United States ';- j ; Environmental Protection Agency : ; Ai,r And Radiation (660tJX-V.V,; v January i98 Health Risks From Low-Level Environmental Exposure To Radionuclides Federal Guidance Report No. 13 - Part 1 Interim Version ------- ------- Federal Guidance Report No. 13 Part I - Interim Version HEALTH RISKS FROM LOW-LEVEL ENVIRONMENTAL EXPOSURE TO RADIONUCLIDES Radionuclide-Specific Lifetime Radiogenic Cancer Risk Coefficients for the U.S. Population, Based on Age-Dependent Intake, Dosimetry, and Risk Models Keith F. Eckerman Richard W. Leggett Christopher B. Nelson Jerome S. Puskin Allan C. B. Richardson Oak Ridge National Laboratory Oak Ridge, Tennessee 37831 Office of Radiation and Indoor Air United States Environmental Protection Agency Washington, DC 20460 1998 ------- ------- PREFACE The Federal Radiation Council (FRC) was formed in 1959, through Executive Order 10831. A decade later its functions were transferred to the Administrator of the newly formed Environmental Protection Agency (EPA) as part of Reorganization Plan No. 3 of 1970. Under these authorities it is the responsibility of the Administrator to "advise the President with respect to radiation matters, directly or indirectly affecting health, including guidance for all Federal agencies in the formulation of radiation standards and in the establishment and execution of programs of cooperation with States." The purpose of this guidance is to ensure that the regulation of exposure to ionizing radiation is adequately protective, reflects the best available scientific information, and is carried out hi a consistent manner. Since the mid-1980s EPA has issued a series of Federal guidance documents for the purpose of providing the Federal agencies technical information to assist their implementation of radiation protection programs. The first report in this series, Federal Guidance Report No. 10 (EPA, 1984a), presented derived concentrations of radioactivity in air and water corresponding to the limiting annual doses recommended for workers in 1960. That report was superseded in 1988 by Federal Guidance Report No. 11 (EPA, 1988), which provided dose coefficients for internal exposure of members of the general public and limiting values of radionuclide intake and air concentrations for workers, based on updated biokinetic and dosimetric models. Federal Guidance Report No. 12 (EPA, 1993) tabulated dose coefficients for external exposure to radionuclides in air, water, and soil. When final, this report is intended to promote consistency in assessments of the risks to health from radiation by Federal agencies and others and to help ensure that such assessments are based on sound scientific information. It is intended as the first of a set of documents, referred to collectively as Federal Guidance Report No. 13, that will address risks to health from exposure to specific radionuclides. These documents will make use of state-of-the-art methods and models for estimating the risks to health from internal or external exposure. These methods and models take into account, for the first time in a comprehensive compilation, the age and gender-specific aspects of radiation risk. This interim version of Federal Guidance Report No. 13, Part I, provides tabulations of risk estimates, or "risk coefficients", for cancer attributable to exposure to any of approximately 100 important radionuclides through various environmental media. These risk coefficients apply to populations that approximate the age, gender, and mortality experience characterized by the 1989-91 U.S. decennial life tables. The tabulations in the final version of Part I will extend the methodology of the interim version to the other radionuclides included in Federal Guidance Reports 11 and 12. Subsequent parts of Federal Guidance Report No. 13 may extend the in ------- exposure pathways, and health endpoints addressed. As necessary, these publications will be reissued to update the information provided. EPA has chosen to issue Part I of Federal Guidance Report No. 13 as an interim report at this time in order to provide governmental agencies and other interested parties an opportunity to become familiar with it and its supporting methodology and to provide comments for the Agency's consideration before publishing the final version. In this report, the risk coefficient for exposure to a given radionuclide through a given environmental medium is expressed as the probability of radiogenic cancer mortality or morbidity per unit activity inhaled or ingested, for internal exposure, or per unit time-integrated activity concentration in air or soil, for external exposure. These risk coefficients may be applied to either chronic or acute exposure to environmental radionuclides. That is, a risk coefficient may be interpreted either as average risk per unit exposure for persons exposed throughout life to a constant activity concentration of a radionuclide in an environmental medium, or as average risk per unit exposure for persons acutely exposed to the radionuclide through the environmental medium, as long as the exposure involved is properly characterized as low acute dose or low dose rate. In this report, "low dose" and "low dose rate" are defined in terms of the range of applicability of the radiogenic risk models applied, rather than as regulatory concepts. The risk estimates tabulated in this report are intended mainly for prospective assessments of estimated cancer risks from long-term exposure to radionuclides in environmental media. For example, it is anticipated that this document will be used in such activities as preparation of environmental impact statements and development of assessments in support of generic rule making for control of radiation exposure. While it is recognized that these risk coefficients are likely also to be used in retrospective analyses of radiation exposures of populations, it is emphasized that such analyses should be limited to estimation of total or average risks in large populations. The tabulations are not intended for application to specific individuals or to age or gender subgroups, for example, children, and should not be used for that purpose. Also, these risk coefficients are based on radiation risk models developed for application either to low acute doses or low dose rates. Thus, these risk coefficients should not be applied to accident cases involving high doses and dose rates, either in prospective or retrospective analyses. Finally, some risk assessment procedures are established as a matter of policy, and additional steps may be needed before using these risk coefficients. For example, EPA recommends that radiation risk assessments for sites on the National Priorities List under the Comprehensive Environmental Response, Compensation, and Liability Act be performed using the Health Effects Assessment Summary Tables (HEAST), which are periodically updated to reflect new information. IV ------- Documents in EPA's Federal Guidance Report series provide reference values for assessing both radiation dose and risk from exposure to radionuclides. Federal Guidance Report Nos. 11 and 12, which address radiation dose, are intended for use in determining conformance with the radiation protection guidance to Federal agencies issued by the President. The present report does not replace either of those documents or affect their use for radiation protection purposes, even though many of the biokinetic and dosimetric models used here are updates of models used in Federal Guidance Report No. 11. The dose coefficients in Federal Guidance Report Nos. 11 and 12 continue to be recommended for determinations of compliance with dose-based regulations and, where applicable, for use in dose assessments. Those reports will be updated in the future as warranted. Federal Guidance Report 13 has a different purpose it is intended for use in assessing risks from radionuclide exposure, in a variety of applications ranging from analyses of specific sites to the general analyses that support a rule making. Although its use, especially by Federal agencies, is encouraged to promote consistency in risk assessment, such use is, of course, discretionary. This report would not have been possible without the contributions of the many investigators who produced the building blocks that provided the basis for the results presented here. These include: Jerome S. Puskin and Christopher B. Nelson, who assembled the models for age-dependent, organ-specific cancer risks; Richard W. Leggett, Keith F. Eckerman and many other contributing scientists who developed and compiled the age-specific biokinetic and dosimetric models published by the International Commission on Radiological Protection; Robert Armstrong, who supplied pre- publication values for the 1989-91U.S. decennial life tables; and Keith F. Eckerman and Richard W. Leggett, who provided the basis for calculation of doses from internal and external exposure. Allan C.B. Richardson initiated preparation of this, as well as Reports 10, 11, and 12, and provided guidance on its broad outline. The major effort required to prepare the report itself was carried out by Keith F. Eckerman, Richard W. Leggett, Christopher B. Nelson, Jerome S. Puskin, and Allan C.B. Richardson. Technical review was contributed by William J. Bair, Bernd Kahn, Charles E. Land, John R. Mauro, and Alan Phipps. Preparation of the report was funded by the U.S. Environmental Protection Agency, U.S. Department of Energy (DOE), and U.S. Nuclear Regulatory Commission (NRC). Its technical content has been reviewed by these agencies. We gratefully acknowledge the work of the authors, the agencies who contributed funding for this work, and the helpful comments by technical reviewers of this interim version of the report. We would appreciate receiving any comments by June 30, 1998, so that they may be taken into ------- account in the final version, currently planned for publication in the fall of 1998. Comments should be addressed to Allan C. B. Richardson, Associate Director for Radiation Guidance, Radiation Protection Division (6602J), U.S. Environmental Protection Agency, Washington, DC 20460. Lawrence G. Weinstock, Acting Director Office of Radiation and Indoor Air VI ------- CONTENTS PREFACE iii CHAPTER 1. INTRODUCTION 1 Radionuclides and exposure scenarios addressed 2 Applicability to the current U.S. population 4 Computation of the risk coefficients for internal exposure 5 1. Lifetime risk per unit absorbed dose at each age 5 2. Absorbed dose rates as a function of time post acute intake at each age 6 3. Lifetime cancer risk per unit intake at each age 7 4. Lifetime cancer risk for chronic intake 7 5. Average lifetime cancer risk per unit activity intake 8 Computation of the risk coefficients for external exposure 8 How to apply a risk coefficient 9 Limitations on use of the risk coefficients 10 Uncertainties in the biokinetic, dosimetric, and radiation risk models 10 Software used to compute the risk coefficients 11 Organization of the report 11 CHAPTER 2. TABULATIONS OF RISK COEFFICIENTS 13 Risk coefficients for inhalation 13 Risk coefficients for ingestion 14 Ingestion of tap water 14 Ingestion of food 15 Risk coefficients for external exposure 15 Adjustments for current age and gender distributions in the U.S 16 CHAPTERS. EXPOSURE SCENARIOS 47 Characteristics of the exposed population 47 Growth of decay chain members 47 Inhalation of radionuclides 48 Intake of radionuclides in food 52 Intake of radionuclides in tap water 53 External exposure to radionuclides in air 53 External exposure to radionuclides in soil 53 CHAPTER 4. BIOKINETIC MODELS FOR RADIONUCLIDES 55 The respiratory tract 55 The gastrointestinal tract 57 Systemic biokinetic models 58 Treatment of decay chain members formed in the body 64 vn ------- Solution of the biokinetic models 66 Uncertainties in the biokinetic models 66 CHAPTER 5. DOSIMETRIC MODELS FOR INTERNAL EMITTERS 71 Age-dependent masses of source and target regions 71 Dosimetric quantities 74 Nuclear decay data , 75 Specific absorbed fractions for photons 75 Absorbed fractions for electrons 76 Absorbed fractions for alpha particles and recoil nuclei 77 Spontaneous fission 77 Computation of SE 78 Uncertainties in the internal dosimetric models 78 SEs for photons 78 SEs for beta particles and discrete electrons 79 SEs for alpha particles 80 Special dosimetric problems presented by walled organs 81 CHAPTER 6. DOSIMETRIC MODELS FOR EXTERNAL EXPOSURES 83 Interpretation of dose coefficients from Federal Guidance Report No. 12 83 Nuclear