States (states that enter into licensing agreements with the Nuclear Regulatory Commission):

G UIDANCES AND REG ULA TIONS FOR NORM · During processing operations and before the end of the closure period, compliance with the groundwater-protection standard in Subpart A, except for the concentration limit for 234U plus 238U; the flux standard for 222Rn from tailings piles in Subpart A, but not the concentration standard outside the site; the dose constraint for individual members of the public in 40 CFR Part 190 (see above); and the limits on radioactivity in liquid discharges to surface waters in 40 CFR Part 440 (see above). · After the closure period and for the period specified in Subpart A, compliance with the flux standard for 222Rn from tailings piles in Subpart A, but not the concentration standard outside the site, except that the flux standard does not apply to any portion of a site that contains concentrations of 226Ra in soil above background less than the values specified in Subpart B. 123 Subpart E For management of thorium byproduct materials at active thorium-processing sites, that is, for thorium-processing sites licensed by the Nuclear Regulatory Commission or Agreement States: · Application of the standards for uranium, 222Rn, and 226Ra in Subpart D to thorium, 220Rn, and 228Ra, respectively, except that the flux standard for 222Rn during uranium-processing operations and before the end of the closure period does not apply to releases of 220Rn at thorium-processing sites during the same period. · During thorium-processing operations and before the end of the closure period, limits on annual dose equivalent to individual members of the public of 0.25 mSv (25 mrem) to the whole body, 0.75 mSv (75 mrem) to the thyroid, and 0.25 mSv (25 mrem) to any other organ, excluding the dose from 220Rn and its short-lived decay products. Except for the dose constraint for individual members of the public in Subparts D and E that applies during uranium- or thorium-processing operations and before the end of the closure period, the mill-tailings standards are expressed in terms of quantities that can be measured in the field, rather than dose to individuals. The standards for cleanup of residual radioactive materials in Subpart B. except for the groundwater-protection standards, are interrelated. Specifically, the concentration limit for 226Ra in surface soil of 0.2 Bq/g

124 GUIDELINES FOR EXPOSURE TO TENORM (5 pCi/g) is intended to ensure that the concentration of indoor radon decay products would be less than the objective of 4 x 10-7 J/m3 (0.02 WL) and that the indoor gamma radiation level above background would be less than 20 pR/h (EPA 1982~. However, the concentration limit for 226Ra in subsurface soil of 0.6 Bq/g (lSpCi/g) is not health-based but is intended only to provide a standard that would allow the detection of mill tailings in subsurface soil by direct gamma measurement in the field (EPA 1982~. As discussed in chapter 9, the two cleanup criteria for 226Ra in soil in Subpart B often have been used in standards for TENORM. Most of the provisions in the mill-tailings standards, especially the standards for cleanup of contaminated land and buildings, were based primarily on background levels of radioactivity in areas of the western United States where uranium and thorium ore deposits exist and the residual radioactive materials were obtained (EPA 1982~. In addition, the standards for groundwater protection were based on the interim drinking-water standards in 40 CFR Part 141 with an additional provision for uranium, and the standards for thorium-processing operations and before the end of the closure period were based on the uranium fuel-cycle standards in 40 CFR Part 190. The standard for indoor radon decay products also has been discussed by Harley (1996~. If the activity of the decay products in indoor air is assumed to be 50% of the activity of radon, then the objective for remedial action of 4 x 10-7 J/m3 (0.02 WL) corresponds to a radon concentration of about 150Bq/m3 (4pCi/L), which is the current EPA guideline for mitigation of indoor radon discussed later in this chapter and in chapter 8. As described below, the standards for inactive uranium-mill tailings sites can be converted to estimates of dose to individuals residing on contaminated land near the site. The most important contributors to dose are radium in soil, outdoor and indoor radon, and indoor gamma radiation. An upper bound on the external dose corresponding to the concentration limits for 226Ra in soil can be estimated by assuming continuous external exposure; the presence of all decay products of 226Ra in equilibrium; indoor and outdoor residence times of 85% and 15%, respectively; a dose- reduction factor during indoor residence due to building shielding of 0.7 (Nuclear Regulatory Commission 1977~; and external dose rates per unit concentration of 226Ra in surface soil as given in current federal guidance (Eckerman and Ryman 1993~. On the basis of those assumptions, the estimated annual effective dose equivalent from external exposure is about 0.5 mSv (50 mrem). For mill tailings, the dose from internal exposure to radium and its decay products, except for inhalation of radon decay products (which is considered separately), is expected to be considerably less than the dose from external exposure (EPA 1982~.

GUIDANCES AND REGULATIONS FOR NORM 125 The dose corresponding to the standard for outdoor radon of 20 Bq/m3 (0.5 pCi/L) can be estimated by assuming the mean annual effective dose equivalent per unit concentration for an outdoor residence time of 15% recommended by (ICRP 1987b). On the basis of that assumption, the estimated annual effective dose equivalent is about 0.3 mSv (30 mrem). The dose corresponding to the standard for indoor radon decay products of 6 x 10-7 J/m3 (0.03 WL) can be estimated by assuming the mean annual effective dose equivalent per unit exposure for an indoor residence time of 85% recommended by ICRP (1987b). On the basis of that assumption, the estimated annual effective dose equivalent is about 8 mSv (800 mrem). Finally, the dose corresponding to the standard for indoor gamma radiation can be estimated by assuming that an exposure of 1 R corresponds to an effective dose equivalent of about 7 mSv (700 mrem) (ICRP 1987a) and an indoor residence time of 85%. On the basis of those assumptions, the estimated annual effective dose equivalent is about 1 mSv (100 mrem). That includes the contribution from external exposure to radium in soil. On the basis of those calculations, the mill-tailings standards correspond to a maximum annual effective dose equivalent to individual members of the public of nearly 10 mSv (1,000 mrem), and the contribution from all sources of exposure other than radon is about 1 mSv (100 mrem). The dose from all sources other than radon is less by about a factor of 5 than the primary dose limit of 5 mSv (500 mrem) per year from all controlled sources combined in the existing FRC guidance on radiation protection of the public (FRC 1960) but is essentially the same as the primary dose limit of 1 mSv (100 mrem) from all controlled sources combined in EPA's proposed revision of the federal guidance (EPA 1994d). Therefore, compliance with the recommendation in the proposed revision of the federal guidance that the dose from individual sources or practices normally should be limited to a fraction of the dose limit of 1 mSv (100 mrem) per year appears to be impractical for properties in the vicinity of uranium mill tailings disposal sites. The dose calculations described above apply only to individuals residing on contaminated properties near uranium mill tailings sites, but they do not apply to individuals who might reside on a tailings pile itself at some time in the future. Given that undiluted mill tailings typically contain 226Ra at about 10- 40 Bq/g (300-1,000 pCi/g) (DOE 1996), in contrast with the cleanup standard for 226Ra in surface soil of 0.2 Bq/g (5 pCi/g), permanent residence on an exposed tailings pile (for example, a pile whose cover had been removed inadvertently) would result in doses from external exposure and exposure to indoor radon that are about 2 orders of magnitude higher than the dose estimates for residence on contaminated land near the site. Such high doses clearly would be unacceptable under any circumstances. However, the intent under the Uranium Mill Tailings Radiation Control Act is that the high doses that could

126 GUIDELINES FOR EXPOSURE TO TENORM result from residence on a mill-tailings pile would be prevented by maintaining perpetual federal control over the sites to preclude permanent occupancy by members of the public. Standards for Management and Disposal of Radioactive Waste Under authority of the Atomic Energy Act, EPA has established standards for management and disposal of spent nuclear fuel, high-level waste, and transuranic waste. EPA also is developing standards for low-level waste. Standards for Spent Fuel, High-Level Waste, and Transuranic Waste EPA's current standards for spent nuclear fuel, high-level waste, and transuranic waste in 40 CFR Part 191 were first established in 1985 (50 FR 38066) and then revised in 1993 (58 FR 66398~. The standards apply to management (except for transportation), storage, and disposal of waste, and they apply to naturally occurring radionuclides in the wastes. The standards for management and storage of spent fuel, high-level waste, and transuranic waste include the following provisions: · For facilities regulated by the Nuclear Regulatory Commission or Agreement States, and including all operations of uranium fuel- cycle facilities covered by 40 CFR Part 190, limits on annual dose equivalent to individuals of 0.25 mSv (25 mrem) to the whole body, 0.75 mSv (75 mrem) to the thyroid, and 0.25 mSv (25 mrem) to any other organ. · For facilities operated by DOE and not regulated by the Nuclear Regulatory Commission or Agreement States, limits on annual dose equivalent to individuals of 0.25 mSv (25 mrem) to the whole body and 0.75 mSv (75 mrem) to any organ or, on application for an alternative standard, limits on annual dose equivalent from all sources combined, excluding natural background and medical practices, of 1 mSv (100 mrem) for continuous exposure or 5 mSv (500 mrem) for infrequent exposure. Those standards are intended to be consistent with the uranium fuel- cycle standards in 40 CFR Part 190 discussed above. Because the fuel-cycle standards were based primarily on judgments about doses that were reasonably achievable with available effluent-control technologies, rather than doses that must be achieved to protect public health, the difference between the standards for waste management and storage for facilities regulated by the Nuclear Regulatory Commission or Agreement States and the standards for DOE facilities not regulated by the Nuclear Regulatory Commission or Agreement

GUIDANCES AND REGULA TIONS FOR NORM 127 States is a clear example of establishing standards based on doses judged by EPA to be reasonably achievable. The standards for disposal of spent fuel, high-level waste, and transuranic waste include the following provisions: · For 10,000 years after disposal, cumulative releases of radionuclides to the accessible environment, taking into account inadvertent human intrusion (such as drilling) and undisturbed performance of the disposal system, shall have a likelihood of less than one chance in 10 of exceeding specified values and less than one chance in 1,000 of exceeding 10 times the specified values. · For 10,000 years after disposal, undisturbed performance of the disposal system shall not cause the annual effective dose equivalent to individuals in the accessible environment from all potential exposure pathways to exceed 0.15 mSv (15 mrem). · For 10,000 years after disposal, undisturbed performance of the disposal system shall not cause radioactivity in any underground source of drinking water in the accessible environment to exceed limits (that is, the MCLs) specified in 40 CFR Part 141 as they existed when the disposal standards became effective. In the first of those provisions, referred to as the containment requirements, the limits on cumulative releases of radionuclides to the accessible environment were developed on the basis of judgments about releases that are reasonably achievable with foreseeable technology for disposal in geologic repositories. Thus, the containment requirements were based on an application of the ALARA objective. The release limits correspond to about 1,000 deaths in the US population over 10,000 y (an average of one every 10 y). Naturally occurring radionuclides are important constituents of spent fuel and high-level waste but are unimportant in transuranic waste. For disposal of spent fuel and high-level waste, the containment requirements are expressed in terms of limits on cumulative releases of radionuclides per 1,000 metric tons of heavy metal (MTHM) irradiated in a reactor. For naturally occurring radionuclides, the specified release limits per 1,000 MTHM are 3.7 TBq (100 Ci) for 226Ra 234U 235U and MU; O 37 TBq (10 Ci) for thorium 230 and thorium-232; and 37 TBq (1,000 Ci) for Pub. Because the containment requirements apply only for 10,000 y, during which time the buildup of radium in chemically separated uranium would be relatively unimportant, and because thorium has been used only infrequently in nuclear fuel, the containment

128 GUIDELINES FOR EXPOSURE TO TENORM requirements should be more important for uranium than for other naturally occurring radionuclides. In the second disposal requirement described above, the constraint on annual effective dose equivalent of 0.15 mSv (15 mrem) for individuals was based on three considerations. First, EPA judged that this dose corresponds to a limit on lifetime cancer risk that is consistent with the constraint on annual dose equivalents~.25 mSv (25 mrem) to the whole body and 0.75 mSv (75 mrem) to any organ-in the original individual-protection requirement promulgated in 1985 (50 FR 38066~. Second, EPA judged that this dose would provide an acceptable level of risk for the few individuals likely to be living near the small number of disposal sites. Third, EPA's analyses of the undisturbed performance of disposal systems (absent human intrusion) indicated that the specified dose constraint should be reasonably achievable at well-chosen sites. The third disposal requirement described above addresses protection of groundwater near disposal sites. The essence of this requirement is that waste disposal should not cause any potential drinking-water supply to exceed standards (MCLs) developed under the Safe Drinking Water Act. This requirement reflects EPA's general policy that the nation's groundwater resources should be protected to avoid future costs of water treatment (EPA l991b). In this regard, it is important to recall that drinking-water standards for radionuclides are based primarily on judgments about levels of radioactivity that are reasonably achievable given existing background and available technology for water treatment, rather than a judgment about risks to public health that must be achieved without regard for the costs of water treatment. Therefore, the groundwater-protection requirement for waste disposal clearly is not based solely on a judgment about acceptable risk posed by radionuclides in drinking water. EPA's analyses for undisturbed performance of waste-disposal systems also indicated that the groundwater-protection requirement should be reasonably achievable at well-chosen sites. The containment requirements (cumulative release limits) in the disposal standards generated considerable controversy when they were promulgated in 1985, in part because they were based on estimated impacts on the entire US population but would not necessarily provide adequate protection of individuals near disposal sites. The individual-protection requirement promulgated in 1993 was intended to address that concern. However, the period of 10,000 y for applying the containment requirements also was controversial, given the much longer time over which spent fuel and high-level waste would remain hazardous. In the Energy Policy Act of 1992, Congress responded to both controversies by directing EPA to issue new standards, to be based on results of a study by the National Academy of Sciences, that would apply only to disposal of spent fuel and high-level waste at the Yucca Mountain site in Nevada, which is the only authorized disposal facility for such waste.

GUIDANCES~1ND REGULATIONS FOR NORM 129 Furthermore, Congress indicated a preference for an individual-dose standard, rather than the existing containment requirements, for the Yucca Mountain site. The congressional directive essentially discarded the existing disposal standards for this site, especially the containment requirements. The Academy report on Yucca Mountain standards was completed in 1995 (National Research Council 1995~. The report recommended that the limits on cumulative releases of radionuclides to the accessible environment over 10,000 y be replaced with a standard for individual risk (not dose) that would be applied for a period consistent with the expected geologic stability of the Yucca Mountain site (perhaps on the order of 106 y). EPA has not issued proposed new disposal standards for the Yucca Mountain site in response to the congressional directive. The only authorized facility to which the current disposal standards promulgated in 1993 apply is the Waste Isolation Pilot Plant (WIPP) in New Mexico for disposal of DOE's transuranic waste. Standards for Low-Level Waste EPA has not issued proposed standards for management and disposal of low-level radioactive waste. In a draft proposed rule (EPA 1994a), EPA indicated a preference for a standard for management and storage in the form of a constraint on annual effective dose equivalent for individuals of 0.15 mSv (15 mrem) from all exposure pathways and a standard for disposal in the form of the same constraint on individual dose plus a separate requirement for groundwater protection that would be consistent with MCLs for radioactivity in drinking water established in 40 CFR Part 141 under the Safe Drinking Water Act. The preferred disposal standard thus would be consistent with the individual-protection and groundwater-protection requirements in the standards for disposal of spent fuel, high-level waste, and transuranic waste in 40 CFR Part 191. EPA also indicated a preference that the disposal standard for low-level waste apply for 1,000 y. Standards for Cleanup of Radioactively Contaminated Sites In addition to the standards for remediation of contaminated land and buildings at or near inactive uranium and thorium mill tailings sites, EPA develops standards for cleanup of other radioactively contaminated sites, including sites where deliberate disposal of radioactive waste occurred in the past. Any such standards apply to cleanup of naturally occurring radionuclides that were released to the environment or enhanced in the environment by human activities. Current Cleanup Standards for Radionuclides Remediation of radioactively contaminated sites is regulated by EPA mainly under authority of CERCLA and its implementing regulations in the National Contingency Plan (NCP) in 40 CFR Part 300, which was promulgated in 1990 (55 FR 8666~.

130 GUIDELINES FOR EXPOSURE TO TENORM CERCLA addresses environmental contamination that is not properly regulated under other laws (such as the Atomic Energy Act, the Clean Air Act, the Safe Drinking Water Act, the Clean Water Act, and RCRA). An essential feature of CERCLA and the NCP is that they do not specify a priori requirements for remediation of contaminated sites. That is, CERCLA and the NCP do not specify risks, doses, or levels of hazardous substances in the environment above which remedial actions are required regardless of cost or other circumstances. Rather, CERCLA and the NCP specify preliminary remediation goals, which normally are based on standards promulgated under other environmental laws. When the preliminary remediation goals are exceeded at a site, the feasibility of reducing risk must be investigated, but, as described later in this section, actions to reduce risk are not necessarily required. With the goals as a starting point, the cleanup levels actually achieved, as incorporated in the record of decision (ROD), are developed by a complex process of risk assessment, evaluation of the costs and benefits of alternatives for remediation, and negotiation among all stakeholders in the decision. CERCLA and the NCP specify that the preliminary remediation goals at any site shall be protective of human health and the environment, and shall take into account: · Applicable or relevant and appropriate requirements (ARARs) established under other federal or state environmental laws, with federal drinking-water standards established in 40 CFR Part 141 under authority of the Safe Drinking Water Act specified as ARARs for cleanup of contaminated groundwater and surface water. · Other information to be considered (TBCs) that is not an ARAR, such as EPA's groundwater-protection strategy (EPA l991b) and DOE Orders. · For known or suspected carcinogens (such as radionuclides), an upper bound on lifetime cancer risk of 10-4 to 10-6 posed by all substances and all exposure pathways combined. Several points about the preliminary remediation goals should be noted. First, for radionuclides, the drinking-water standards specified as ARARs for remediation of contaminated groundwater and surface water are the MCLs described earlier in this chapter, and the goals apply only to sources that are current or potential sources of drinking water. Second, TBCs generally are less important than ARARs and the cancer-risk criterion in developing remediation goals, because they have not been subjected to a public rule-making process. Finally, the goal for lifetime cancer risk was based on the levels of risk