data files used 84 Radiations considered 85 Effects of indoor residence 86 Uncertainties in external dose models 86 Transport of radiation from the environmental source to humans 86 Effects of shielding during indoor residence 87 Effects of age and gender 88 CHAPTER?. RADIOGENIC CANCER RISK MODELS 91 Types of risk projection models 91 Epidemiological studies used in the development of risk models 93 Modification of epidemiological data for application to low doses and dose rates 93 Relative biological effectiveness factors for alpha particles 94 Risk model coefficients for specific organs 94 Association of cancer type with dose location 98 Relation between cancer mortality and morbidity 99 Treatment of discontinuities in risk model coefficients 102 Uncertainties in risk models 102 Sampling variability 102 Diagnostic misclassification 103 Errors in dosimetry 103 Uncertainties in the shape of the dose-response curve 104 viii ------- Uncertainties in the RBE for alpha particles 106 Uncertainties in transporting risk estimates across populations 108 Uncertainties in age and time dependence of risk per unit dose 109 Uncertainties in site-specific cancer morbidity risk estimates 110 Computation of radionuclide risk coefficients 110 APPENDIX A. MODELS FOR MORTALITY RATES FOR ALL CAUSES AND FOR SPECIFIC CANCERS A-l APPENDIX B. ADDITIONAL DETAILS OF THE DOSIMETRIC MODELS B-l Definitions of special source and target regions B-l Age-dependent masses of source and target regions B-2 Absorbed fractions for radiosensitive tissues in bone B-2 APPENDIX C. AN ILLUSTRATION OF THE MODELS AND METHODS USED TO CALCULATE RISK COEFFICIENTS FOR INTERNAL EXPOSURE .... C-l Gastrointestinal tract model and;/} values C-l Respiratory tract model C-2 Biokinetics of absorbed thorium C-4 Structure of the systemic biokinetic model for thorium C-4 Parameter values for the systemic model for thorium C-6 Predicted differences with age in systemic biokinetics of thorium C-8 Treatment of 232Th chain members produced in systemic tissues C-9 Comparison of updated and previous systemic models for thorium C-l 1 Conversion of activity to estimates of dose rates to tissues C-l 3 S£ values C-13 Use of SE values to calculate dose rates C-16 Conversion of dose rates to estimates of radiogenic cancers C-l 8 Comparison with risk estimates based on effective dose C-22 APPENDIX D. ADJUSTMENT OF RISK COEFFICIENTS FOR SHORT-TERM EXPOSURE OF THE CURRENT U.S. POPULATION D-l Computation of risk coefficients for the hypothetical current population D-l Comparison of coefficients for the current and stationary populations D-4 APPENDIX E. SAMPLE CALCULATIONS E-l GLOSSARY G-l REFERENCES R-l IX ------- TABLES 1.1 Radionuclides addressed in this report 3 2.1 Mortality and morbidity risk coefficients for inhalation 17 2.2 Mortality and morbidity risk coefficients for ingestion of tap water 27 2.3a Mortality and morbidity risk coefficients for ingestion of food 33 2.3b Mortality and morbidity risk coefficients for ingestion of iodine in food, based on usage of cow's milk 39 2.4 Mortality and morbidity risk coefficients for external exposure from environmental media > 41 3.1 Age- and gender-specific usage rates of environmental media, for selected ages 49 4.1a Gastrointestinal absorption fractions (/j values) for ingestion of radionuclides 59 4.1b Gastrointestinal absorption fractions (/] values) for inhalation of radionuclides 60 4.2 Systemic biokinetic models used in this report 61 4.3 Semi-quantitative assessment of the uncertainty in selected biokinetic models of the ICRP as central estimators for healthy adults 69 5.1 Source and target organs Used in internal dosimetry niethodology 72 7.1 Revised mortality risk model coefficients for cancers other than leukemia, based on the EPA radiation risk methodology (EPA, 1994) 95 7.2 Revised mortality risk model coefficients for leukemia, based on the EPA radiation risk methodology (EPA, 1994) 96 7.3 Age-averaged site^-specific cancer1 mortality risk estimates (cancer deaths per person-Gy) from low-dose, low-LET uniform irradiation of the body 99 7.4 Dose regions associated with cancer types 100 7.5 Lethality data for cancers by site in adults 101 A. 1 Gender- and age-specific Values for the survival function, S(x), and the expected remaining lifetime, °e(x)> used in this report A-2 B.I Age-specific masses (g) of source and target organs B-3 B.2 Absorbed fractions for alpha- and beta-emitters in bone (ICRP, 1979,1980) B-4 C.I Age-specific transfer coefficients (d'1) in the systemic biokinetic model for thorium (ICRP, 1995a) C-7 C.2 Predictions of 50-y integrated activity of 232Th (nuclear transformations per Bq injected), following injection into blood at age 100 d, 10 y, or 25 y C-9 C.3 Comparison of estimated 50-y integrated activities of 232Th and its decay chain members, assuming (A) independent or (B) shared kinetics of decay chain members, for the case of injection of 232Th into blood of an adult C-12 C.4 Comparison of ICRP's updated (ICRP, I995a) and previous (ICRP, 1979) models as predictors of 50-y integrated activity after acute intake of 232Th by an adult C-15 C.5 Comparison of cancer mortality risk coefficients with risk estimates based on effective dose, for ingestion (food) or inhalation of 232Th (Type M, 1 urn AMAD). . C-24 D.I Average daily usage of environmental media by the two hypothetical populations .. D-3 D.2 Comparison of risk coefficients for the two hypothetical populations D-5 ------- FIGURES 1.1 Components of the computation of risk coefficients 5 3.1 Gender-specific survival functions for the stationary population. 48 3.2 Age- and gender-specific usage rates used to derive risk coefficients for inhalation, ingestion of tap water, ingestion of food (energy intake), and ingestion of milk 50 4.1 Structure of the ICRP's respiratory tract model (ICRP, 1994a) .. 56 4.2 Model of transit of material through the gastrointestinal tract (ICRP, 1979) 57 4.3 Structure of the ICRP's biokinetic model for zirconium (ICRP, 1993) 62 4.4 Structure of the ICRP's biokinetic model for iodine (ICRP, 1989) 62 4.5 Structure of the ICRP's biokinetic model for iron (ICRP, 1995a) 63 4.6 The ICRP's generic model structure for calcium-like elements (ICRP, 1993) 65 5.1 Illustration of phantoms used to derive age-dependent specific absorbed fractions for photons 76 6.1 Estimated effects of age on effective dose for photons uniformly distributed in angle. 88 C.I Predictions of the ICRP's updated (ICRP, 1994a) and previous (ICRP, 1979) respiratory tract models, for inhalation of 232Th in soluble, moderately soluble, or insoluble 1-um particles (AMAD) .; C-3 C.2 The ICRP's generic framework for modeling the systemic biokinetics of a class of bone-surface-seeking elements, including thorium C-5 C.3 Retention of 232Th on trabecular surfaces for three ages at injection, as predicted by the updated model for thorium (ICRP, 1995a) C-8 C.4 Biokinetic model for thorium given in ICRP Publication 30 (1979) C-12 C.5 Comparison of predictions of ICRP's updated (ICRP, 1995a) and previous (ICRP, 1979) systemic biokinetic models for thorium C-14 C.6 Age-specific lvalues (high-LET) for232Th C-15 C.7 Estimated weight of red marrow as a function of age C-16 C.8 Contributions of 232Th in Trabecular Bone Surface, Trabecular Bone Volume, and Red Marrow to the high-LET dose rate to Red Marrow in the adult C-17 C.9 Estimated dose rate to Red Marrow following acute ingestion of 232Th, for three ages at ingestion C-17 C. 10 Estimated dose rates to Red Marrow following acute inhalation of moderately soluble 232Th, for three ages at inhalation ; C-17 C.I 1 Relative risk functions, T|(«, jc), for leukemia in males for three ages at irradiation .. C-19 C. 12 Age- and gender-specific mortality rates for leukemia, based on U.S. data for 1989-91 (NCHS, 1992,1993a, 1993b) C-19 C.I3 Gender-specific survival functions based on U.S. life tables for 1989-91 (NCHS, 1997) C-20 C.I4 Gender-specific lifetime risk coefficient (LRG) functions for radiogenic leukemia. . .. C-20 C. 15 Derived gender-specific risk ra (x,) of dying from leukemia due to ingestion of IBq of 232Th in food at age x, C-21 C. 16 Derived gender-specific risk ra (x;) of dying from leukemia due to inhalation of IBq of 232Th (Type M) at agex, C-21 XI ------- C.17 C.I 8 D.I Gender-weighted average lifetime risk coefficients for ingestion of 232Th in food, using updated (ICRP, 1995a) and previous (ICRP, 1979) biokinetic models for thorium C-22 Gender-weighted average lifetime risk coefficients for inhalation of moderately soluble 232Th, using updated (ICRP, 1995a) and previous (ICRP, 1979) biokinetic models for thorium C-22 Comparison of gender-specific age-distributions in 1996 U.S. population with hypothetical stationary (ss, for steady-state) distributions based on 1989-91 U.S. life table D-2 xn ------- CHAPTER 1. INTRODUCTION Since the mid-1980s, a series of Federal guidance documents have been issued by the Environmental Protection Agency (EPA) for the purpose of providing Federal agencies with technical information to assist their implementation of radiation protection programs. Previous reports have dealt with numerical factors, called "dose factors" or "dose coefficients", for estimating radiation dose due to exposure to radionuclides. The present report is the first of a set of documents, referred to collectively as Federal Guidance Report No. 13, that will provide numerical factors, called "risk coefficients", for estimating risks to health from exposure to radionuclides. Report No. 13 will apply state-of-the-art methods and models that take into account age and gender dependence of intake, metabolism, dosimetry, radiogenic risk, and competing causes of death in estimating the risks to health from internal or external exposure to radionuclides. This initial volume (Part I) provides tabulations of risk coefficients for internal or external exposure to any of over 100 radionuclides through various environmental media. It is anticipated that Part II will address most remaining radionuclides of environmental significance. Subsequent parts may further expand the exposure pathways and health endpoints considered. The risk coefficients developed in this report apply to an average member of the public, in the sense that estimates of risk are averaged over the age and gender distributions of a hypothetical closed "stationary" population whose survival functions and cancer mortality rates are based on recent data for the U.S. Specifically, the total mortality rates in this population are defined by the 1989-91 U.S. decennial life table (NCHS, 1997) and cancer mortality rates are defined by U.S. cancer mortality data for the same period (NCHS, 1992, 1993a, 1993b). This hypothetical population is referred to as "stationary" because the gender-specific birth rates and survival functions are assumed to remain invariant over time. For a given radionuclide and exposure mode, both a "mortality risk coefficient" and a "morbidity risk coefficient" are provided. A mortality risk coefficient is an estimate of the risk to an average member of the U.S. population, per unit activity inhaled or ingested for internal exposures or per unit time-integrated activity concentration in air or soil for external exposures, of death from cancer as a result of intake of the radionuclide or external exposure to its emitted radiations. A morbidity risk coefficient is a comparable estimate of the average total risk of experiencing a radiogenic cancer, whether or not the cancer is fatal. The term "risk coefficient" with no modifier should be interpreted throughout this report as "mortality or morbidity risk coefficient". It is a common practice to estimate the cancer risk from internal or external exposure to a radionuclide as the simple product of a "probability coefficient" and an estimated "effective dose" ------- to a typical adult (see the Glossary for definitions). For example, a "nominal cancer fatality probability coefficient" of 0.05 Sv"1 is given in ICRP Publication 60 (1991) for all cancer types combined. This value is referred to as nominal because of the uncertainties inherent in radiation risk estimates and because it is based on an idealized population receiving a uniform dose over the whole body. It is pointed out by the ICRP (1991) that such a probability coefficient may be a less accurate estimator in situations where the distribution of dose is nonunifbrm. There are also other situations in which the product of a probability coefficient and the effective dose may not accurately represent the risk