GUIDANCES AND REGULATIONS FOR NORM 131 embodied in regulations established under other laws, including the Safe Drinking Water Act and the Clean Air Act. However, later EPA directives for carcinogens in general (Clay 1991) and radionuclides in particular (Luftig and Weinstock 1997) have indicated that lifetime cancer risks less than about 10-4 normally would not need to be considered in establishing preliminary remediation goals, that is, the cancer-risk goal of 10-4 to 10-6 specified in the NCP normally should be interpreted as a single value of 10~. Thus, cancer risks less than about 10-4 usually would be considered negligible because investigations into the feasibility of reducing risks beyond these low levels normally would not be required. The preliminary remediation goals described above define desired levels of environmental contamination to be achieved in site cleanups under CERCLA. However, the goals are not unqualified requirements; CERCLA and the NCP also specify several conditions for waiving compliance with the ARARs, TBCs, or the cancer-risk goal in establishing actual cleanup levels at any site. Compliance with the preliminary remediation goals can be waived, for example, if the remedial action is an interim measure, if compliance would result in a greater risk to public health and the environment than noncompliance, if compliance is technically infeasible or impractical, if another response would achieve an equivalent level of protection, or if compliance would not balance the cost of the response against the benefit in protecting public health and the environment. In essence, compliance with the preliminary remediation goals is required only when it is practicable and cost-effective. Negotiated cleanup levels at different sites, as incorporated in RODs, have varied considerably and usually have corresponded to lifetime cancer risks of about 10-4-10-2, that is, substantially above the goal of 10 ~ (EPA 1994b; Baes and Marland 1989~. Thus, lifetime risks above the goal of 10 ~ clearly are not "unacceptable," because risks above the goal have been accepted by EPA and other stakeholders in most cleanup decisions. The most important factors in past cleanup decisions have been cost and feasibility, rather than compliance with ARARs, TBCs, or the cancer-risk goal. The process of arriving at negotiated cleanup levels at any CERCLA site thus clearly resembles applications of the ALARA objective to control of radiation exposures under authority of the Atomic Energy Act. A few contaminated sites are being remediated under authority of RCRA rather than CERCLA. Although the definition of hazardous waste in RCRA specifically excludes radioactive materials as defined in the Atomic Energy Act (source, special nuclear, and byproduct materials), this exclusion does not apply to other radioactive materials, including naturally occurring radioactive materials, not associated with the nuclear fuel cycle. Of particular importance to site cleanups under RCRA are the provisions of EPA's implementing regulations in 40 CFR Part 264 that apply standards similar to the

132 GUIDELINES FOR EXPOSURE TO TENORM MCLs for drinking water in 40 CFR Part 141 to protection of groundwater and require corrective actions if the groundwater-protection standards are exceeded. Future Cleanup Standards for Radionuclides EPA intends to develop standards for cleanup of radioactively contaminated sites under authority of the Atomic Energy Act. These standards could be applied to licensees of the Nuclear Regulatory Commission or Agreement States, sites under control of a federal agency (such as DOE), and any sites subject to remediation under CERCLA that do not have signed RODs; but the standards probably will not be applied to facilities for disposal of spent fuel, high-level waste, or transuranic waste regulated under 40 CFR Part 191, uranium mill tailings sites that comply with 40 CFR Part 192, or sites that have been remediated under CERCLA with signed RODs. In contrast with the current approach to remediation of contaminated sites under CERCLA of first establishing preliminary remediation goals and then negotiating acceptable cleanup levels at specific sites that might be above the goals when compliance with the goals is not feasible the cleanup standards for radionuclides that EPA intends to develop under the Atomic Energy Act would establish requirements that must be met to permit unrestricted or restricted release of contaminated sites. An important challenge for the new standards will be to reconcile Me different concepts of risk goals under CERCLA and dose (risk) limits under the Atomic Energy Act and to show that the standards would be reasonably achievable at most sites. EPA has not issued proposed standards for cleanup of radioactively contaminated sites, although it has performed technical analyses to address the costs and benefits of different cleanup levels (Wolbarst and others 1996~. In a draft proposed rule (EPA 1994b) and a later directive (Lultig and Weinstock 1997), EPA has indicated a preference that a site could be released for unrestricted use if the annual effective dose equivalent to individuals, assuming a residential land-use scenario, would not exceed 0.15 mSv (15 mrem), which corresponds to a lifetime cancer risk of about 10-4; if levels of radon in existing and future structures would comply with the guidance on indoor radon discussed later in this chapter; and if levels of radioactivity in groundwater that is a current or potential source of drinking water would comply with drinking- water standards (MCLs) in 40 CFR Part 141, unless compliance is technically impractical. Thus, the preferred standards for cleanup of radioactively contaminated sites would be consistent with existing standards for disposal of spent fuel, high-level waste, and transuranic waste in 40 CFR Part 191 and draft proposed standards for disposal of low-level waste discussed above. EPA also indicated that the cleanup standards for radionuclides should apply for 1,000 y.

G UIDANCES AND REG ULA TIONS FOR NOW Standards for Airborne Emissions of Radionuclides 133 Under authority of the Clean Air Act, EPA has established National Emission Standards for Hazardous Air Pollutants (NESHAPs) in 40 CFR Part 61. The current NESHAPs for radionuclides were first established in 1989 (54 FR 51654) and then amended in 1991 (56 FR 65934), 1992 (57 FR 23305), 1994 (59 FR 36280), 1995 (60 FR 46206), and 1996 (61 FR 68972~. The current standards include the following provisions that apply to naturally occurring radionuclides: · A limit on annual effective dose equivalent to individuals of 0.1mSv (lOmrem) for DOE facilities emitting any radionuclide other than radon, except for disposal facilities subject to 40 CFR Part 191 or 40 CFR Part 192 and excluding the dose from 222Rn and its decay products; non-DOE federal facilities, except for disposal facilities subject to 40 CFR Part 191, inactive uranium mill tailings disposal sites subject to 40 CFR Part 192, and low-energy accelerators, and excluding the dose from 222Rn; and emissions of 222Rn from specified underground uranium mines. · A limit on emissions of polonium-210 from all calciners and nodulizing kilns at elemental-phosphorus plants of 0.07 TBq (2 Ci) per year or a limit on total emissions from any plant of 0.17 TBq (4.5 Ci) per year when specified scrubbers are installed. · A limit on average concentration of 226Ra of 0.4 Bq/g (10 pCi/g) in phosphogypsum distributed in commerce for uses in agriculture. · A limit on emission rate of 222Rn of 0.7 Bq/m2 (20 pCi/m2) per second from DOE facilities for storage and disposal of material containing radium, inactive phosphogypsum stacks (waste piles from phosphate mining), and operating and inactive uranium mill tailings piles, except for inactive disposal sites licensed by the Nuclear Regulatory Commission. The standards issued in 1989 also applied to specified licensees of the Nuclear Regulatory Commission and Agreement States, including inactive uranium mill tailings disposal sites, nuclear power reactors, and facilities other than nuclear power reactors except for users of radionuclides only in the form of sealed sources. However, EPA has rescinded ~e standards for licensed commercial facilities on the basis of the 1990 Clean Air Act Amendments and a memorandum of understanding with the Nuclear Regulatory Commission. In

134 GUIDELINES FOR EXPOSURE TO TENORM effect, EPA has agreed that Nuclear Regulatory Commission regulations in 10 CFR Part SO, AppendixI, and 10 CFR Part20 limit airborne emissions of radionuclides to an extent consistent with or more restrictive than EPA standards. In establishing NESHAPs for radionuclides, EPA followed a previous mandate by the court of appeals regarding the standard for vinyl chloride (for example, EPA 1989d). The court directed EPA to use a two-step decision process in setting NESHAPs. Specifically, EPA was to determine a "safe" or "acceptable" risk to individuals or populations and an "ample margin of safety" below the safe or acceptable risk for protection of public health. The court ruled that technical feasibility and cost could not be the primary basis for the standards, as has often been the case with EPA standards developed under other laws, including the Atomic Energy Act, the Safe Drinking Water Act, and the Clean Water Act. In response to the court order, EPA set NESHAPs for radionuclides (and other carcinogens) such that the lifetime risk to individuals would not exceed about 10= and the lifetime risk to the greatest number of individuals in exposed populations (that is, the average individual risk) would not exceed about 10-6 (EPA 1989d). The limits on risk used in establishing the NESHAPs were developed on the basis of a survey of other societal risks, and the assumed acceptable risks were consistent with other regulatory precedents, such as standards (MCLs) for radionuclides and other carcinogens in drinking water in 40CFRPartl41. Several additional points about the approach to setting NESHAPs, which applied before the 1990 Clean Air Act Amendments, should be noted. First, radionuclides and other carcinogens were regulated individually. Although the NESHAPs for any carcinogens were based primarily on considerations of acceptable risk, there was no standard defining a limit on acceptable risk posed by exposure to airborne emissions of all carcinogens combined. Second, EPA did not establish NESHAPs for some sources of airborne emissions of naturally occulting radionuclides, including surface uranium mines and coal-f~red boilers. In both cases, the estimated risks to maximally exposed and average individuals were less than the assumed acceptable levels of 10-4 and 10-6, respectively, although the estimated average risk posed by coal-fired boilers was higher than the average risk associated with DOE facilities or nuclear power plants (EPA 1989d). In addition, releases of radionuclides for those two source categories are effectively controlled under other laws and regulations (EPA 1989d). Third, in establishing the standards for radionuclides, especially the authorized limit on annual effective dose equivalent of 0.1 mSv (10 mrem) for many sources, EPA ignored a statement by NCRP (1984a) that a limit on annual effective dose equivalent of 1 mSv (lOOmrem) from all controlled sources

G UIDANCES AND REG ULA TIONS FOR NORM 135 combined provides an upper bound on acceptable risk to individuals and that an authorized limit for specific sources or practices at 25% of the dose limit for all sources and further application of the ALARA objective at specific sites would provide an adequate margin of safety for exposed individuals and populations. Fourth, EPA envisioned that the two-step decision process based on considerations of acceptable risk, as mandated by the court of appeals in the vinyl chloride case, would be applied only in establishing NESHAPs under the Clean Air Act but would not be applied to any other regulations developed under the act or to regulations developed by EPA under any other laws (such as the Atomic Energy Act and the Safe Drinking Water Act). Finally, although the court of appeals mandated considerations of acceptable risk, the resulting standards were shown to be reasonably achievable with existing effluent-control technologies (EPA 1989d). EPA (1989d; 1989b) also noted that the feasibility of emission controls was considered in determining an ample margin of safety, which is the second part of the two-step decision process described above and was used in establishing the limit on average individual risk of about 10-6. In the Clean Air Act Amendments of 1990, the risk-based approach to setting NESHAPs was replaced with an approach based primarily on maximum achievable control technology. However, all NESHAPs established before the Amendments Act, including the standards for radionuclides described in this section, remain in effect. Guidance on Radon in Homes In 1986, EPA and the Department of Health and Human Services issued guidance on radon in homes (EPA and DHHS 1986), which poses the greatest radiation risk to the public (see table 2.10~. The guidance included the statement that mitigation of exposures was indicated for radon concentrations above 150Bq/m3 (4pCi/L), which corresponds to an exposure to short-lived radon decay products of about 4x 10~7J/m3 (0.02 WL). The recommended mitigation level was based on considerations of risks to individuals, an analysis of existing levels of radon in homes, and the costs and benefits of reducing these levels. The guidance was not a standard for limiting exposures of the public to radon in homes, but it has been widely used in the real-estate and home- insurance industries. The Indoor Radon Abatement Act of 1988 established the goal of reducing indoor radon concentrations to background (outdoor) levels, which average about 7 Bq/m3 (0.2 pCi/L) but are highly variable (NCRP 1987a). In response to the act, the guidance on indoor radon was reevaluated (EPA and DHHS 1994~. The guidance continues to state, on the basis of further cost- benefit analysis, that radon concentrations in homes above 150 Bq/m3 (4 pCi/L)

136 GUIDELINES FOR EXPOSURE TO TENORM indicate a need for mitigation of exposures. However, the current guidance also recommends that mitigation of exposures be considered for concentrations of 70-150 Bq/m3 (2-4 pCi/L), especially if the concentrations can be reduced below 70 Bq/m3 (2 pCi/L). For exposure at the recommended mitigation level of 150 Bq/m3 (4 pCi/L), the estimated lifetime risk of fatal lung cancers is 2 x 10-3 for people who have never smoked and 3 x 10-2 for smokers (EPA and DHHS 1994~. For former smokers, the risk might lie between Hose two values. EPA guidance on indoor radon is considered in more detail in chapter 8. Applicability of EPA Guidances and Regulations to TENORM Up to now, this chapter has discussed EPA's published guidances and regulations, either existing or proposed, that apply to naturally occurring radionuclides without regard for whether the standards apply to TENORM, as defined in this study, or to naturally occurring radionuclides associated with operations of the nuclear fuel cycle, which are not included in TENORM. The following statements summarize the applicability of the various guidances and regulations to TENORM, except the guidance for indoor radon, which clearly is concerned only with a particular type of TENORM. · Existing federal guidance on radiation protection of the public and EPA's proposed revision of the federal guidance are intended to apply to all sources of exposure to TENORM, except indoor radon. · Standards for operations of uranium fuel-cycle facilities in 40 CFR Part 190 do not apply to TENORM, because they apply only to radioactive materials regulated under the Atomic Energy Act. · Standards for radioactivity in drinking water in 40 CFR Part 141 apply to TENORM from any source (and also include natural background). · Standards for liquid discharges from mines or mills used to produce or process uranium, radium, and vanadium ores in 40 CFR Part 440 apply to TENORM from the specified sources. · Standards for uranium and thorium mill tailings in 40 CFR Part 192 do not apply to TENORM, because they apply only to radioactive materials regulated under the Atomic Energy Act. However, because mill tailings contain only naturally occurring

G UIDANCES AND REG ULA TIONS FOR NORM radionuclides, the standards have been widely used as a model for regulating TENORM (see chapter 9~. · Standards for management and disposal of spent fuel, high-level waste, and transuranic waste in 40 CFR Part 191 and standards for management and disposal of low-level waste that might be developed do not apply to TENORM, because they apply only to radioactive materials regulated under the Atomic Energy Act. · Standards for cleanup of radioactively contaminated CERCLA sites in 40 CFR Part 300 apply to TENORM. · Standards for airborne emissions of radionuclides in 40 CFR Part 61 apply to TENORM from the specified sources. 137 In chapter 10, EPA guidances and regulations that apply to TENORM are summarized and compared with guidances for TENORM developed by other organizations. Other EPA Initiatives for TENORM In addition to the guidances and regulations for TENORM discussed previously in this chapter, EPA has undertaken other initiatives for TENORM. These include the development of guidelines for disposal of wastes arising from treatment of drinking water and for the use and disposal of sewage sludge. Guidelines for Drinking-Water Treatment Wastes EPA has developed suggested guidelines for disposal of drinking-water treatment wastes that contain naturally occurring radionuclides (EPA 1994e). The current guidelines supersede those issued previously (EPA 1990~. The guidelines are intended only to provide assistance to drinking-water treatment facilities where gaps in existing state regulations for disposal of wastes containing naturally occurring radionuclides exist, but they do not establish or affect any legal rights or obligations. Separate guidelines were developed for disposal of liquid and solid wastes. The guidelines for disposal of liquid wastes from treatment of drinking water consider disposal into storm sewers, surface waters, sanitary sewers, and wells. These guidelines are summarized as follows. For disposal into storm sewers and surface waters, requirements for obtaining National Pollutant Discharge Elimination System (NPDES) permits established under the Clean Water Act generally apply. That is, releases of liquid wastes from treatment of drinking water that contains naturally occurring

138 GUIDELINES FOR EXPOSURE TO TENORM radionuclides are subject to limits specified in NPDES permits, and no additional guidance is needed. For disposal into sanitary sewers, the suggested guidelines include the following: · The daily quantities of soluble 226Ra and 228Ra, diluted by the average daily quantity of water-treatment wastes released into the sewer, should not exceed 15 Bq/L (400 pCi/L) and 30 Bq/L (800 pCi/L), respectively. · The daily quantity of soluble natural uranium, diluted by the average daily quantity of water-treatment wastes released into the sewer, should not exceed 37 kl3q/L (1 pCi/L). · The gross quantity of radioactive material released by a facility into the sanitary sewer should not exceed 37 GBq (1 Ci) per year. Those guidelines were based on standards for Nuclear Regulatory Commission and Agreement State licensees that had been established in 10 CFR Part 20. The guidelines for subsurface disposal in wells were based on regulations for the Underground Injection Control (UIC) program established under the Safe Drinking Water Act. The UIC program distinguishes between radioactive and nonradioactive wastes on the basis of radionuclide concentrations, and the concentration limits for nonradioactive waste for the naturally occurring radionuclides of concern are 1.1 Bq/L (30 pCi/L) for 226Ra and 228Ra and 1.1 kBq/L (30,000 pCi/L) for natural uranium. The suggested guidelines include the following: · Shallow injection of radioactive waste that is, injection above or into an underground source of drinking water (USDW:is banned under the UIC program. . Deep-well disposal of radioactive waste below a USDW or shallow injection of nonradioactive waste is considered a Class V well, but no recommendations are made regarding disposal of drinking-water treatment wastes that contain naturally occurring radionuclides in Class V wells. · Nonradioactive waste should be disposed of in a Class I well beneath the lowest USDW.