implied by current biokinetic, dosimetric, and radiation risk models. For example, such an estimate may understate the implied risk for intakes of radionuclides for which there is an apparently multiplicative effect during childhood of elevated organ doses and elevated risk per unit dose. Such an estimate may overstate the risk implied by current models in the case of intake of a long-lived, tenaciously retained radionuclide, because much of the dose may be received during late adulthood when there is a relatively high likelihood of dying from a competing cause before a radiogenic cancer can be expressed. Finally, the weighting factors commonly used to calculate effective dose do not reflect the most up-to-date knowledge of the distribution of risk among the organs and tissues of the body. In contrast to risk estimates based on the product of a nominal probability coefficient and effective dose (for intake by the adult), the risk coefficients tabulated in this document take into account the age dependence of the biological behavior and internal dosimetry of ingested or inhaled radionuclides. Also, compared with risk estimates based on effective dose, the risk coefficients in this document characterize more precisely the implications of age and gender dependence in radiogenic risk models, U.S. cancer mortality rates, and competing risks from non-radiogenic causes of death in the U.S. Finally, these risk coefficients take into account the age and gender dependence in the usage of contaminated environmental media, which is generally not considered in risk estimates based the simple product of a nominal probability coefficient and effective dose. Radionuclides and exposure scenarios addressed The radionuclides addressed are listed in Table 1.1. With the exceptions noted in the table, risk coefficients are provided for the following modes of exposure to a given radionuclide: inhalation of air, ingestion of food, ingestion of tap water, external exposure from submersion in air, external exposure from the ground surface, and external exposure from soil contaminated to an infinite depth. ------- Table 1.1. Radionuclides addressed in this report. H-3 C-14 S-35 Ar-37*, 39*. 41* Ca-45, 47 Sc-47 Fe-55, 59 Co-57, 58, 60 Ni-59, 63 Zn-65 Se-75, 79 Kr-74*, 76*, 77*, 79*, 81 m*. 81 *, 83m*, 85m*. 8,5*. 87*. 88* Br-74*, 76*. 77* Rb-87*, 88* Sr-89, 90 Y-90 Zr-95 Nb-94, 95m, 95 Mo-99 Tc-95m, 95, 99m, 99 Ru-103,106 Rh-103m*, 106* Ag-1 08m, 108*. 110m, 110* Sb-124, 125, 126, 127 Te-125m, 127m, 127, 129m, 129, 131m, 132 1-125, 129, 131, 132, 133, 134, 135 Xe-120*, 121*, 122*. 123*, 125*. 127*. 129m*. 131m*, 133m*, 133*; 135m*. 135", 138* Cs-134, 135, 136, 137, 138* Ba-133, 137m*, 140 La-140 Ce-141, 144 Pr-144m*, 144* TI-207*, 208*, 209* Pb-210, 211*, 212, 214* Bi-210, 211*, 212,214* Po-210, 211*, 212*, 214*. 215*. 216*, 218* Rn-218*. 219*, 220*. 222* Fr-223* Ra-223, 224, 226, 228 Ac-227, 228 Pa-231,233, 234m*, 234 Th-227, 228, 230, 231 , 232, 234 U-232, 233, 234, 235, 236, 238 Np-236a (T1/2, 1.15x105 y), 236b Pu-236, 238, 239, 240, 241 , 242 Am-241,243 Cm-242, 243, 244 , 22.5 h), 237, 239 *Risk coefficients are provided only for external exposure scenarios. ------- For internal exposure, attention has been restricted mainly to radionuclides addressed in the ICRP's series of documents on age-dependent doses to the public from intake of radionuclides (ICRP, 1989,1993,1995a, 1995b, 1996). However, risk coefficients for internal exposure are also provided for some additional isotopes of the elements considered in that series, as well as for radionuclides with half-lives of one hour or greater that occur in the decay chains of any of the radionuclides considered in the internal exposure scenarios. For external exposure, risk coefficients are provided for all radionuclides addressed in the internal exposure scenarios and all radionuclides of potential dosimetric importance occurring in the decay chains of those radionuclides (regardless of the radiological half-life), as well as for some important radioisotopes of noble gases and their decay chain members. For each of the internal exposure modes, the risk coefficient for a radionuclide includes the contribution to dose from production of decay chain members in the body after intake of the parent radionuclide, regardless of the half-lives of the decay chain members. For both internal and external exposure, a risk coefficient for a given radionuclide is based on the assumption that this is the only radionuclide present in the environmental medium; that is, doses due to decay chain members produced in the environment prior to intake of, or external exposure to, the radionuclide are not considered. However, a separate risk coefficient is provided for each decay chain member of potential dosimetric significance. This enables the user to assess the risks from ingrowth of radionuclides in the environment. The risk coefficients tabulated in this report are applicable to either chronic or acute exposure to a radionuclide. That is, a risk coefficient may be interpreted either as the average risk per unit exposure to members of a population exposed throughout life to a constant concentration of a radionuclide through an environmental medium, or as the average risk per unit exposure to members of a population acutely exposed to the radionuclide through the environmental medium. For purposes of computing the risk coefficients, it was assumed that the concentration of the radionuclide in the environmental medium remains constant and that all persons in the population are exposed to that environmental medium throughout their lifetimes. Applicability to the current U.S. population The risk coefficients are based on exposure of a hypothetical stationary population with survival functions and cancer mortality rates similar to those of the current U.S. population, but with steady-state gender and age distributions based on these survival functions and fixed gender-specific birth rates. Due to uncertainty in the future composition of the U.S. population, the use of such a ------- stationary population is appropriate for consideration of long-term, chronic exposures. Because the gender-specific age distributions in the current U.S. population differ considerably from those of the hypothetical stationary population, however, the question arises as to the applicability of these risk coefficients to short-term exposures of the U.S. population that might occur in the near future. This question is addressed in Appendix D, where the tabulated risk coefficients are compared with values calculated for short-term exposure of a hypothetical population with the age and gender distributions of the 1996 U.S. population. As is the case for the hypothetical stationary population, total mortality rates in the hypothetical 1996 population during and after exposure are assumed to be those given in the 1989-91 U.S. decennial life table, and cancer mortality rates are taken to be those given by U.S. cancer mortality data for the same period. The comparison reveals only small differences in risk coefficients for the two populations. Computation of the risk coefficients for internal exposure A schematic of the method of computation of a risk coefficient is shown in Fig. 1.1 for the case of internal exposure to a radionuclide. The main steps in the computation are shown in the numbered boxes in the figure and are summarized below. 1. Lifetime risk per unit absorbed dose at each age For each of 14 cancer sites in the body, radiation risk models are used to calculate gender-specific values for the lifetime risk per unit absorbed dose received at each age. The age- and gender-specific radiation risk models are described in Chapter 7. These models are taken from a recent EPA report (EPA, 1994) that provides a methodology for calculation of radiogenic cancer risks based on a critical review of data on the Japanese f Cancer risk coefficients \ f from epidemiologic studies; 1 V e.g., A-bomb survivors J Risk model coefficients transported to U.S. population 1. Lifetime, risk per unit absorbed dose at each age f U.S. age- and gender- I specific usage data for V environmental medium T_ U.S. vital statistics A and cancer mortality data J 3. Lifetime risk per unit activity intake at each age 4. Lifetime cancer risk for a constant activity concentration in environmental medium 5. Risk coefficient: Average lifetime cancer risk per unit activity intake C&ge-specific biokinetic md dosimetric methods 2. Absorbed dose rate as a function of time following a unit activity intake at each age Fig. 1.1. Components of the computation of risk coefficients. (The numbers identify the key steps described in the text.) ------- atomic bomb survivors and other study groups and methods of transporting radiation risk estimates across populations. Parameter values given in that EPA report have been modified in some cases to reflect updated vital statistics and cancer mortality data for the U.S. and to achieve greater consistency in the assumptions made in this report for different age groups and genders. The cancer sites considered are esophagus, stomach, colon, liver, lung, bone, skin, breast, ovary, bladder, kidney, thyroid, red marrow (leukemia), and residual (all remaining cancer sites combined). An absolute risk model is applied to bone, skin, and thyroid; that is, it is assumed for these sites that the radiogenic cancer risk is independent of the baseline cancer mortality rate, that is, the cancer mortality rate for that site in an unexposed population. For the other cancer sites, a relative risk model is used; that is, it is assumed that the likelihood of a radiogenic cancer is proportional to its baseline cancer mortality rate. The baseline cancer mortality rates are calculated from U.S. cancer mortality data for 1989-91 (NCHS, 1992,1993a, 1993b). The computation of gender- and cancer site-specific values for the lifetime risk per unit absorbed dose involves an integration over age, beginning at the age at which the dose is received, of the product of the age-specific risk model coefficient (times the baseline mortality rate of the cancer hi the case of a relative risk model) and the survival function. The survival function is used to account for the possibility that the exposed person may die from a competing cause before a radiogenic cancer is expressed. The computation is described in detail in Chapter 7. The estimates of lifetime risk per unit absorbed dose are independent of the radionuclide and exposure pathway. They are calculated only once and are used as input for the calculation of each risk coefficient. 2. Absorbed dose rates as a function of time post acute intake at each age Age-specific biokinetic models are used to calculate the time-dependent inventories of activity hi various regions of the body following acute intake of a unit activity of the radionuclide. For a given radionuclide and intake mode, this calculation is performed for each of six "basic" ages at intake: infancy (100 days); 1, 5,10, and 15 years; and maturity (usually 20 years, but 25 years in the biokinetic models for some elements). The biokinetic models used in this document are described in Chapter 4. With a few exceptions described in that chapter, the systemic biokinetic models and gastrointestinal uptake fractions are taken from the ICRP's recent series of documents on age-specific doses to members of the public from intake of radionuclides (ICRP, 1989, 1993, 1995a, 1995b, 1996). The respiratory tract model is taken from Publication 66 of the ICRP (1994a), ------- and the model for transit of material through the gastrointestinal tract is taken from Publication 30 of the ICRP (Part 1,1979). Age-specific dosimetric models are used to convert the calculated time-dependent regional activities in the body to absorbed dose rates (per unit intake) to radiosensitive tissues as a function of age at intake and time after intake. Absorbed dose rates for intake ages intermediate to the six basic ages at intake (infancy; 1,5,10, and 15 years; and maturity) are determined by interpolation. The dosimetric models used in this document are the models used in the ICRP's series of documents on age-specific doses to members of the public from intake of radionuclides (ICRP, 1989, 1993, 1995a, 1995b, 1996). These models are described in Chapter 5. 3. Lifetime cancer risk per unit intake at each age For each cancer site, the gender-specific values of lifetime risk per unit absorbed dose received at each age (derived in the first step) are used to convert the calculated absorbed dose rates to lifetime cancer risks, for the case of acute intake of one unit of activity at each age xf. This calculation involves integration over age of the product of the absorbed dose rate at age x for a unit intake at age xh the lifetime risk per unit absorbed dose received at age x, and the value of the survival function at age x divided by the value at age xt. The survival function is used to account for the probability that a person exposed at age xf is still alive at age jc to receive the absorbed dose. It is assumed that the radiation dose is sufficiently low that the survival function is not significantly affected by the number of radiogenic cancer deaths at any age. The calculation is described in Chapter 7. 4. Lifetime cancer risk for chronic intake As indicated earlier, the risk coefficients in this document are applicable to either chronic or acute exposures. However, for purposes of computing a risk coefficient, it is assumed that the concentration of the radionuclide in the environmental medium remains constant and that all persons in the population are exposed to that environmental medium throughout their lifetimes. The usage of environmental media may vary considerably with age and gender, and such variation is taken into account in the calculation of risk coefficients for the internal exposure scenarios. The age- and gender-specific models of usage of environmental media (air, food, or tap water) are described in Chapter 3. It is assumed that daily ingestion of a given radionuclide in food is proportional to age- and gender-specific daily energy intake. For radioisotopes of iodine, alternate ------- risk coefficients are calculated for food under the assumption that daily ingestion is proportional to age- and gender-specific daily usage of cow's milk. The age- and gender-specific ventilation rates applied here are reference values given by the ICRP, and age- and gender-specific usage rates for tap water, food energy, and cow's milk are average values estimated from recent data for the U.S. For each cancer site and each gender, the lifetime cancer risk for chronic exposure is obtained by integration over age x of the product of the lifetime cancer risk per unit intake at age x and the expected intake of the environmental medium at age x. The expected intake at a given age is the product of the usage rate of the medium and the value of the survival function at that age. 5. Average lifetime cancer risk per unit activity intake Because a risk coefficient is an expression of the radiogenic cancer risk per unit activity intake, the calculated lifetime cancer risk from chronic intake of the environmental medium must be divided by the expected lifetime intake. The expected lifetime intake is given by the integral over age of the product of the usage rate and the survival function. Therefore, in the calculation of a gender- and cancer site-specific risk coefficient, usage of the environmental medium appears both in the numerator (see Step 4) and the denominator. This makes the risk coefficient Independent of the concentration of the radionuclide in the medium and of the population-averaged usage rate of the medium but does not diminish the importance of the usage rate in the derivation of a risk coefficient. For example, the risk coefficient for a given radionuclide in food may differ considerably from the coefficient for the same radionuclide in tap water because the assumed age-specific patterns of consumption are substantially different for food and tap water. Except for the calculations of the time-dependent organ activities and absorbed dose rates, each of the steps described above is performed separately for each gender and each cancer site. A total risk coefficient is derived by first adding the risk estimates for the different cancer sites in each gender and then calculating a weighted mean of the coefficients for males and females. The weighted mean of coefficients for males and females involves the presumed gender ratio at birth, the gender-specific risk per unit intake at each age, and the gender-specific survival function at each age. Computation of the risk coefficients for external exposure The computation of risk coefficients for external exposure scenarios is similar to that for internal exposure scenarios but involves fewer steps because the absorbed dose rates are taken 8 ------- directly from Federal Guidance Report No. 12 (EPA, 1993). The methods and models used in that report are summarized in Chapter 6. As in the internal exposure scenarios, it is assumed that the concentration of the radionuclide in the environmental medium remains constant and that all persons in the population are exposed to that environmental medium throughout their lifetimes. The external dose rates used in the calculation were based on a reference adult male, standing outside with no shielding (EPA, 1993). Although there is expected to be some variation with age in organ dose rates from uniform external exposure (usually less than 30%), comprehensive tabulations of age-specific organ dose rates due to external exposure are not yet available. In the present document, the dose rates calculated for the adult male are applied to all ages and both genders, and no adjustments are made to account for potential reduction in dose rates due to shielding by buildings during time spent indoors. How to apply a risk coefficient The risk coefficients in this report may be used to assess per capita (population-averaged) risk due to the acute exposure of a population or, equivalently, to assess the risk due to the chronic lifetime exposure of an average individual to a constant environmental concentration. They also may be used to assess the per capita lifetime risk in a population from a lifetime exposure to a time varying environmental radionuclide exposure (or intake) rate, using the product of the risk coefficient and the lifetime exposure (or intake) due to that time varying rate. A risk coefficient, r, is specific to the radionuclide, the environmental medium, and the mode of exposure through that medium. For a given exposure scenario, the computation of lifetime cancer risk, R, associated with intake of, or external exposure to, a given radionuclide involves multiplication of the applicable risk coefficient r by the per capita activity intake / or external exposure X. Thus, R = r I for intake by inhalation or ingestion and R = r X for external exposure, where X denotes the time-integrated activity concentration of the radionuclide in air, on the ground surface, or within the soil, and /is the activity inhaled or ingested per capita. For external exposure, estimation of the time-integrated activity concentration ^"requires infbrmation on the (constant or time-dependent) concentration of the radionuclide hi the medium and the length of the exposure period. For an internal exposure scenario, estimation of the per capita activity intake /of the radionuclide requires the same information, plus an estimate of the average usage rate of the medium by members of the population during the exposure period. The user may apply the per capita usage rate of air, food, or tap water given in Chapter 3 (see the "combined lifetime average" usage rates in Table 3.1) or, because the risk coefficients are independent of the ------- usage rate of the medium, may apply an average usage rate better suited to the exposure scenario. For example, if the exposure scenario involves acute inhalation of a radionuclide in a rapidly passing cloud, the average inhalation rate hi the exposed population during the exposure period may differ from the 24-h average rate given in Chapter 3. However, the assumptions described in Chapter 3 concerning relative age- and gender-specific usage of the environmental media are inherent in the risk coefficients for internal exposure and hence cannot be changed by the user. Appendix E provides sample calculations that illustrate how the tabulated risk coefficients may be applied to different types of exposure. Limitations on use of the risk coefficients Analyses involving the risk coefficients tabulated in this report should be limited to estimation of prospective risks hi hypothetical or large existing populations, or retrospective analyses of risks to large actual populations. The tabulations are not intended for application to specific individuals and should not be used for that purpose. In contrast to situations involving representative population samples, the coefficients tabulated hi this report may not be appropriate for assessing the risk to an average individual in an age-specific cohort due to chronic exposure to an environmental concentration that varies substantially over the life of the cohort. In such special cases, the time-varying environmental concentration must be incorporated explicitly into the calculations described in Chapter 7. Such applications are beyond the scope of this report. The risk coefficients are based on radiation risk models developed for application either to low doses, defined as acute absorbed doses less than 0.2 Gy, or to low dose rates, defined as dose rates less than 0.1 mGy min'1 (EPA, 1994). Finally, the assumption is made that the absorbed dose is sufficiently low that the survival function is not significantly affected by the number of radiogenic cancer deaths at any age. Thus, these risk coefficients should be applied with care to cases involving large cumulative risks, either hi prospective or retrospective analyses. Uncertainties in the biokinetic, dosimetric, and radiation risk models The sources and extent of uncertainties hi the biokinetic, dosimetric, and radiation risk models used to derive the risk coefficients are discussed in the relevant sections of this report. The discussions of uncertainty are generally qualitative or semi-quantitative in nature and are consistent with recent assessments by experts hi the various fields. Because there is not full consensus of 10 ------- opinion among scientists regarding the reliability of estimates of lifetime cancer risk from low-level exposure to radiation, and because the error in such estimates may vary substantially from one radionuclide to another and one exposure scenario to another, no attempt is made here to characterize the overall uncertainty associated with any given risk coefficient. Software used to compute the risk coefficients All computations of dose and risk were performed using the DCAL (DOSE CALCULATION) software (Eckerman et al., to be published). DCAL is a comprehensive biokinetics-dose-risk computational system designed to serve current needs in radiation dosimetry and risk analysis. It performs biokinetic and dosimetric calculations for acute intake of a radionuclide by inhalation, ingestion, or injection into blood at a user-specified age. DCAL couples the generated absorbed dose rates with radiation risk estimators and mortality data to predict organ-specific risk of radiogenic cancer mortality or morbidity from intake of a radionuclide. DCAL has been extensively tested and has been compared with several widely used solvers for biokinetic models and systems of differential equations. DCAL was used by a task group of the ICRP to derive or check the dose coefficients given in its series of documents on age-specific doses to members of the public from intake of radionuclides (ICRP, 1989, 1993, 1995a, 1995b, 1996). Organization of the report Risk coefficients for cancer mortality and morbidity due to exposure to the radionuclides listed in Table 1.1 are tabulated in Chapter 2. To facilitate comparisons as well as conversion to other units, values typically are tabulated to three decimal places. No indication of uncertainty is intended or should be inferred from this practice. The assumptions and models used to derive the risk coefficients tabulated in Chapter 2 are described in Chapters 3 through 7. The exposure scenarios, including assumptions concerning the vital statistics of the exposed population and the age- and gender-specific usage rates of environmental media by the population, are described in Chapter 3. Biokinetic models, dosimetric models for internal exposure, dosimetric models for external exposure, and radiation risk models are described in Chapters 4, 5, 6, and 7, respectively. The sources and extent of uncertainties in the biokinetic, dosimetric, and radiation risk models are discussed in the chapters in which the respective models are described. 