G UIDANCES AND REG ULA TIONS FOR NORM 139 If there are no acceptable methods for disposal of liquid wastes, then the wastes normally should be solidified for disposal in accordance with the guidelines for solid waste arising from water treatment. The guidelines for disposal of solid drinking-water treatment wastes that contain naturally occurring radionuclides also depend on the concentrations of radionuclides. The guidelines are as follows. · Solid wastes that contain 226Ra plus 228Ra at less than 0.1 1 Bq/g (3 pCi/g) and uranium at less than 50 Agog may be disposed of, without the need for long-te~m institutional controls, in a municipal landfill, provided that the radioactive wastes are mixed with other materials when emplaced and that the radioactive wastes constitute less than about 10% of the volume of material in the landfill. · Solid wastes that contain 226Ra plus 228Ra at 0.11-1.9 Bq/g (3- 50 pCi/g) should be disposed of with a cover that would protect against radon release and would isolate the wastes, and institutional controls designed to avoid inappropriate uses of the disposal site should be provided. Sites that comply with disposal requirements for nonhazardous waste developed under Subtitle D of RCRA would be adequate. . For solid wastes that contain 226Ra plus 228Ra at 1.9-74 Bq/g (50-2,000 pCi/g), the disposal method should be determined case-by- case. The disposal options considered should include methods that comply with standards for disposal of uranium mill tailings or with standards for disposal of hazardous waste developed under Subtitle C of RCRA, a facility licensed by a state for waste that contains naturally occurring and accelerator-produced radioactive material (NARM), and for concentrations approaching 74 Bq/g (2,000 pCi/g) a facility for low-level radioactive waste licensed by the Nuclear Regulatory Commission or an Agreement State under the Atomic Energy Act or a facility permitted by EPA or a state to dispose of discrete NARM. . For solid wastes that contain uranium at 50-500 ,ug/g, the disposal method should be determined case-by-case. Disposal at sites licensed by states for NARM waste or other radioactive wastes and recovery of the uranium when the wastes contain uranium at more than 0.05% by weight should be considered.

140 GUIDELINES FOR EXPOSURE TO TENORM · Wastes that contain radium at more than 74 Bq/g (2,000 pCi/g) or uranium at more than 500 Agog should be disposed of only as permitted by regulations. · For wastes containing 2'0Pb, the disposal practice should be based on case-by-case reviews. lithe concentration limits of 0.11 Bq/g (3 pCi/g) for 226Ra plus 228Ra and 50 Gag for uranium for disposal in municipal landfills without the need for physical barriers or long-term institutional controls were based on the principle that the relatively high average risks posed by exposure to background radium and uranium in soil should not be allowed to increase by more than a small amount. EPA's suggested guidelines for disposal of radioactive waste arising from treatment of drinking water are not considered further in this report. Radioactivity in Sewage Sludge In 1993, EPA established standards in 40 CFR Part S03 for the use or disposal of sewage sludge (58 FR 9248), including standards for selected heavy metals and pathogens. However, standards for radioactivity are not included. During this study, the committee was informed of current work by the Interagency Steering Committee on Radiation Standards to investigate levels of radioactivity in sewage sludge and the need for appropriate guidance. Its Subcommittee on Sewage Sludge and Ash is conducting a survey of municipal sewage treatment plants to determine levels of TENORM and NRC licensee discharged radionuclides found in sludge and ash. Other Alternatives for EPA Regulation of TENORM As noted earlier, EPA also may regulate NARM and therefore TENORM, which are not subject to regulation under the Atomic Energy Act, under TSCA and RCRA. Although EPA has not developed any such regulations, this section briefly considers the possible regulation of TENORM under TSCA and RCRA. Regulation of TENORM under the Toxic Substances Control Act TSCA is concerned with protection of human health and the environment in the use of toxic substances in commerce. Source, special nuclear, and byproduct materials regulated under Me Atomic Energy Act are excluded from regulation under TSCA, but the exclusion does not apply to NARM. Therefore, EPA may establish standards for management and disposal of TENORM under TSCA if the unregulated use and disposal of these materials presents an unreasonable risk of injury to heal or the environment (Cameron 1996; EPA 1989a). In 1989, EPA prepared an unpublished draft standard for NARM under TSCA (EPA 1989a). It applied only to the relatively small volumes of material

GUIDANCES AND REGULATIONS FOR NORM 141 that contains radioactivity at more than 74 Bq/g (2 nCi/g), that is, to so-called discrete sources. EPA indicated its intention that discrete NARM and TENORM should be regulated as though they were low-level radioactive waste, which is regulated under the Atomic Energy Act. The draft standard did not indicate how EPA intended to regulate the much larger volumes of TENORM that contain lower concentrations of radionuclides, that is, the so-called diffuse sources. Regulation of TENORM under the Resource Conservation and Recovery Act RCRA is concerned, in part, with management and disposal of hazardous and nonhazardous solid waste. As in the case of TSCA, radioactive materials regulated under the Atomic Energy Act are excluded from regulation under RCRA, but the exclusion does not apply to NARM. Thus, EPA may establish standards for management and disposal of waste that contains TENORM under RCRA. An important distinction between regulation of TENORM under TSCA and under RCRA is that RCRA applies only to waste materials, whereas TSCA applies to uses of materials, as well as wastes. As described below, TENORM could be regulated under RCRA in two ways. First, waste that contains TENORM could be regulated under Subtitle C of RCRA, which addresses management and disposal of solid hazardous waste. However, the definition of hazardous waste in EPA regulations that implement Subtitle C of RCRA does not include NARM or, therefore, TENORM, and EPA cannot regulate TENORM as hazardous waste unless it is so declared in regulations that implement RCRA (40 CFR Part 261~. Furthermore, some potentially important wastes that contain TENORM are specifically excluded from the current definition of hazardous waste in 40 CFR Part 261, including mining overburden that is returned to the mine site; some wastes generated from the combustion of coal or other fossil fuels; wastes associated with the exploration, development, or production of crude oil, natural gas, or geothermal energy; and solid waste from the extraction, beneficiation, and processing of some ores and minerals, including coal, phosphate rock, and overburden from the mining of uranium ore. Therefore, for EPA to regulate waste that contains TENORM under Subtitle C of RCRA, substantial changes in the current regulatory definition of solid hazardous waste would be required. As an alternative, waste that contains TENORM could be regulated under Subtitle D of RCRA, which is concerned with disposal of nonhazardous waste in municipal (sanitary) landfills. This approach has the advantage that changes in the regulatory definition of hazardous waste to include TENORM would not be required. However, it would be appropriate only if disposal of waste that contains TENORM in the same manner as ordinary household trash would provide adequate protection of public health and the environment. Therefore, disposal of waste that contains TENORM as nonhazardous waste under RCRA presumably would be suitable only for materials that contain

142 GUIDELINES FOR EXPOSURE TO TENORM relatively low concentrations of radionuclides that would pose no more than negligible risks to public health and the environment. Risks Corresponding to EPA Guidances and Regulations An additional perspective on EPA's guidances and regulations for naturally occurring radionuclides discussed above and summarized in table 7.1 is provided by the data in table7.2, where quantitative criteria in various guidances and regulations are expressed in terms of the corresponding lifetime risk of fatal cancers, assuming continuous exposure over 70 y. Table 7.2 also includes the lifetime risks resulting from exposure to natural background radiation, including indoor radon, and to indoor radon only. In converting effective dose equivalents to risk, the risk per unit dose is assumed to be 5 x 10-s per millisievert (5 x 10-7 per millirem) (EPA 1994c; NCRP 1993a; ICRP 1991), and the risk corresponding to a specified dose to a particular organ takes into account the relationship between organ dose equivalent and effective dose equivalent for the particular radionuclide of concern, as obtained from current federal guidance (Eckerman and others 1988~. The data in table 7.2 indicate that the risks corresponding to the various guidances and regulations that apply to naturally occurring radionuclides vary considerably and that many of the risks corresponding to current standards are considerably smaller than the risks posed by natural background radiation. However, as discussed in the following section, there are many valid reasons why the various guidances and regulations are not consistent with regard to the corresponding levels of risk. CONSISTENCY OF DIFFERENT GUIDANCES AND REGULATIONS As the number of environmental laws and regulations has increased in recent years, there has been considerable interest in the issue of the consistency of standards, that is, the extent to which quantitative criteria contained in the different guidances and regulations for radionuclides and hazardous chemicals in the environment correspond to similar health risks to the public (for example, Overy and Richardson 1995; Taylor 1995; GAO 1994; Brown 1992; EPA-SAB 1992; Kocher and Hoffman 1992; Remick 1992; Kocher and Hoffman 1991 Kocher 1988; Travis and others 1987~. In discussing the risks corresponding to