11 ------- Some additional details concerning the models used in the calculations are given in Appendices A and B. Appendix C provides a detailed illustration of the models and computational steps involved in the derivation of a risk coefficient for ingestion or inhalation of a radionuclide. In Appendix D, the tabulated risk coefficients are compared with values calculated for short-term exposure of a hypothetical population with age and gender distributions based on the 1996 U.S. population. Appendix E provides several sample calculations that illustrate how the tabulated risk coefficients may be applied to different types of exposure. A glossary of terms is provided at the end of the document. 12 ------- CHAPTER 2. TABULATIONS OF RISK COEFFICIENTS The risk coefficients tabulated here are based on a hypothetical stationary population with total mortality rates defined by the 1989-91 U.S. decennial life table (NCHS, 1997) and cancer mortality rates defined by U.S. cancer mortality data for the same period (NCHS, 1992, 1993a, 1993b). These coefficients may be interpreted in terms of either acute or chronic exposure to environmental radionuclides. That is, a risk coefficient may be interpreted as the risk per unit exposure of a typical person exposed throughout life to a constant concentration of a radionuclide in an environmental medium, or as the average risk per unit exposure to members of a stationary population that experiences an acute exposure to that radionuclide in that environmental medium. Risk coefficients are tabulated for the following modes of exposure: 1. inhalation of a radionuclide in air (Table 2.1); 2. ingestion of a radionuclide in tap water (Table 2.2); 3. ingestion of a radionuclide in food (Table 2.3a; an alternate set of risk coefficients for radioisotopes of iodine in food is given in Table 2.3b); 4. external exposure to radiation from a radionuclide in air (Table 2.4); 5. external exposure to radiation from a radionuclide on the ground surface (Table 2.4); 6. external exposure to radiation from a radionuclide in soil, assuming contamination to an infinite depth (Table 2.4). A risk coefficient for a given radionuclide is based on the assumption that this is the only radionuclide present in the environmental medium. In particular, ingrowth of chain members in the environmental medium is not considered. For each radionuclide addressed, however, a separate risk coefficient is provided for each subsequent member of the same chain that is of potential dosimetric significance. Risk coefficients for inhalation Risk coefficients for inhalation of radionuclides in air are given in Table 2.1. These coefficients are expressed as the risk of cancer mortality or morbidity per unit activity intake (Bq"1). For cases in which one cancer type contributes heavily to the total cancer mortality, Table 2.1 also lists the dominant cancer type and the percentage of the total cancer mortality represented by that 13 ------- cancer type. If no single cancer type represents more than 40% of the total cancer mortality, then none of the cancer types is considered to be dominant. The intake rate of a radionuclide in air is assumed to depend on age and gender. The age- and gender-specific inhalation rates used in this report are given in Chapter 3, Table 3.1. The form of the inhaled material is classified in terms of the rate of absorption from the lungs to blood, using the classification scheme of ICRP Publication 66 (ICRP, 1994a). Type F, Type M, and Type S represent fast, medium, and slow rates, respectively, of absorption of material inhaled in particulate form. Material-specific deposition and absorption models are used for vapors (Type V) and gases (Type G) (ICRP, 1995b). Although the ICRP recommends default absorption types of most of the radionuclides considered in this document, the information underlying the selection of an absorption type is often very limited and in many cases reflects occupational rather than environmental experience. Due to the uncertainties in the form of a radionuclide likely to be inhaled by members of the public, various plausible absorption types have been addressed in the derivation of a risk coefficient for inhalation of a radionuclide. The scheme for selection of plausible absorption types is described in Chapter 3. It is assumed that airborne radioactivity is in particulate form, except that: tritium is in the form of a vapor (HTO as Type V) or a gas (HT as Type G); carbon is in gaseous form (Type G) as carbon monoxide (CO) or carbon dioxide (CO2); iodine is in the form of a vapor (Type V), a gas (methyl iodide, CH3I, as Type G), or a particulate (Type F or Type M); and tellurium is in the form of a vapor (Type V) or a particulate (Type F, Type M, or Type S). Risk coefficients for inhalation of radionuclides in particulate form are based on an assumed activity median aerodynamic diameter (AMAD) of 1 jam. This particle size is recommended by the ICRP for consideration of environmental exposures in the absence of specific information about the physical characteristics of the aerosol (ICRP, 1994a). Risk coefficients for ingestion Ingestion of tap water Risk coefficients for ingestion of radionuclides in tap water are given in Table 2.2. These risk coefficients are expressed as the risk of cancer mortality or morbidity per unit activity intake (Bq"1). For cases hi which one cancer type contributes heavily to the total cancer mortality, Table 2.2 also lists the dominant cancer type and the percentage of the total cancer mortality represented 14 ------- by that cancer type. If no single cancer type represents more than 40% of the total cancer mortality, then none of the cancer types is considered to be dominant. The age- and gender-specific visage rates for tap water are given in Chapter 3, Table 3.1. Tap water usage is defined as water drunk directly as a beverage and water added to foods and beverages during preparation. It does not include water that is intrinsic in foods as purchased. Ingestion of food Risk coefficients for ingestion of radionuclides in food are given in Table 2.3a. These risk coefficients are expressed as the risk of cancer mortality or morbidity per unit activity intake (Bq"1), For eases in which one cancer type contributes heavily to the total cancer mortality, Table 2.3a also lists the dominant cancer type and the percentage of the total cancer mortality represented by that cancer type. If no single cancer type represents more than 40% of the total cancer mortality, then none of the cancer types is considered to be dominant. Food usage is defined as the total dietary intake, excluding tap water. The risk coefficients for food in Table 2.3a are based on the assumption that the intake rate of the radionuclide is proportional to food energy usage (kcal d"1). Age- and gender-specific values for daily usage of total food energy are given in Chapter 3, Table 3.1. The assessment of the intake of a radionuclide in food typically is based on its activity concentration in food (for example, Bq kg"1) and an average usage rate (kg d"1). The relation between food energy usage and food mass usage is discussed in Chapter 3. Table 2.3b gives a second set of risk coefficients for radioisotopes of iodine in food, based on the assumption that the intake of radioiodine is proportional to intake of cow's milk. Age- and gender-specific values for the assumed daily intake of cow's milk are given in Chapter 3, Table 3.L Risk coefficients for external exposure Risk coefficients are provided in Table 2.4 for each of three external exposure scenarios: external exposure from submersion in contaminated air, external exposure from contamination on the ground surface, and external exposure from soil contaminated to an infinite depth. A risk coefficient for a given radionuclide is expressed as the probability of radiogenic cancer mortality or morbidity per unit time integrated activity concentration in air, on the ground surface, or in soil. The coefficients for submersion in air are given in units of m3 Bq"1 s"1, those for exposure to radiation from the ground surface are given in units of m2 Bq"1 s"1, and those for exposure to radiation from 15 ------- soil contaminated to an infinite depth are given in units of kg Bq"1 s"1. Because the distribution of absorbed dose within the body is fairly uniform for most external exposures, the cancer type with the highest contribution to the total risk is not shown in Table 2.4. The risk coefficients in Table 2.4 are based on external dose rates tabulated in Federal Guidance Report No. 12 (EPA, 1993). Those dose rates were calculated for a reference adult male, standing outdoors with no shielding. Activity distributions in air, on the ground surface, or in soil were assumed to be of an infinite extent. In this report, no adjustments are made to account for potential differences with age and gender in the external doses received, potential reduction in dose due to shielding by buildings during time spent indoors, or the finite nature of the activity distribution in the environment. Adjustments for current age and gender distributions in the U.S. The risk coefficients tabulated in this chapter were developed for a stationary population with gender and age distributions that would eventually occur in a closed population with male-to-female birth ratios indicated by recent U.S. data and with time-invariant survival functions defined by the 1989-91 U.S. decennial life tables. Due to the uncertainty in the future composition of the U.S. population, the use of a stationary population based on recent U.S. vital statistics is judged to be appropriate for consideration of long-term, chronic exposures to the U.S. population. Because the gender-specific age distributions hi the current U.S. population differ considerably from those of the hypothetical stationary population, however, the question arises as to the applicability of these risk coefficients to short-term exposures of the U.S. population that might occur in the near future. In Appendix D, risk coefficients for the stationary population are compared with coefficients derived for short-term exposure of a population with gender and age distributions based on the 1996 U.S. population, but with the same survival functions and cancer mortality rates as the stationary population. The comparisons show that the risk coefficients for the stationary population are reasonably good approximations of the corresponding risk coefficients for short-term exposure of the 1996 U.S. population and that, for a given exposure scenario, the ratio of risk coefficients for the two populations varies little from one radionuclide to another. Scaling factors are provided in Appendix D for conversion of risk coefficients for the stationary population to more precise risk coefficients for a hypothetical short-term exposure to the 1996 U.S. population. 16 ------- Table 2.1. Mortality and morbidity risk coefficients for inhalation. Explanation of Entries Risk coefficients for inhalation of radionuclides are expressed as the probability of radiogenic cancer mortality or morbidity per unit intake, where the intake is averaged over all ages and both genders. The form of an inhaled radionuclide is classified in terms of the rate of absorption from the lungs to blood, using the classification scheme of ICRP Publication 66 (ICRP, 1994a). Type F, Type M, and Type S represent a fast rate, a medium rate, and a slow rate, respectively, of absorption of material inhaled in particulate form. It is assumed that airborne radioactivity is in particulate form, except that: tritium is in the form of a vapor (HTO as Type V) or a gas (HT as Type G); carbon is in gaseous form (Type G) as carbon monoxide (CO) or carbon dioxide (CO2); iodine is in the form of a vapor (Type V), a gas (methyl iodide, CH3I, as Type G), or a particulate (Type F or Type M); and tellurium is in the form of a vapor (Type V) or a particulate (Type F, Type M, or Type S). For all particulate matter, an activity median aerodynamic diameter (AMAD) of 1 urn is assumed. The/; values (gastrointestinal absorption fractions) shown are the values applied to the adult and may differ from the values applied to infants and children (see Table 4.1b). The cancer type that makes the largest contribution to cancer mortality resulting from intake of a radionuclide is given in the column labeled "dominant cancer type", and its percentage contribution to the total cancer mortality is given in the column labeled "% total mortality". For example, the entry for 47Ca in relatively soluble form (Type F) indicates that colon cancer would account for 53.9% of all cancer deaths attributable to this exposure. The entry "none" under "dominant cancer type" means that no single cancer type accounts for more than 40% of the total cancer mortality. To facilitate application of the risk coefficients, including conversion to other units, the coefficients are tabulated to three decimal places. No indication of uncertainty is intended or should be inferred from this practice. To express a risk coefficient in conventional units (nCi ), multiply by 3.7x10 Bq nCi"1. To express a risk coefficient in terms of a constant activity concentration in air (Bq m"3), multiply the coefficient by 2.75 *104 UA, where UA is the lifetime average inhalation rate (for example, 17.8 m3 d"1 in Table 3.1) and 2.75xl04 d is the average life span. Note that the relative age- and gender-specific inhalation rates indicated in Table 3.1 are inherent in the risk coefficient. 