GUIDANCES AND REGULA TIONS FOR NORM Table 7.2. Lifetime cancer risks corresponding to selected radiation exposures and EPA guidances and regulations for controlling exposures of the publics 143 Risk ~| 4x 10-2 Mill tailings standards (cleanup of contaminated land and buildings) 0.2-3 x 1 o-2 Concentration of radon in homes of 150 Bq/m3 (EPA and DHHS 1 994)b 2 x 1 o-2 Annual dose equivalent to whole body from external exposure to all controlled sources combined of 5 mSv (existing FRC guidance) 1 x 10-2 Average annual effective dose equivalent from exposure to natural background radiation, including indoor radon, of 3 mSv (NCRP 1 987a) Average indoor radon concentration of 50 Bq/m3 (EPA and DHHS 1 994)b 0.7-9 x 10-3 4x 10-3 Annual effective dose equivalent from all controlled sources combined, excluding indoor radon, of 1 mSv (proposed federal guidance) 4x 10-3 Indoor gamma radiation level of 20 pR/h and indoor residence time of RSo/O ,~ 2x 10-3 Concentrations of 226Ra in soil of 0.2 Bq/g in top 15 cm and 0.6 Bq/g below 15 cm and continuous external exposure indoors and outdoors 9x 104 Annual dose equivalent to whole body of 0.25 mSv Sx 104 Annual effective dose equivalent of 0.15 mSv 4x 104 Annual effective dose equivalent of 0.1 mSv 2 x 10 ~ Concentration of uranium in drinking water of 20 ,ug/L 2 x 10 ~ Concentration of 226Ra in drinking water of 0.2 Bq/L 1 x 10- Goal for cleanup of radioactively contaminated sites (CERCLA and NCP) 1 x 10 ~ Annual effective dose equivalent of 0.04 mSv (proposed drinking-water standard for beta- or gamma-emitting radionuclides)

144 Table 7.2. (continued) GUIDELINES FOR EXPOSURE TO TENORM . l Risk | Exposure or guide lice or regulation l 1 x 10- Annual dose equivalent to lungs from inhalation of insoluble natural uranium of 0.25 mSv (uranium fuel-cycle standards) 4 x 10-5 Annual dose equivalent to bone surfaces Mom ingestion of soluble natural uranium of 0.25 mSv (uranium fuel-cycle standards) 3 x 10-8 Containment requirements for disposal of spent fuel, high-level waste, . and transuranic waste (average risk in US population) aValues assume continuous exposure over 70 y and, unless otherwise noted, risk of fatal cancers per unit effective dose equivalent of 5 x 1O-s per millisievert (EPA 1994c; NCRP 1993a; ICRP 1991). blower bound for risk applies to individuals who have never smoked, and upper bound applies to smokers; for former smokers, risk may lie in between. different guidances and regulations, various investigators have developed tables similar to table 7.2 (for example, GAO 1994; Kocher 1988; Travis and others 1987~. As noted earlier, the comparisons have indicated that the risks corresponding to different guidances and regulations vary considerably, and some investigators have concluded that a consensus on acceptable risk is lacking (GAO 1994~. The desire for consistency in regulations is understandable. However, several factors indicate that it is unreasonable to expect it, including differences in statutory and judicial mandates, differences in the primary bases of standards, differences in the applicability of standards, differences in population groups of primary concern, and differences in considerations of natural background. The discussions of these and other factors in the following sections are concerned with guidances and regulations for radiation exposure of the public, but some also apply to regulation of hazardous chemicals.

GUIDANCES AND REGULA TIONS FOR NORM Differences in Statutory and Judicial Mandates 145 A fundamental reason why the health risks corresponding to some of the guidances and regulations for radionuclides in the environment appear to be inconsistent is that the standards were developed under different laws that mandate different approaches to standard-setting. In particular, the traditional approach to establishing radiation standards under authority of the Atomic Energy Act is fundamentally different from the approach used in establishing radiation standards under the authority of other laws that are concerned primarily with exposures to hazardous chemicals (Overy and Richardson 1995; Kocher and Hoffman 1992, 1991~. The Atomic Energy Act provides the authority for regulation of radiation exposures of the public that arise, either directly or indirectly, from operations of the nuclear fuel cycle for peaceful or defense purposes. The traditional approach to radiation protection under the Atomic Energy Act has the following two basic elements, given that the exposures are justified: · A limit (upper bound) on acceptable dose (and therefore risk), meaning that doses above the limit are regarded as intolerable. · Reduction of doses (and risks) below the limit to as low as reasonably achievable (ALARA). Those elements are an essential aspect of current recommendations on radiation protection developed by the ICRP (1991) and NCRP (1993a) and they are embodied in EPA's proposed federal guidance on radiation protection of the public (EPA 1994d), which applies to all controlled sources combined except indoor radon and medical exposures, and in regulations for specific sources or practices, including operations of uranium fuel-cycle facilities (40 CFR Part 190) and management and disposal of spent fuel, high-level waste, and transuranic waste (40 CFR Part 191~. The approach to controlling radiation exposures of the public under the authority of other environmental laws is, in many cases, quite the opposite of the approach to radiation protection under the Atomic Energy Act described above (Kocher and Hoffman 1992, 1991~. Specifically, the approach under other laws often has the following two basic elements: · A goal for acceptable risk. · Allowance for an increase (relaxation) in risks above the goal on the basis, for example, of technical feasibility and cost.

146 GUIDELINES FOR EXPOSURE TO TENORM Those elements are embodied, for example, in the requirements of the Safe Drinking Water Act and CERCLA and their implementing regulations. The Safe Drinking Water Act essentially sets a goal of zero risk to the public posed by exposure to radionuclides and other carcinogens in drinking water, but the goal clearly cannot be achieved at any cost. The act then requires that the legally enforceable standards (MCLs) be set as close to the goal of zero risk as possible, with technical feasibility and costs of removing radionuclides from public drinking-water supplies taken into account. The requirements of CERCLA and its implementing regulations (40 CFR Part 300) include compliance with ARARs and a lifetime cancer risk of 10-4 as goals for remediation of contaminated sites (Luftig and Weinstock 1997; Clay 1991), but these goals can be relaxed on the basis of many considerations, including that achieving the goals is not feasible. It cannot be overemphasized that the concept of a limit, as embodied in radiation protection standards for the public developed under the Atomic Energy Act, is fundamentally different from the concept of a goal, as embodied in radiation standards developed under some other environmental laws. A goal for acceptable risk does not define any kind of a limit on acceptable (tolerable) risk that must be met without regard for cost or other relevant factors. Therefore, it is potentially misleading, and could be inappropriate, to compare quantitative criteria in the form of limits with criteria that are goals. For example, it is not particularly meaningful to compare the limit on lifetime cancer risk of about 4 x 10-3 corresponding to the primary dose limit of 1 mSv (100 mrem) per year for exposure over 70 years in EPA's proposed federal guidance on radiation protection of the public with the risk goal of 10-4 for cleanup of contaminated sites under CERCLA unless the fundamental difference in concept between the two is recognized. An example of the importance of a judicial mandate in establishing standards is provided by the standards for airborne emissions of radionuclides developed under the Clean Air Act. The court of appeals mandated that the standards be based on considerations of acceptable risks to the public, whereas other standards for specific sources or practices developed by EPA have been based primarily on considerations of the achievability of risks (cost-benef~t analysis). However, the standards developed under the Clean Air Act are reasonably consistent with most other standards that were based on the achievability of risks, in part because the lifetime risks of about 10-4 to 10-6 judged by EPA to be acceptable for airborne emissions also were reasonably achievable and because the risks judged by EPA to be acceptable for airborne emissions were comparable with the risks corresponding to other standards that were based on the achievability of risks.

GUIDANCES AND REGULATIONS FOR NORM Differences in Primary Bases of Standards 147 As discussed earlier, some radiation standards were based primarily on judgments about acceptable health risks to the public, and others primarily on judgments about the achievability of risks. There is no a priori reason to expect that risks corresponding to the two types of standards would be consistent. The importance of the different bases of standards is illustrated by a comparison of EPA's proposed federal guidance on radiation protection of the public with the standards for radionuclides in drinking water. As indicated in table 7.2, the drinking-water standards for naturally occurring radionuclides correspond to lifetime risks of about 10-4, whereas the primary dose limit of 1 mSv (100 mrem) per year in the proposed federal guidance corresponds to a lifetime risk of about 4 x 10-3. The primary dose limit is based on an assumption about the maximum acceptable (tolerable) risk posed by radiation exposure whereas the drinking-water standards (MCLs) are based essentially on a cost- benefit analysis of removal of radionuclides from public drinking-water supplies. In general, standards based primarily on risks judged to be acceptable should not be compared with standards based primarily on risks judged to be reasonably achievable unless the difference between the two concepts is recognized. Differences in Applicability of Standards In many cases, the risks corresponding to various guidances and regulations appear to be inconsistent essentially because the standards differ in their applicability. Some of the ways in which differences in the applicability of standards are important are discussed below. Perhaps the most important difference in the applicability of standards is shown by a comparison of EPA's proposed federal guidance on radiation protection of the public-specifically, the primary dose limit of 1 mSv (lOOmrem) per year, which applies to all controlled sources of exposure combined except for indoor radon and medical exposures with any other EPA guidances or regulations developed under any environmental laws, which apply only to specific sources or practices. A standard for all sources of exposure combined is not directly comparable with standard for a specific practice or source. Indeed, except for indoor radon, the risks corresponding to standards for specific sources or practices should be substantially less in most cases than the risk corresponding to the primary dose limit for all sources combined (EPA 1994d). In this regard, it should be noted that no guidance or regulation for hazardous chemicals specifies a limit on risk posed by exposure to all controlled sources combined. That is, for hazardous chemicals, there is no standard analogous to the primary dose limit in radiation-protection standards; rather, all

148 GUIDELINES FOR EXPOSURE TO TENORM standards for hazardous chemicals in the environment apply only to specific exposure situations. Furthermore, for any particular situation (such as contaminants in drinking water or airborne emissions of hazardous air pollutants), hazardous chemicals often have been regulated only individually. A second important difference is that the various standards for specific sources or practices apply to different exposure situations. Most standards for specific sources or practices were based primarily on judgments about environmental levels, releases, or doses (and therefore risks) that are reasonably achievable for the exposure situations of concern (application of the ALARA objective). There is no a priori reason to expect risks judged reasonably achievable for one exposure situation (such as releases from operating nuclear facilities) to be consistent with risks judged reasonably achievable for a different situation (such as radioactive waste disposal). Indeed, it is primarily in the interest of achieving some degree of consistency in regulation that the quantitative criteria contained in standards that apply to different exposure situations often are about the same. A third important difference is that standards developed under the Atomic Energy Act generally apply to all release and exposure pathways combined for the exposure situations of concern, whereas standards developed under other environmental laws often apply only to particular release and exposure pathways. For example, the dose constraint for operations of uranium fuel-cycle facilities (40 CFR Part 190) developed under the Atomic Energy Act applies to all release and exposure pathways, whereas standards for radioactivity in drinking water developed under the Safe Drinking Water Act (40 CFR Part 141) apply only to a single environmental medium (water) and a single exposure pathway, and standards developed under the Clean Air Act (40 CFR Part61) apply only to airborne releases. The one exception for standards developed under laws other than the Atomic Energy Act is the cancer-risk goal of 10-4 for remediation of contaminated sites under CERCLA (40 CFR Part 300~; in this case, the goal applies to all release and exposure pathways combined at a particular site. In general, it should not be expected that the risks corresponding to standards that apply only to a single release or exposure pathway would be consistent with the risks corresponding to standards that apply to all release and exposure pathways combined. Differences in Population Groups of Primary Concern Some standards are concerned primarily with protection of maximally exposed individuals; others are concerned primarily with protection of whole populations, that is, individuals in the population receiving an average exposure. For a given exposure situation, doses and risks for maximally exposed

GUIDANCES AND GULL TIONS FOR NOW 149 individuals generally will be higher than those for average individuals in the population. Therefore, the standards might differ substantially depending on the population group of primary concern. Examples of standards that are concerned primarily with protection of maximally exposed individuals include the dose constraints in standards for operations of uranium fuel-cycle facilities (40 CFR Part 190) and management and disposal of spent fuel, high-level waste, and transuranic waste (40 CFR Part 191~. Another example is the risk goal of 10-4 in standards for cleanup of contaminated sites under CERCLA (40 CFR Part300~. The standards for airborne emissions of radionuclides (40 CFR Part 61) took into account both the maximum individual risk and the average risk in the exposed population, but the dose constraint that applies to many sources is concerned primarily with protection of maximally exposed individuals. The clearest example of a standard that is concerned with protection of whole populations, rather than maximally exposed individuals, is the containment requirements for disposal of spent fuel, high-level waste, and transuranic waste (40 CFR Part 191~. The limits on cumulative releases of radionuclides over 10,000 y were based on an assumed number of health effects in the entire US population, without regard for risks to individuals who might reside near disposal sites, which are limited by a separate dose constraint. The drinking-water standards for radionuclides (40 CFR Part 141) also are concerned with protection of whole populations because the standards were derived on the basis of a cost-benef~t analysis in which all individuals were assumed to ingest the same amount of drinking water. Another example of the importance of the population group of concern in establishing standards is provided by current guidances on mitigation of radon in homes, specifically the EPA action level of lSOBq/m3 (4pCi/L) compared with the NCRP-recommended action level of about 370 Bq/m3 (10 pCi/L) discussed in chapter 8. EPA and NCRP both were concerned with mitigation of risks to the relatively few individuals who reside in homes in which the levels of radon greatly exceed the US average. However, the two organizations arrived at different action levels largely because EPA also was concerned with reduction of exposures in the greatest number of homes, and EPA developed its action level on the basis of a cost-benefit analysis for reduction of levels of indoor radon in all homes. Differences in Considerations of Natural Background In some cases, the health risks corresponding to various guidances and regulations appear to be inconsistent essentially because some standards are concerned with exposures to naturally occurring radionuclides and others are not. Given the relatively high doses and risks posed by exposure to natural

150 GUIDELINES FOR EXPOSURE TO TENORM background radiation (see chapter 2), the risks corresponding to various guidances and regulations can differ substantially depending on whether the standards include exposures to natural background. The clearest examples of the importance of natural background in establishing standards are the regulations for control and cleanup of residual radioactive materials at uranium and thorium mill tailings sites (40 CFR Part 192) and the federal guidance on indoor radon (EPA and DHHS 1994~. Both standards are concerned with exposures to naturally occurring radionuclides that have been increased by human activities, and knowledge of background levels of naturally occurring radionuclides was important in developing the standards. In either case, background levels result in relatively high doses and risks, and it clearly is impractical for the standards to require reductions in concentrations to levels below background. Therefore, it is reasonable that the risks corresponding to the mill tailings standards and the guidance on indoor radon are considerably higher than the risks corresponding to other standards that do include contributions from natural background, such as standards for operations of uranium fuel-cycle facilities (40 CFR Part 190) and waste management and disposal (40 CFR Part 191~. Other Considerations in Comparing Standards Two additional factors have resulted in differences in risks corresponding to various guidances and regulations for controlling radiation exposures of the public. First, the various guidances and regulations were developed at different times, and judgments about the acceptability of doses and risks have changed considerably over time. For example, when the standards for operations of uranium fuel-cycle facilities (40 CFR Part 190) were developed in the middle 1970s, the primary dose limit for all controlled sources combined was 5 mSv (SOOmrem) per year (FRC 1961; FRC 1960), the risk of fatal cancers was assumed to be about 1 x 1O-s per millisievert (ICRP 1977), and standards for radionuclides and hazardous chemicals developed under environmental laws other than the Atomic Energy Act had not been issued or did not yet have an influence on radiation standards developed under the Atomic Energy Act. Since then, the primary dose limit for all controlled sources combined has been reduced to 1 mSv (100 mrem) per year, the assumed risk of fatal cancers has increased to 5 x 1O-s per millisievert (EPA 1994c, NCRP 1993a; ICRP 1991), and a judgment by EPA that a lifetime risk of about 10- is an upper bound on acceptable risk for specific sources or practices has been increasingly incorporated into radiation standards on the basis of precedents in regulations developed under other environmental laws (such as the Safe Drinking Water Act, the Clean Air Act, CERCLA). Thus, there has been a tendency in recent

GUIDANCES AND REGULA TIONS FOR NORM 151 years to develop increasingly stringent radiation standards, as illustrated by EPA's use of a dose constraint of 0.15 mSv (15 mrem) or 0.1 mSv (10 mrem) per year, in contrast with the earlier use of a dose constraint of 0.25 mSv (25 mrem) per year. Second, the dosimetric quantities used in radiation standards have changed over time. The earliest standards were expressed in terms of dose to the whole body or the critical organ. A weakness of this approach is that the dose criteria generally do not correspond well to a particular risk, especially for nonuniform irradiations of the body. However, later standards are expressed in terms of the effective dose equivalent, which was intended to be proportional to risk for any uniform or nonuniform irradiations of the body (ICRP 1977~. The differences between organ doses and the effective dose equivalent are important mainly for ingestion and inhalation exposures. For most radionuclides, the effective dose equivalent per unit activity intake is substantially less than the dose to the critical organ; furthermore, the ratio of the two doses depends on the particular radionuclide (Eckerman and others 1988~. But those differences are important only if dose criteria are compared; they are not important when the corresponding risks are compared, provided that conversion of organ dose to risk takes into account the dose in all tissues irradiated. Summary of Issues of Consistency of Standards There are several important reasons why the risks corresponding to the many guidances and regulations for controlling radiation exposures of the public appear to be inconsistent and why it is unreasonable to expect the risks to be consistent. The considerable variability in risks embodied in the various guidances and regulations is explained in large part by differences in legislative and judicial mandates for setting standards, differences in the primary bases of standards, differences in the exposure situations to which the standards apply, differences in the population groups of primary concern, and differences in the accounting of natural background radiation. The important conclusion to be drawn from these discussions is that risks corresponding to different guidances and regulations should not be compared unless the bases of the standards and their applicability are well understood and the standards are interpreted properly. Otherwise, inappropriate and misleading conclusions about the meaning of differences in risks embodied in the standards can result.