17 ------- Table 2.1. Mortality and morbidity risk coefficients for inhalation. AHAD Nuclide (pm) Type Hydrogen H-3 (HTO) H-3 (HT) Carbon C-14 (CO) C-14 (C02) Sulphur S-35 Calcium Ca-45 Ca-47 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 V G G G F M S F M S F M S 1 1 1 1 8 1 1 3 1 1 3 1 1 Mortality f, (Bq'1) .OE+00 .OE+00 .OE+00 .OE+00 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 1 1 6 3 3 1 1 2 2 3 3 1 1 .04E-12 .04E-14 .14E-14 .68E-13 .93E-12 .25E-10 .63E-10 .68E-11 .35E-10 .22E-10 .44E-11 .73E-10 .96E-10 Morbidity (Bq-1) 1 1 9 5 6 1 1 3 2 3 5 2 2 .52E-12 .52E-14 .09E-14 .39E-13 .28E-12 .36E-10 .77E-10 .23E-11 .54E-10 .47E-10 .37E-11 .13E-10 .40E-10 Dominant cancer % total type mortality none none none none colon lung lung 1 eukemi a lung lung colon lung lung - - - 43 95 96 71 93 96 53 74 75 .8 .1 .0 .5 .0 .5 .9 .4 .7 Scandium Sc-47 Iron Fe-55 Fe-59 Cobalt Co -57 Co-58 Co -60 Nickel Ni-59 Ni-63 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 M S F H S F M S F M S F M S F M S F M S F H S 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 5 1 5 5 1 .OE-04 .OE-04 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 6 6 3 1 1 1 3 3 1 4 8 3 1 1 3 8 2 1 9 3 2 3 9 .09E-11 .74E-11 .30E-11 .81E-11 .59E-11 .53E-10 .08E-10 .48E-10 .25E-11 .75E-11 .74E-11 .12E-11 .34E-10 .81E-10 .16E-10 .02E-10 .32E-09 .05E-11 .73E-12 .16E-11 .52E-11 .67E-11 .34E-11 7 8 4 2 1 2 3 3 1 5 1 4 1 2 4 9 2 1 1 3 3 .51E-11 .25E-11 .OOE-11 .16E-11 .75E-11 .15E-10 .60E-10 .97E-10 .88E-11 .65E-11 .01E-10 .70E-11 .62E-10 .15E-10 .62E-10 .68E-10 .72E-09 .55E-11 .26E-11 .43E-11 .72E-11 4.43E-11 1 .01E-10 lung lung leukemia leukemia lung none lung lung none lung lung none lung lung none lung lung none lung lung none lung lung 75 77 53 41 88 - 76 84 - 74 80 - 70 73 - 67 73 - 56 95 - 71 96 .3 .0 .6 .7 .5 .3 .7 .0 .0 .1 .4 .8 .8 .0 .2 .9 .1 18 ------- Table 2.1, continued AMAD Nuclide (/M) Zinc Zn-65 1.00 1.00 1.00 Selenium Se-75 1.00 1.00 Se-79 1.00 1.00 Strontium Sr-89 1.00 1.00 1.00 Sr-90 1.00 1.00 1.00 Yttrium Y-90 1.00 1.00 1.00 Zirconium Zr-95 1.00 1.00 1.00 Niobium Nb-94 1.00 1.00 1.00 Nb-95m 1.00 1.00 1.00 Nb-95 1.00 1.00 1.00 Molybdenum Mo-99 1.00 1.00 1.00 Technetium Tc-95m 1.00 1.00 1.00 Tc-95 1.00 1.00 1.00 Type f. F 5.0E-01 M l.OE-01 S l.OE-02 F 8.0E-01 M l.OE-01 F 8.0E-01 M l.OE-01 F 3.0E-01 M l.OE-01 S l.OE-02 F 3.0E-01 M l.OE-01 S l.OE-02 F l.OE-04 M l.OE-04 S l.OE-04 F 2.0E-03 M 2.0E-03 S 2.0E-03 F l.OE-02 M l.OE-02 S l.OE-02 F l.OE-02 M l.OE-02 S l.OE-02 F l.OE-02 M l.OE-02 S l.OE-02 F 8.0E-01 M l.OE-01 S l.OE-02 F 8.0E-01 M l.OE-01 S l.OE-02 F 8.0E-01 M l.OE-01 S l.OE-02 Mortality (Bq-1) 1.41E-10 1.20E-10 1.66E-10 7.18E-11 8.90E-11 6.30E-11 2.25E-10 7.60E-11 5.52E-10 7.22E-10 1.08E-09 2.65E-09 1.08E-08 5.77E-11 1.48E-10 1.60E-10 1.33E-10 3.92E-10 5.06E-10 3.89E-10 8.66E-10 3.20E-09 1.47E-11 7.23E-11 8.13E-11 3.89E-11 1.26E-10 1.51E-10 1.44E-11 8.75E-11 9.80E-11 1.35E-11 7.51E-11 1.03E-10 2.97E-12 4.66E-12 4.91E-12 Dominant Morbidity cancer % total (Bq"1) type mortality 2.05E-10 1.57E-10 2.02E-10 1.02E-10 1.09E-10 8.99E-11 2.50E-10 1.08E-10 6.32E-10 8.17E-10 1.17E-09 2.84E-09 1.15E-08 9.65E-11 2.13E-10 2.27E-10 1.77E-10 4.47E-10 5.70E-10 5.42E-10 1.02E-09 3.64E-09 2.31E-11 8.84E-11 9.84E-11 5.54E-11 1.48E-10 1.74E-10 2.15E-11 1.16E-10 1.30E-10 2.16E-11 9.20E-11 1.24E-10 5:01E-12 7.10E-12 7.43E-12 none lung lung none lung none lung colon lung lung 1 eukemi a lung lung colon colon lung none lung lung none lung lung colon lung lung none lung lung none lung lung colon lung lung none colon colon _ 46.1 65.0 _ 62.7 88.2 42.6 86.0 89.5 88.6 80.5 98.6 79.1 49.7 51.1 _ 81.0 86.2 _ 72.0 80.7 57.6 75.9 78.1 78.0 81.7 _ 63.0 63.3 40.8 66.9 69.8 _ 46.4 48.1 19 ------- Table 2.1, continued Nuclide AMAD (/mi) Type Mortality f, (Bq'1) Morbidity (Bq-1) Dominant cancer % total type mortality Technetium, continued Tc-99m Tc-99 1.00 1.00 1.00 1.00 1.00 1.00 F M s F M s 8 1 1 8 1 1 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 3 1 1 1 3 9 .62E-13 .20E-12 .29E-12 .86E-11 .49E-10 .67E-10 6 1 1 3 3 1 .90E-13 .54E-12 .64E-12 .14E-11 .81E-10 .03E-09 none lung lung colon lung lung - 65 66 52 94 98 .1 .4 .0 .9 .3 Ruthenium Ru-103 Ru-106 Silver Ag-108m Ag-llOm 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 F M S F M S F M S F M S 5 5 1 5 5 1 5 5 1 5 5 1 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 3 2 2 6 2 5 4 5 2 3 6 1 .28E-11 .12E-10 .59E-10 .13E-10 .42E-09 .56E-09 .09E-10 .82E-10 .42E-09 .90E-10 .22E-10 .03E-09 5 2 2 9 2 6 5 7 2 5 7 1 .12E-11 .41E-10 .90E-10 .41E-10 .77E-09 .02E-09 .68E-10 .21E-10 .82E-09 .47E-10 .65E-10 .22E-09 colon lung lung none lung lung none lung lung none lung lung 40 86 88 - 85 95 - 56 74 - 60 72 .2 .4 .7 .9 .6 .5 .3 .9 .0 Antimony Sb-124 Sb-125 Sb-126 Sb-127 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 F M S F M S F M S F M S 1 1 1 1 1 1 1 1 1 1 1 1 .OE-01 .OE-02 .OE-02 .OE-01 .OE-02 .OE-02 .OE-01 .OE-02 .OE-02 .OE-01 .OE-02 .OE-02 8 5 7 7 3 9 5 2 2 3 1 1 .55E-11 .65E-10 .54E-10 .52E-11 .99E-10 .74E-10 .90E-11 .51E-10 .85E-10 .50E-11 .60E-10 .77E-10 1 6 8 1 4 1 9 3 3 5 2 2 .30E-10 .58E-10 .65E-10 .04E-10 .49E-10 .08E-09 .26E-11 .10E-10 .49E-10 .83E-11 .03E-10 .23E-10 colon lung lung none lung lung colon lung lung colon lung lung 45 81 84 - 84 88 50 70 73 72 69 72 .4 .1 .3 .7 .6 .7 .5 .1 .0 .8 .0 Tellurium Te-125m Te-127m 1.00 1.00 1.00 1.00 1.00 1.00 V F M S V F M S 3 3 1 1 3 3 1 1 .OE-01 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-01 .OE-02 6 2 2 3 2 8 6 8 .89E-11 .54E-11 .88E-10 .61E-10 .43E-10 .65E-11 .34E-10 .60E-10 1 3 .02E-10 .87E-11 3.16E-10 3 3 1 6 9 .92E-10 .28E-10 .20E-10 .97E-10 .34E-10 leukemia leukemia lung lung 1 eukemi a 1 eukemi a lung lung 50 45 93 95 70 .9 .5 .4 .3 .1 64.9 91 95 .7 .6 20 ------- Table 2.1, continued Nuclide AMAD (/Jin) Type fi Mortality (Bq'1) Morbidity (Bq'1) Dominant cancer % total type mortality Tellurium, continued Te-127 Te-129m Te-129 Te-131m Te-132 Iodine 1-125 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 V F M S V F M S V F M S V F M S V F M S V (CH3I)G 1-129 1.00 1.00 F M V (CH3I)G 1-131 1.00 1.00 F M V (CH3I)G 1-132 1.00 1.00 F M V (CH3I)G 1-133 1.00 1.00 F M V (CH3I)G 1-134 1.00 1.00 F M V (CH3I)G 1.00 1.00 F M 3 3 1 1 3 3 1 1 3 3 1 1 3 3 1 1 3 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 .OE-01 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-01 .OE-02 .OE+00 .OE+00 .OE+00 .OE-01 .OE+00 .OE+00 .OE+00 .OE-01 .OE+00 .OE+00 .OE+00 .OE-01 .OE+00 .OE+00 .OE+00 .OE-01 .OE+00 .OE+00 .OE+00 .OE-01 .OE+00 .OE+00 .OE+00 .OE-01 6. 2. 1. 1. 2. 9. 5. 7. 2. 7. 2. 2. 5. 2. 7. 8. 1. 6. 1. 1. 7. 6. 2. 2. 4. 3. 1. 2. 1. 1. 5. 1. 1. 3. 2. 6. 5. 3. 1. 4. 7. 1. 1. 2. 01E-12 99E-12 24E-11 37E-11 29E-10 13E-11 83E-10 15E-10 52E-12 77E-13 26E-12 43E-12 52E-11 52E-11 77E-11 56E-11 40E-10 08E-11 74E-10 91E-10 75E-11 03E-11 97E-11 91E-11 42E-10 43E-10 68E-10 60E-10 48E-10 10E-10 55E-11 29E-10 12E-11 88E-12 46E-12 10E-12 46E-11 76E-11 93E-11 02E-11 41E-12 38E-12 15E-12 47E-12 9 5 1 1 3 1 6 8 3 1 2 2 2 9 1 1 5 2 2 2 7 5 2 8 4 3 1 7 1 1 5 2 3 2 1 8 4 3 1 7 1 5 2 3 .25E-12 .09E-12 .65E-11 .83E-11 .66E-10 .50E-10 .72E-10 .HE -10 .07E-12 .06E-12 .69E-12 .88E-12 .59E-10 .95E-11 .14E-10 .13E-10 .78E-10 .19E-10 .52E-10 .54E-10 .48E-10 .83E-10 .87E-10 .71E-11 .32E-09 .36E-09 .64E-09 .64E-10 .36E-09 .06E-09 .27E-10 .20E-10 .12E-11 .09E-11 .01E-11 .72E-12 .38E-10 .41E-10 .69E-10 .48E-11 .19E-11 .41E-12 .77E-12 .12E-12 colon colon lung lung leukemia leukemia lung lung lung none lung lung none colon lung lung none colon lung lung thyroid thyroid thyroid lung thyroid thyroid thyroid lung thyroid thyroid thyroid lung lung thyroid none lung thyroid thyroid thyroid lung lung none none lunq 46. 73. 62. 62. 48. 40. 86. 88. 67. - 67. 68. - 49. 61. 63. 46. 60. 62. 96. 96. 95. 63. 97. 97. 97. 74. 90. 95. 94. 76. 54. 44. - 51. 77. 88. 85. 46. 73. - 56. 0 1 0 0 7 3 0 9 5 2 3 1 5 1 4 4 1 0 1 9 4 3 8 7 9 8 0 0 8 8 9 0 2 5 2 7 7 8 21 ------- Table 2.1, continued Nuclide AMAD (//m) Type fi Mortality (Bq-1) Morbidity (Bq'1) Dominant cancer % total type mortality Iodine, continued 1-135 V (CH3I)G Cesium Cs-134 Cs-135 Cs-136 Cs-137 Barium Ba-133 Ba-140 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 F M F M F M F M F M F M S F M S 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 2 1 1 .OE+00 .OE+00 .OE+00 .OE-01 .OE+00 .OE-01 .OE+00 .OE-01 .OE+00 .OE-01 .OE+00 .OE-01 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 1. 1. 5. 1. 3. 7. 3. 2. 6. 2. 2. 7. 1. 2. 7. 1. 4. 5. 93E-11 01E-11 57E-12 47E-11 05E-10 05E-10 40E-11 58E-10 39E-11 12E-10 19E-10 81E-10 23E-10 67E-10 74E-10 02E-10 61E-10 30E-10 9 7 3 2 4 8 5 2 9 2 3 8 1 3 8 1 5 6 .85E-11 .42E-11 .63E-11 .38E-11 .45E-10 .36E-10 .03E-11 .82E-10 .44E-11 .54E-10 .21E-10 .91E-10 .69E-10 .14E-10 .78E-10 .70E-10 .48E-10 .20E-10 thyroid thyroid thyroid lung none lung none lung none lung none lung none lung lung colon lung lung 43. 67. 59. 47. 73. 93. - 76. - 83. - 70. 81. 74. 79. 82. 9 9 0 2 4 2 1 7 7 4 8 9 9 Lanthanum La -140 Cerium Ce-141 Ce-144 Lead Pb-210 Pb-212 Bismuth Bi-210 Bi-212 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 F M S F M S F M S F M S F M S F M S F H S 5 5 5 5 5 5 5 5 5 2 1 1 2 1 1 5 5 5 5 5 5 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 3. 8. 9. 4. 2. 3. 1. 2. 4. 1. 6. 4. 3. 1. 1. 5. 8. 1. 3. 1. 2. 67E-11 98E-11 61E-11 93E-11 76E-10 30E-10 95E-09 65E-09 49E-09 82E-08 84E-08 06E-07 84E-10 48E-08 64E-08 85E-11 10E-09 16E-08 75E-10 99E-09 17E-09 5 1 1 6 3 3 2 2 4 2 7 4 5 1 1 9 8 1 4 2 2 .83E-11 .29E-10 .37E-10 .41E-11 .07E-10 .64E-10 .26E-09 .96E-09 .87E-09 .47E-08 .48E-08 .28E-07 .43E-10 .56E-08 .73E-08 .92E-11 .56E-09 .23E-08 .10E-10 .10E-09 .29E-09 colon colon lung none lung lung none lung lung none lung lung none lung lung colon lung lung lung lung lung 60. 46. 47. - 89. 92. - 73. 95. - 87. 99. - 99. 99. 60. 99. 99. 92. 99. 99. 5 6 8 8 8 3 3 9 7 3 5 3 4 7 0 7 9 22 ------- Table 2.1, continued Nuclide AMAD (A/m) Type fi Mortality (Bq-1) Morbidity (Bq-1) Dominant cancer % total type mortality Polonium Po-210 Radium Ra-223 Ra-224 Ra-226 Ra-228 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 F M S F M S F M S F M S F M S 1 1 1 2 1 1 2 1 1 2 1 1 2 1 1 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 .OE-01 .OE-01 .OE-02 1 2 3 3 6 7 2 2 2 5 2 7 2 1 1 .97E-08 .76E-07 .71E-07 .91E-09 .42E-07 .50E-07 .60E-09 .56E-07 .90E-07 .90E-09 .93E-07 .23E-07 .34E-08 .26E-07 .12E-06 2 2 3 5 6 7 3 2 3 8 3 7 3 1 1 .69E-08 .93E-07 .91E-07 .40E-09 .76E-07 .90E-07 .61E-09 .70E-07 .06E-07 .31E-09 .09E-07 .61E-07 .28E-08 .40E-07 .18E-06 none lung lung none lung lung none lung lung none lung lung none lung lung 97. 99. 99. 99. - 99. 99. 99. 99. 82. 99. 8 9 8 9 7 8 2 9 7 4 Actinium Ac -227 Ac -228 1.00 1.00 1.00 1.00 1.00 1.00 F M S F M S 5 5 5 5 5 5 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 3 2 3 3 8 1 .32E-06 .35E-06 .88E-06 .41E-10 .56E-10 .33E-09 4 2 4 4 9 1 .17E-06 .72E-06 .HE -06 .09E-10 .22E-10 .41E-09 liver lung lung liver lung lung 43. 48. 96. 58. 85. 98. 3 5 9 5 9 9 Protactinium Pa -231 Pa -233 Pa-234 Thorium Th-227 Th-228 Th-230 Th-231 Th-232 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 F M S F M S F M S M S M S M S M S M S 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 2 1 1 5 2 3 7 2 3 7 9 2 3 5 7 2 3 5 1 .31E-06 .19E-06 .19E-06 .57E-11 .92E-10 .45E-10 .80E-12 .80E-11 .02E-11 .23E-07 .OOE-07 .03E-06 .40E-06 .28E-07 .23E-07 .95E-11 .23E-11 .18E-07 .10E-06 3 1 1 7 3 3 1 3 3 7 9 2 3 6 7 3 4 6 1 .18E-06 .53E-06 .29E-06 .32E-11 .28E-10 .84E-10 .25E-11 .67E-11 .94E-11 .62E-07 .48E-07 .18E-06 .58E-06 .36E-07 .70E-07 .78E-11 .10E-11 .45E-07 .17E-06 bone none lung leukemia lung lung colon lung lung lung lung lung lung lung lung lung lung lung lung 51. 91. 47. 88. 91. 61. 61. 62. 99. 100. 93. 99. 54. 96. 69. 70. 46. 97. 8 4 3 3 3 7 5 9 7 0 5 8 9 4 3 9 8 0 23 ------- Table 2.1, continued AHAD Mortality Nuclide (fm) Type f, (Bq'1) Morbidity (Bq'1) Dominant cancer type % total mortality Thorium, continued Th-234 1.00 1.00 Uranium U-232 1.00 1.00 1.00 U-233 1.00 1.00 1.00 U-234 1.00 1.00 1.00 U-235 1.00 1.00 1.00 U-236 1.00 1.00 1.00 U-238 1.00 1.00 1.00 Neptunium Np-236af1.00 1.00 1.00 Np-236b*1.00 1.00 1.00 Np-237 1.00 1.00 1.00 Np-239 1.00 1.00 1.00 Plutonium Pu-236 1.00 1.00 1.00 Pu-238 1.00 1.00 1.00 M 5.0E-04 S 5.0E-04 F 2.0E-02 M 2.0E-02 S 2.0E-03 F 2.0E-02 M 2.0E-02 S 2.0E-03 F 2.0E-02 M 2.0E-02 S 2.0E-03 F 2.0E-02 M 2.0E-02 S 2.0E-03 F 2.0E-02 M 2.0E-02 S 2.0E-03 F 2.0E-02 M 2.0E-02 S 2.0E-03 F 5.0E-04 M 5.0E-04 S 5.0E-04 F 5.0E-04 M 5.0E-04 S 5.0E-04 F 5.0E-04 M 5.0E-04 S 5.0E-04 F 5.0E-04 M 5.0E-04 S 5.0E-04 F 5.0E-04 M 5.0E-04 S l.OE-05 F 5.0E-04 M 5.0E-04 S l.OE-05 6.06E-10 7.11E-10 7.11E-08 4.86E-07 2.37E-06 1.23E-08 2.96E-07 7.27E-07 1.20E-08 2.90E-07 7.14E-07 1.12E-08 2.57E-07 6.42E-07 1.13E-08 2.68E-07 6.63E-07 1.09E-08 2.38E-07 6.07E-07 4.61E-08 1.97E-08 3.06E-08 7.71E-11 1.97E-10 3.28E-10 3.48E-07 4.18E-07 7.32E-07 1.48E-11 8.75E-11 9.66E-11 4.92E-07 5.60E-07 7.56E-07 1.19E-06 8.04E-07 9.06E-07 * Np-236 isomer with half-life of * Np-236 isomer with half-life of 7.16E-10 8.31E-10 9.96E-08 5.26E-07 2.50E-06 1.74E-08 3.13E-07 7.65E-07 1.70E-08 3.08E-07 7.51E-07 1.59E-08 2.73E-07 6.77E-07 1.61E-08 2.83E-07 6.98E-07 1.54E-08 2.52E-07 6.39E-07 6.33E-08 2.64E-08 3.30E-08 1.04E-10 2.18E-10 3.49E-10 4.72E-07 4.79E-07 7.75E-07 2.44E-11 1.08E-10 1.18E-10 5.91E-07 6.16E-07 7.99E-07 1.41E-06 9.07E-07 9.60E-07 l.lBxlO5 y. 22.5 h. lung lung none lung lung none lung lung none lung lung none lung lung none lung lung none lung lung bone bone lung none lung lung bone lung lung colon lung lung liver lung lung liver lung lung 80.0 84.7 - 92.3 99.5 - 98.6 99.9 - 98.6 99.9 - 98.5 99.9 - 98.6 99.9 - 98.4 99.9 46.6 42.5 92.3 - 84.6 97.9 44.4 70.3 98.1 70.5 75.2 76.7 59.5 69.1 97.9 62.6 46.4 95.0 24 ------- Table 2.1, continued Nuclide AMAD (//m) Type Mortality f, (Bq-1) Plutonium, continued Pu-239 Pu-240 Pu-241 Pu-242 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 F M s F M S F M S F M S 5.0E-04 5 1 5 5 1 5 5 1 5 5 1 .OE-04 .OE-05 .OE-04 .OE-04 .OE-05 .OE-04 .OE-04 .OE-05 .OE-04 .OE-04 .OE-05 1. 7. 8. 1. 7. 8. 1. 7. 3. 1. 7. 7. 26E-06 94E-07 45E-07 26E-06 95E-07 47E-07 98E-08 67E-09 51E-09 19E-06 46E-07 88E-07 Morbidity (Bq-1) 1, .49E-06 8.99E-07 8.96E-07 1.50E-06 9.00E-07 8.98E-07 2 9 3 1 8 8 .34E-08 .02E-09 .82E-09 .42E-06 .46E-07 .36E-07 Dominant cancer type liver lung lung liver lung lung liver liver lung liver lung lung % total mortality 62.9 42.4 94.2 62 42 94 65 64 73 62 41 94 .9 .4 .2 .2 .4 .7 .9 .7 .1 Americium Am- 241 Am -243 Curium Cm -242 Cm-243 Cm -244 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 F M S F M S F M S F M S F M S 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 7. 6. 9. 7. 6. 8. 5. 98E-07 59E-07 04E-07 88E-07 33E-07 58E-07 77E-08 3.84E-07 5.15E-07 6.50E-07 6.43E-07 9.38E-07 5.68E-07 6.10E-07 9.09E-07 1 7 9 1 7 9 6 4 5 8 7 9 7 6 9 .02E-06 .60E-07 .58E-07 .OOE-06 .31E-07 .HE -07 .80E-08 .07E-07 .42E-07 .18E-07 .27E-07 .93E-07 .HE -07 .84E-07 .61E-07 none lung lung none lung lung liver lung lung liver lung lung liver lung lung - 56 96 - 55 96 63 95 99 42 63 97 44 66 .3 .5 .0 .3 .5 .9 .9 .6 .5 .4 .4 .4 97.8 25 ------- ------- Table 2.2 Mortality and morbidity risk coefficients for ingestion of tap water. Explanation of Entries Risk coefficients for ingestion of radionuclides in tap water are expressed as the probability of radiogenic cancer mortality or morbidity per unit intake, where the intake is averaged over all ages and both genders. With two exceptions, the risk coefficient for ingestion of a radionuclide in tap water applies to all forms of the radionuclide. For 3H, separate risk coefficients are given for tritiated water (HTO) and organically bound tritium (OBT), for which different biokinetic models are recommended by the ICRP (1989). Similarly, for 35S, separate risk coefficients are given for inorganic sulfur and organically bound sulfur (I-S and OBS, respectively), for which different biokinetic models also are recommended (ICRP, 1993). The// values (gastrointestinal absorption fractions) shown are the values applied to the adult and may differ from the values applied to infants and children (see Table 4.la). The cancer type that makes the largest contribution to cancer mortality resulting from intake of a radionuclide is given in the column labeled "dominant cancer type", and its percentage contribution to the total cancer mortality is given in the column labeled "% total mortality". For example, the entry for ingestion of 47Ca indicates that colon cancer would account for 81.3% of all cancer deaths attributable to this exposure. The entry "none" under "dominant cancer type" means that no single cancer type accounts for more than 40% of the total cancer mortality. To facilitate application of the risk coefficients, including conversion to other units, the coefficients are tabulated to three decimal places. No indication of uncertainty is intended or should be inferred from this practice. To express a risk coefficient in conventional units (uCi"1), multiply by 3.7xl04 Bq lo.Ci"1. To express a risk coefficient hi terms of a constant activity concentration in tap water (Bq L"1), multiply the coefficient by 2.75xl04 Uw, where Uwis the lifetime average rate of ingestion of tap water (for example, 1.11 L d"1 in Table 3.1) and 2.75xl04 d is the average life span. Note that the relative age- and gender-specific ingestion rates of tap water indicated in Table 3.1 are inherent in the risk coefficient. 27 ------- Table 2.2. Mortality and morbidity risk coefficients for ingestion of tap water. Nuclide Hydrogen H-3(HTO) H-3COBT) Carbon C-14 Sulfur S-35(I-S) S-35COBS) Calcium Ca-45 Ca-47 Scandium Sc-47 Iron Fe-55 Fe-59 Cobalt Co -57 Co -58 Co -60 Nickel Ni-59 Ni-63 Zinc Zn-65 Selenium Se-75 Se-79 Strontium Sr-89 Sr-90 Yttrium Y-90 Zirconium Zr-95 Niobium Nb-94 Nb-95m Nb-95 Mortality fi (Bq'1) 1 1 1 1 1 3 3 1 1 1 1 1 1 .OE+00 .OE+00 .OE+00 .OE+00 .OE+00 .OE-01 .OE-01 .OE-04 .OE-01 .OE-01 .OE-01 .OE-01 .OE-01 5.0E-02 5.0E-02 5. OE-01 8. OE-01 8. OE-01 3. OE-01 3. OE-01 l.OE-04 l.OE-02 l.OE-02 l.OE-02 l.OE-02 9 2 2 8 4 4 1 5 1 1 .44E-13 .09E-12 .89E-11 .87E-12 .99E-11 .74E-11 .19E-10 .24E-11 .81E-11 .36E-10 1.70E-11 4.85E-11 2.75E-10 4.44E-12 1.08E-11 2.16E-10 1.56E-10 1.38E-10 2. 1. 2. 7. 1. 5. 3. 10E-10 34E-09 70E-10 09E-11 22E-10 49E-11 83E-11 Morbidity (Bq-1) 1 3 4 1 7 6 2 9 2 2 .37E-12 .03E-12 .20E-11 .39E-11 .36E-11 .68E-11 .04E-10 .44E-11 .33E-11 .13E-10 2.81E-11 7.97E-11 4.25E-10 7.41E-12 1.81E-11 3.15E-10 2.20E-10 1.97E-10 3.47E-10 1. 4. 1. 2. 9. 6. 51E-09 88E-10 24E-10 10E-10 88E-11 64E-11 Domi nant cancer % total type mortality none none none none none leukemia colon colon leukemia colon colon colon none colon colon none none none colon leukemia colon colon colon colon colon _ _ _ _ _ 47 81 97 46 50 62 60 _ .1 .3 .2 .8 .0 .2 .5 66.1 66.6 _ _ 75.2 82.5 98.3 85. 80. 97. 82. 8 6 2 7 Molybdenum Mo -99 1. OE+00 3. 12E-11 4. 33E-11 none _ Technetium Tc-95m Tc-95 5. 5. OE-01 OE-01 2. 9. 96E-11 24E-12 4. 1. 87E-11 56E-11 colon colon 56. 58. 3 6 28 ------- Table 2.2, continued Nuclide Technetium, Tc-99m Tc-99 5. 5. fi Mortality (Bq'1) Morbidity (Bq-1) Dominant cancer % total type mortality continued OE-01 OE-01 1. 4. 22E-12 28E-11 2.15E-12 7.44E-11 colon colon 63. 72. 5 2 Ruthenium Ru-103 Ru-106 Silver Ag-108m Ag-llOm Antimony Sb-124 Sb-125 Sb-126 Sb-127 Tellurium Te-125m Te-127m Te-127 Te-129m Te-129 Te-131m Te-132 Iodine 1-125 1-129 1-131 1-132 1-133 1-134 1-135 Cesium Cs-134 Cs-135 Cs-136 Cs-137 Barium Ba-133 Ba-140 5. 5. 5. 5. 1. 1. 1. 1. 3. 3. 3. 3. 3. 3. 3. 1. 1. 1. 1. 1. 1. OE-02 OE-02 OE-02 OE-02 OE-01 OE-01 OE-01 OE-01 OE-01 OE-01 OE-01 OE-01 OE-01 OE-01 OE-01 OE+00 OE+00 OE+00 OE+00 OE+00 OE+00 l.OE+00 l.OE+00 l.OE+00 l.OE+00 l.OE+00 2. OE-01 2. OE-01 5. 6. 1. 1. 2. 7. 1. 1. 5. 1. 1. 2. 3. 9. 1. 7. 88E-11 45E-10 42E-10 68E-10 OOE-10 27E-11 72E-10 52E-10 42E-11 51E-10 53E-11 39E-10 211-12 04E-11 94E-10 14E-11 4.07E-10 1.31E-10 6.87E-12 4.63E-11 3.68E-12 1.39E-11 7.91E-10 8.72E-11 1.60E-10 5.66E-10 1.27E-10 2.30E-10 1.04E-10 1. ,14E-09 2.20E-10 2.67E-10 3.48E-10 1, .18E-10 3. OOE-10 2.72E-10 8.99E-11 2.33E-10 2.71E-11 4.14E-10 4.62E-12 2.23E-10 4.60E-10 6 3 1 2 3 6 8 1 1 2 8 1 4 .87E-10 .99E-09 .23E-09 .28E-11 .90E-10 .76E-12 .24E-11 .14E-09 .28E-10 .34E-10 .22E-10 .84E-10 .03E-10 colon colon colon colon colon colon colon colon colon colon colon colon stomach colon colon thyroid thyroid thyroid none thyroid stomach thyroid none none none none none colon 87. 87. 49. 56. 85. 66. 83. 94. 64. 51. 90. 75. 52. 79. 78. 9 4 8 1 6 6 6 4 8 8 9 7 9 5 3 95.5 97.6 93.2 - 81.3 61.9 52.1 - - - - - 88 .2 Lanthanum La -140 Cerium Ce-141 Ce-144 Lead Pb-210 Pb-212 5.0E-04 5.0E-04 5.0E-04 2. OE-01 2. OE-01 1.67E-10 6 5 1 4 .93E-11 .27E-10 .75E-08 .23E-10 2 1 9 2 6 .96E-10 .25E-10 .52E-10 .38E-08 .76E-10 colon colon colon none colon 92 97 98 - 51 .3 .8 .3 .0 29 ------- Table 2.2, continued Nuclide Bismuth Bi-210 Bi-212 Polonium Po-210 Radium Ra-223 Ra-224 Ra-226 Ra-228 Actinium Ac -227 Ac -228 Mortality Morbidity fi (Bq-1) (Bq-1) 5 5 5 2 2 2 2 5 5 .OE-02 .OE-02 .OE-01 .OE-01 .OE-01 .OE-01 .OE-01 .OE-04 .OE-04 1 1 3 4 2 5 2 4 3 .34E-10 .35E-11 .53E-08 .OOE-09 .74E-09 .32E-09 .OOE-08 .43E-09 .13E-11 2 1 4 6 4 7 2 5 5 .41E-10 .92E-11 .79E-08 .44E-09 .50E-09 .75E-09 .81E-08 .43E-09 .41E-11 Dominant cancer % total type mortality colon stomach none colon colon none none liver colon 95 50 - 57 61 - - 56 85 .3 .8 .7 .2 .5 .8 Protactinium Pa -231 Pa-233 Pa-234 Thorium Th-227 Th-228 Th-230 Th-231 Th-232 Th-234 Uranium U-232 U-233 U-234 U-235 U-236 U-238 5 5 5 5 5 5 5 5 5 2 2 2 2 2 2 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 .OE-02 4 8 4 7 1 1 3 1 3 5 1 1 1 1 1 .77E-09 .34E-11 .OOE-11 .21E-10 .82E-09 .67E-09 .31E-11 .87E-09 .46E-10 .52E-09 .26E-09 .24E-09 .21E-09 .17E-09 .13E-09 6 1 6 1 2 2 5 2 6 7 1 1 1 1 1 .74E-09 .50E-10 .93E-11 .28E-09 .90E-09 .46E-09 .96E-11 .73E-09 .25E-10 .88E-09 .94E-09 .91E-09 .88E-09 .81E-09 .73E-09 bone colon colon colon colon none colon none colon none none none none none none 47 96 85 93 55 - 97 - 98 - - - - - .0 .9 .6 .2 .9 .2 .6 Neptunium Np-236af Np-236b* Np-237 Np-239 Plutonium Pu-236 Pu-238 Pu-239 Pu-240 Pu-241 Pu-242 5 5 5 5 5 5 5 5 5 5 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 .OE-04 1 1 1 7 1 2 2 2 3 2 .78E-10 .68E-11 .10E-09 .70E-11 .44E-09 .75E-09 .85E-09 .85E-09 .94E-11 .71E-09 2 3 1 1 2 3 3 3 4 3 .83E-10 .01E-11 .67E-09 .39E-10 .02E-09 .55E-09 .64E-09 .65E-09 .77E-11 .46E-09 colon colon colon colon liver liver liver liver liver liver 51 95 40 97 40 52 53 53 62 53 .8 .4 .4 .0 .2 .7 .9 .8 .0 .9 Americium Am-241 5 .OE-04 2 * Np-236 isomer with * Np-236 isomer with .01E-09 half -life half -life 2 .81E-09 of 1.15x10 none 5y. - of 22.5 h. 30 ------- Table 2.2, continued Nudide Mortality (Bq-1) Morbidity Dominant cancer * total type mortality Americium, continued Am-243 5.0E-04 2.00E-09 Curium 2.79E-09 none Cm- 242 Cm- 243 Cm- 244 5. 5. 5. OE-04 OE-04 OE-04 6 1 1 .15E-10 .81E-09 .59E-09 1 2 2 .04E-09 .56E-09 .26E-09 colon none none 80. 