152 GUIDELINES FOR EXPOSURE TO TENORM RELATIONSHIP BETWEEN STANDARDS AND DOSES EXPERIENCED Previous discussions in this chapter and chapter 5 have addressed the primary bases of standards (limits on levels of radionuclides in environmental media, releases to the environment, doses, or risks) in guidances and regulations for controlling radiation exposures of the public and the consistency of the standards with regard to the corresponding lifetime risks. This section considers the important question of the relationship between the standards and the doses and risks that would be experienced by exposed individuals and populations. These considerations provide important insights into the single unifying principle namely, the ALARA objective-that is the most important in determining actual risks, irrespective of the differences in risks corresponding to the various quantitative criteria in guidances and regulations. A discussion of the quantitative criteria in guidances and regulations that does not consider other factors that are important in controlling exposures of the public gives the impression that the criteria by themselves defame acceptable risks. That impression is misleading. Irrespective of the particular environmental law under which any guidance or regulation is developed, the doses and risks experienced by exposed individuals and populations are not determined primarily by compliance with the quantitative criteria alone. This important point is illustrated in the following paragraphs. EPA's proposed federal guidance on radiation protection of the public (EPA 1994d) incorporates the three basic principles of radiation protection set forth by ICRP (1991) and NCRP (1993a): · Justif cation of exposures (positive net benefit). · Reduction of exposures of individuals and populations to as low as reasonably achievable (ALARA), economic and social factors being taken into account, also referred to as optimization of exposures (ICILY 1991; 1977~. · Limitation of dose to individuals from all controlled sources combined. The ALARA objective is implemented in part by establishing standards for specific sources or practices that limit doses for the exposure situations of concern to a fraction of the dose limit for all controlled sources combined, and further site-specific reductions in dose based on ALARA considerations

GUIDANCES AND ~GUlATIONS FOR NOW 153 generally are required. The important point is that the ALARA objective essentially defines a site-specif~c process for dose reduction, and the result of the process generally cannot be defined and quantified in advance in regulations. The power of the ALARA objective in reducing doses to the public is seen by examining doses that result from operations of nuclear facilities that are regulated under the Atomic Energy Act. The average individual dose in exposed populations is only about 0.05% of the primary dose limit for the public of lmSv (lOOmrem) per year from all controlled sources combined (NCRP 1987a); and doses to individuals who receive the highest exposures normally are no more than about 10% of the primary dose limit and often are substantially less (EPA 1989d). Therefore, for the important case of releases from operating nuclear facilities, the doses and risks experienced by most members of the public are determined largely by vigorous application of the ALARA objective, but the primary dose limit and even, in many cases, the authorized limits for specific sources or practices at a fraction of the dose limit are rather unimportant in determining actual doses and risks. A similar example is provided by the requirements for cleanup of contaminated sites under CERCLA and its implementing regulations (40 CFR Part 300~. In considering acceptable risks at contaminated sites, considerable attention normally is given to the preliminary remediation goals, including the goal for lifetime cancer risk of 10-4 (Luftig and Weinstock 1997; Clay 1991~. However, far less attention has been given to the result that the negotiated cleanup levels at most sites, as incorporated in the ROD, correspond to risks substantially above the goal of 10 ~ (EPA 1994b; Baes and Marland 1989~. The actual cleanup levels judged to be acceptable at any site are based on a decision process that is similar to applications of the ALARA objective under the Atomic Energy Act. Therefore, for the important case of cleanup of contaminated sites, the acceptable risks at any site are determined primarily by site-specif~c application of the ALARA objective, not by the risk goal specified in regulations. Another example is provided by the standards for radioactivity in drinking water (40 CFR Part 141) developed under the Safe Drinking Water Act. These standards are important because they apply to drinking-water systems used by more than half the US population and generally are being applied to protection of groundwater resources at new waste-disposal sites and at contaminated sites undergoing remediation. Although the standards specify limits (MCLs) on allowable radioactivity in community drinking-water systems, it is important to emphasize that the MCLs were based on judgments about levels of radioactivity that could be achieved, given existing levels in sources of drinking water throughout the United States and the effectiveness of available methods for water treatment, rather than an a priori judgment about acceptable

154 GUIDELINES FOR EXPOSURE TO TENORM risks posed by drinking water. Therefore, the MCLs are based essentially on ALARA considerations. Furthermore, the drinl~ing-water standards are subject to change periodically on the basis of reconsideration of the costs and benefits of water treatment (EPA l 991 a). These discussions illustrate the following important points. Although guidances and regulations for controlling radiation exposures of the public contain quantitative criteria that define limits or goals for acceptable doses or risks for the exposure situations of concern, the doses and risks that would be experienced by individuals and populations are, in most cases, not determined by these criteria. For most important exposure situations, actual doses and risks that would be experienced are determined primarily by application of an ALARA process, whose outcome generally cannot be quantified in regulations. In most cases, actual limits or goals for dose or risk specified in guidances and regulations, although they represent important statements of principle and although they define an upper or lower bound on dose or risk for applying the ALARA objective, are relatively unimportant in determining actual outcomes. Viewed in that way, all guidances and regulations for controlling radiation exposures of the public developed under any laws have as their unifying principle the objective that exposures from any source or practice should be as low as reasonably achievable (ALARA). To the extent that the ALARA objective is applied consistently in all cases and it is recognized that doses and risks that are ALARA can vary considerably depending on the particular source or practice, all guidances and regulations will be consistent with regard to doses and risks actually experienced. SUMMARY This chapter has reviewed EPA's existing or proposed guidances and regulations that apply to control of routine exposures of the public to naturally occurring radionuclides. No particular distinction has been made in this review between standards for naturally occurring radionuclides associated with operations of the nuclear fuel cycle, which are developed under the Atomic Energy Act, and standards for TENORM, which are developed under environmental laws other than He Atomic Energy Act and are the main concern of this study. This review has emphasized the standards that apply to naturally occurring radionuclides and the bases of the guidances or regulations. This chapter also discussed the health risks corresponding to the quantitative criteria in the guidances and regulations that apply to naturally occurring radionuclides. The risks corresponding to the different guidances and regulations vary over several orders of magnitude, owing primarily to:

G UIDANCES AND REG ULA TIONS FOR NORM · Differences in statutory and judicial mandates for standards, especially the difference between the traditional regulatory approach under the Atomic Energy Act, which emphasizes a limit on radiation dose and reduction in doses below the limit to as low as reasonably achievable (ALARA), and the regulatory approach under other environmental laws. These laws often emphasize a goal for risk and allowance for an increase (relaxation) in risks above the goal based primarily on technical feasibility and cost. · Differences in the primary bases of standards, that is, the consideration that some standards are based primarily on an a priori judgment about risks that are acceptable whereas other standards are based primarily on a judgment about risks that are reasonably achievable. · Differences in the applicability of standards, especially the considerations that some standards apply to all sources of exposure combined, whereas other standards apply only to specific sources or practices. The various standards for specific sources or practices apply to different exposure situations with different risks that are reasonably achievable. · Differences in the population groups of primary concern in developing standards, particularly whether the standards emphasize protection of maximally exposed individuals or protection of individuals who receive the average dose in exposed populations. · Differences in the considerations of natural background, especially whether background levels of radioactivity are important in establishing the standards. 155 It is important to understand those factors when judging the meaning of differences in health risks corresponding to the various guidances and regulations. An important conclusion from the discussions in this chapter is that the large differences in health risks corresponding to the various EPA guidances and regulations do not necessarily mean that the different standards are inconsistent with regard to defining an acceptable risk to individuals or populations. Without regard for the differences in standards, as summarized above, the principle that exposures of individuals and populations should be ALARA is the most important factor in determining risks actually experienced for any controllable exposure situation. That is, largely without regard for the limits or goals

156 GUIDELINES FOR EXPOSURE TO TENORM specified in various guidances and regulations, application of the ALARA objective is the most important factor in determining acceptable risks. Therefore, to the extent that the ALARA objective is applied consistently to all exposure situations, all guidances and regulations would be consistent with regard to risks actually experienced, provided that it is also recognized that risks that are ALARA can vary considerably depending on the particular exposure situation.

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Naturally occurring radionuclides are found throughout the earth's crust, and they form part of the natural background of radiation to which all humans are exposed. Many human activities-such as mining and milling of ores, extraction of petroleum products, use of groundwater for domestic purposes, and living in houses-alter the natural background of radiation either by moving naturally occurring radionuclides from inaccessible locations to locations where humans are present or by concentrating the radionuclides in the exposure environment. Such alterations of the natural environment can increase, sometimes substantially, radiation exposures of the public. Exposures of the public to naturally occurring radioactive materials (NORM) that result from human activities that alter the natural environment can be subjected to regulatory control, at least to some degree. The regulation of public exposures to such technologically enhanced naturally occurring radioactive materials (TENORM) by the US Environmental Protection Agency (EPA) and other regulatory and advisory organizations is the subject of this study by the National Research Council's Committee on the Evaluation of EPA Guidelines for Exposures to Naturally Occurring Radioactive Materials.

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