3 31 ------- ------- Table 2.3a. Mortality and morbidity risk coefficients for ingestion of food. Explanation of Entries The intake rate of a radionuclide in food (total diet, excluding tap water) is assumed to be proportional to the energy intake rate. Risk coefficients for ingestion of radionuclides in food are expressed as the probability of radiogenic cancer mortality or morbidity per unit intake, where the intake is averaged over all ages and both genders. With two exceptions, the risk coefficient for ingestion of a radionuclide in food applies to all forms of the radionuclide. For 3H, separate risk coefficients are given for tritiated water (HTO) and organically bound tritium (OBT), because different biokinetic models are used for the two forms. Similarly, for 35S, separate risk coefficients are given for inorganic sulfur (I-S) and organically bound sulfur (OBS) because different biokinetic models are applied to the two forms. The/} values (gastrointestinal absorption fractions) shown are the values applied to the adult and may differ from the values applied to infants and children (see Table 4.la). The cancer type that makes the largest contribution to cancer mortality resulting from intake of a radionuclide is given in the column labeled "dominant cancer type", and its percentage contribution to the total cancer mortality is given in the column labeled "% total mortality". For example, the entry for 47Ca indicates that colon cancer would account for 83.5% of all cancer deaths attributable to this exposure. The entry "none" under "dominant cancer type" means that no single cancer type accounts for more than 40% of the total cancer mortality. To facilitate application of the risk coefficients, including conversion to other units, the coefficients are tabulated to three decimal places. No indication of uncertainty is intended or should be inferred from this practice. To express a risk coefficient in conventional units (uCi"1), multiply by 3.7><104 Bq jaCi"1. To express a risk coefficient in terms of a constant activity concentration in food (Bq kg"1), multiply by 2.75 xlO4 Up, where UF is the lifetime average intake rate of food in terms of mass (for example, 1.2 kg d , suggested in Chapter 3), and 2.75><104d is the average life span. To express a risk coefficient in terms of activity per unit energy (Bq kcal"1), multiply by 2.75xl04 UE, where UE is the lifetime average intake rate of food energy (for example, 2048 kcal d" in Table 3.1). Note that the relative age- and gender-specific food intake rates indicated in Table 3.1 are inherent in the risk coefficient. 33 ------- Table 2.3a. Mortality and morbidity risk coefficients for ingestionoffood. Nuclide Hydrogen H-3CHTO) H-S(OBT) Carbon C-14 Sulfur S-35(I-S) S-35(OBS) Calcium Ca-45 Ca-47 Scandium Sc-47 Iron Fe-55 Fe-59 Cobalt Co -57 Co -58 Co -60 Nickel Ni-59 Ni-63 Zinc Zn-65 Selenium Se-75 Se-79 Strontium Sr-89 Sr-90 Yttrium Y-90 Zirconium Zr-95 Niobium Nb-94 Nb-95m Nb-95 1. 1. 1. 1. 1. 3. 3. 1. 1. 1. 1. 1. 1. 5. 5. 5. 8. 8. 3. 3. 1. 1. 1. 1. 1. f; OE+00 OE+00 OE+00 OE+00 OE+00 OE-01 OE-01 OE-04 OE-01 OE-01 OE-01 OE-01 OE-01 OE-02 OE-02 OE-01 OE-01 OE-01 OE-01 OE-01 OE-04 OE-02 OE-02 OE-02 OE-02 Mortality Morbidity (Bq-1) (Bq'1) 1 2 3 1 6 6 1 7 2 1 2 6 3 6 1 2 2 1 2 1 3 1 1 8 5 .20E-12 .66E-12 .68E-11 .21E-11 .72E-11 .27E-11 .69E-10 .67E-11 .39E-11 .91E-10 .43E-11 .82E-11 .88E-10 .26E-12 .53E-11 .82E-10 .04E-10 .82E-10 .97E-10 .62E-09 .96E-10 .01E-10 .73E-10 .03E-11 .43E-11 1 3 5 1 1 9 2 1 3 3 4 1 6 1 2 4 2 2 4 1 7 1 3 1 9 .76E-12 .89E-12 .40E-11 .90E-11 .OOE-10 .10E-11 .92E-10 .38E-10 .14E-11 .01E-10 .03E-11 .13E-10 .03E-10 .05E-11 .57E-11 .15E-10 .91E-10 .62E-10 .96E-10 .86E-09 .16E-10 .78E-10 .01E-10 .45E-10 .47E-11 Dominant cancer % total type mortality none none none none none colon colon colon leukemia colon colon colon none colon colon none none none colon leukemia colon colon colon colon colon - - 51 83 97 43 52 63 62 68 69 _ _ 78 79 98 87 82 97 84 .4 .5 .4 .6 .3 .6 .3 ,8 .3 .2 .5 .4 .7 .8 .5 .7 Molybdenum Ho-99 1. OE+00 4 .06E-11 5 .71E-11 none Technetium Tc-95m Tc-95 5. 5. OE-01 OE-01 4 1 .09E-11 .28E-11 6 2 .79E-11 .17E-11 colon colon 59 61 .1 ,4 34 ------- Table 2.3a, continued Nuclide Technetium Tc-99m Tc-99 5 5 fi Mortality (Bq-1) Morbidity (Bq'1) Dominant cancer % total type mortality , continued .OE-01 .OE-01 1 6 .73E-12 .17E-11 3 1 .07E-12 .08E-10 colon colon 65 73 .9 .9 Ruthenium Ru-103 Ru-106 Silver Ag-108m Ag-llOm Antimony Sb-124 Sb-125 Sb-126 Sb-127 Tellurium Te-125m Te-127m Te-127 Te-129m Te-129 Te-131m Te-132 Iodine 1-125 1-129 1-131 1-132 1-133 1-134 1-135 Cesium Cs-134 Cs-135 Cs-136 Cs-137 Barium Ba-133 Ba-140 5 5 5 5 1 1 1 1 3 3 3 3 3 3 3 1 1 1 1 1 1 1 1 1 1 1 2 2 .OE-02 .OE-02 .OE-02 .OE-02 .OE-01 .OE-01 .OE-01 .OE-01 .OE-01 .OE-01 .OE-01 .OE-01 .OE-01 .OE-01 .OE-01 .OE+00 .OE+00 .OE+00 .OE+00 .OE+00 .OE+00 .OE+00 .OE+00 .OE+00 .OE+00 .OE+00 .OE-01 .OE-01 8 9 1 2 2 1 2 2 7 2 2 3 4 1 2 9 5 1 9 6 4 1 9 1 2 6 1 3 .48E-11 .35E-10 .92E-10 .30E-10 .86E-10 .01E-10 .46E-10 .22E-10 .51E-11 .03E-10 .25E-11 .39E-10^ .55E-12 .30E-10 .78E-10 .64E-11 .31E-10 .85E-10 .22E-12 .51E-11 - .97E-12 .90E-11 .57E-10 .07E-10 .05E-10 .88E-10 .73E-10 .34E-10 1 1 3 3 5 1 4 3 1 3 3 5 6 3 6 9 5 1 3 5 9 1 1 1 3 1 2 5 .50E-10 .65E-09 .03E-10 .71E-10 .01E-10 .66E-10 .29E-10 .97E-10 .27E-10 .23E-10 .97E-11 .95E-10 .61E-12 .21E-10 .60E-10 .28E-10 .21E-09 .75E-09 .17E-11 .58E-10 .28E-12 .17E-10 .39E-09 .59E-10 .04E-10 .01E-09 .55E-10 .86E-10 colon colon colon colon colon colon colon colon colon colon colon colon stomach colon colon thyroid thyroid thyroid none thyroid stomach thyroid none none none none none colon 89 88 53 59 87 70 85 95 69 56 91 78 51 81 80 95 97 93 - 83 62 54 - - - - 89 .3 .5 .2 .4 .4 .2 .6 .1 .0 .8 .6 .9 .3 .1 .5 .6 .6 .7 .1 .6 .8 .4 Lanthanum La -140 Cerium Ce-141 Ce-144 Lead Pb-210 Pb-212 5 5 5 2 2 .OE-04 .OE-04 .OE-04 .OE-01 .OE-01 2 1 7 2 5 .41E-10 .02E-10 .73E-10 .31E-08 .95E-10 4 1 1 3 9 .30E-10 .83E-10 .40E-09 .18E-08 .59E-10 colon colon colon none colon 93 98 98 53 .2 .0 .5 .0 35 ------- Table 2.3a, continued Nuclide f. Bismuth Bi-210 5.0E-02 Bi-212 5.0E-02 Polonium Po-210 5.0E-01 Radium Ra-223 2.0E-01 Ra-224 2.0E-01 Ra-226 2.0E-01 Ra-228 2.0E-01 Actinium Ac-227 5.0E-04 Ac-228 5.0E-04 Protactinium Pa-231 5.0E-04 Pa-233 5.0E-04 Pa-234 5.0E-04 Thorium Th-227 5.0E-04 Th-228 5.0E-04 Th-230 5.0E-04 Th-231 5.0E-04 Th-232 5.0E-04 Th-234 5.0E-04 Uranium U-232 2.0E-02 U-233 2.0E-02 U-234 2.0E-02 U-235 2.0E-02 U-236 2.0E-02 U-238 2.0E-02 Neptunium ^-2363* 5.0E-04 Np-236b* 5.0E-04 Np-237 5.0E-04 Np-239 5.0E-04 Plutonium Pu-236 5.0E-04 Pu-238 5.0E-04 Pu-239 5.0E-04 Pu-240 5.0E-04 Pu-241 5.0E-04 Pu-242 5.0E-04 Americium Ara-241 5.0E-04 Mortality Morbidity (Bq-1) (Bq-1) 1.95E-10 1.88E-11 4.44E-08 5.63E-09 3.88E-09 7.15E-09 2.74E-08 5.34E-09 4.52E-11 6.15E-09 1.22E-10 5.77E-11 1.05E-09 2.46E-09 2.16E-09 4.86E-11 2.45E-09 5.07E-10 7.22E-09 1.69E-09 1.66E-09 1.62E-09 1.57E-09 1.51E-09 2.42E-10 2.46E-11 1.44E-09 1.13E-10 1.87E-09 3.50E-09 3.63E-09 3.63E-09 5.07E-11 3.45E-09 2.56E-09 * Np-236 isomer with half -life * Np-236 isomer with half-life 3.52E-10 2.71E-11 6.09E-08 9.15E-09 6.42E-09 1.05E-08 3.86E-08 6.63E-09 7.85E-11 8.73E-09 2.20E-10 l.OOE-10 1.87E-09 3.99E-09 3.22E-09 8.75E-11 3.60E-09 9.18E-10 1.04E-08 2.62E-09 2.58E-09 2.55E-09 2.44E-09 2.34E-09 3.90E-10 4.41E-11 2.24E-09 2.03E-10 2.68E-09 4.58E-09 4.70E-09 4.71E-09 6.17E-11 4.47E-09 3.63E-09 Dominant cancer type colon stomach none colon colon none none liver colon bone colon colon colon colon none colon none colon none colon colon colon colon colon colon colon colon colon none liver liver liver liver liver none X total mortality 95.9 49.8 - 60.4 63.7 - 53.9 87.1 44.9 97.2 86.8 94.0 '60.4 97.4 98.7 - 40.4 40.8 43.4 40.8 40.9 55.8 95.8 45.1 97.3 - 50.5 52.0 51.9 61.4 51.9 - Of 1.15X105 y. of 22.5 h. 36 ------- Table 2.3a, continued Nuclide Mortality Morbidity (Bq-1) (Bq'1) Dominant cancer X total type mortality Americium, continued Am-243 Curium Cm- 242 Cm -243 Cm- 244 5 5 5 5 .OE-04 .QE-04 .OE-04 .OE-04 2 8 2 2 .54E-09 .65E-10 .30E-09 .02E-09 3. 1. 3. 2. 61E-09 48E-09 33E-09 93E-09 none colon none none 83. - ,8 37 ------- ------- Table 2.3b. Mortality and morbidity risk coefficients for ingestion of iodine in food, based on usage of cow's milk. Explanation of Entries This table provides additional risk coefficients for intake of radioisotopes of iodine in diet. In this tabulation, the rate of intake of a radioisotope of iodine is assumed to be proportional to the ingestion rate of cow's milk. Risk coefficients for ingestion of radioisotopes of iodine in cow's milk are expressed as the probability of radiogenic cancer mortality or morbidity per unit intake, where the intake is averaged over all ages and both genders. The cancer type that makes the largest contribution to the total cancer mortality rate is given in the column labeled "dominant cancer type", and its percentage contribution to the total radiogenic cancer mortality is given in the column labeled "% total mortality". To facilitate application of the risk coefficients, including conversion to other units, the coefficients are tabulated to three decimal places. No indication of uncertainty is intended or should be inferred from this practice. To express a risk coefficient in conventional units (uCi'1), multiply by 3.7xl04 Bq ^iCf1. To express a risk coefficient in terms of a constant activity concentration in milk (Bq I/1), multiply the coefficient by 2.75 xlO4 UM, where UM is the lifetime average rate of ingestion of milk (for example, 0.243 L d"1 in Table 3.1) and 2.75xlO4 d is the average life span. Note that the relative age- and gender-specific energy intake rates specified in Table 3.1 are inherent in the risk coefficient. 39 ------- Table 2.3b. Mortality and morbidity risk coefficients for ingestion of iodine in food, based on usage of cow's milk. Isotope 1-125 1-129 1-131 1-132 1-133 1-134 1-135 fi l.OE+00 l.OE+00 l.OE+00 l.OE+00 l.OE+00 l.OE+00 l.OE+00 Mortality (Bq-1) 1.76E-10 8.86E-10 3.78E-10 1.65E-11 1.34E-10 8.64E-12 3.63E-11 Morbidity (Bq-1) 1.70E-09 8.69E-09 3.61E-09 6.33E-11 1.19E-09 1.74E-11 2.43E-10 Dominant cancer type thyroid thyroid thyroid none thyroid stomach thyroid % total mortality 95.8 97.7 94.6 - 86.5 61.8 61.3 40 ------- Table 2.4. Mortality and morbidity risk coefficients for external exposure from environmental media. Explanation of Entries Risk coefficients are provided for each of three external exposure scenarios: submersion in contaminated air, exposure from contamination on the ground surface, and exposure from soil contaminated to an infinite depth. It is assumed that the contaminated ground surface is an infinite plane and the contaminated air or soil occupies an infinite half-space. Risk coefficients are expressed as the probability of radiogenic cancer mortality or morbidity per unit time-integrated activity concentration in air, on the ground surface, or in soil. These risk coefficients are based on the dosimetric data of Federal Guidance Report No. 12 (EPA, 1993). Because the distribution of absorbed dose within the body is fairly uniform for most external exposures, the cancer type with the highest contribution to the total risk is not shown in this table. To facilitate application of the risk coefficients, including conversion to other units, the coefficients are tabulated to three decimal places. No indication of uncertainty is intended or should be inferred from this practice. To express a risk coefficient in terms of a constant activity concentration of the radionuclide in the environmental medium, multiply the coefficient by 2.37x109 s. To express a risk coefficient in conventional units of activity, multiply the coefficient by 3.7><104 BqjiCi"1. To express arisk coefficient in time units of year (y), multiply the coefficient by 3.16*107 s y'1. To express a risk coefficient for submersion in volume units of cm3, multiply the coefficient by Ixl06cm3m-3. To express a risk coefficient for ground plane in area units of cm2, multiply the coefficient by Ixl04cm2m-2. To express a risk coefficient for soil in mass units of g, multiply the coefficient by 1 xlO3 g kg"1. 41 ------- Table 2.4. Mortality and morbidity risk coefficients for external exposure from environmental media. Mortality Submersion Nuclide m3/Bq-s Ground Plane ra2/Bq-s Morbidity Soil Submersion kg/Bq-s m3/Bq-s Ground Plane m2/Bq-s Soil kg/Bq-s Hydrogen H-3 Carbon C-14 Sulfur S-35 Argon Ar-37 Ar-39 Ar-41 Calcium Ca-45 Ca-47 O.OOE+00 3.23E-20 3.79E-20 O.OOE+00. 1.46E-18 3.38E-15 1.79E-19 2.78E-15 0 5 5 0 3 6 1 5 .OOE+00 .30E-22 .60E-22 .OOE+00 .67E-20 .54E-17 .69E-21 .41E-17 0 4 5 0 3 3 2 3 .OOE+00 .46E-21 .OOE-21 .OOE+00 .46E-19 .73E-15 .28E-20 .06E-15 0. 3. 4. 0. 1. 4. 1. 4. OOE+00 66E-20 27E-20 OOE+00 66E-18 96E-15 97E-19 09E-15 0. 8. 8. 0. 4. 9. 2. 7. OOE+00 24E-22 68E-22 OOE+00 39E-20 60E-17 59E-21 95E-17 0 6 7 0 5 5 3 4 .OOE+00 .71E-21 .51E-21 .OOE+00 .09E-19 .47E-15 .39E-20 .49E-15 Scandium Sc-47 Iron Fe-55 Fe-59 Cobalt Co -57 Co -58 Co -60 Nickel Ni-59 Ni-63 Zinc Zn-65 Selenium Se-75 Se-79 Krypton Kr-74 Kr-76 Kr-77 Kr-79 Kr-81m Kr-81 Kr-83m Kr-85m Kr-85 Kr-87 Kr-88 2.46E-16 O.OOE+00 3.09E-15 2.63E-16 2.43E-15 6.55E-15 O.OOE+00 O.OOE+00 1.50E-15 9.02E-16 4.80E-20 2.81E-15 1.01E-15 2.43E-15 6.09E-16 2.97E-16 1.32E-17 4.44E-20 3.61E-16 7.23E-18 2.15E-15 5.37E-15 5 0 6 5 5 1 0 0 2 1 6 6 2 5 1 6 3 1 8 2 4 9 .39E-18 .OOE+00 .05E-17 .86E-18 .07E-17 .27E-16 .OOE+00 .OOE+00 .97E-17 .97E-17 .94E-22 .16E-17 .20E-17 .34E-17 .31E-17 .45E-18 .06E-19 .07E-20 .OOE-18 .15E-19 .06E-17 .45E-17 2 0 3 2 2 7 0 0 1 8 6 2 1 2 6 2 1 6 3 6 2 5 .HE -16 .OOE+00 .40E-15 .07E-16 .62E-15 .23E-15 .OOE+00 .OOE+00 .64E-15 .41E-16 .25E-21 .86E-15 .01E-15 .46E-15 .29E-16 .68E-16 .27E-17 .99E-21 .18E-16 .15E-18 .34E-15 .94E-15 3. 0. 4. 3. 3. 9. 0. 0. 2. 1. 5. 4. 1. 3. 8. 4. 1. 7. 5. 1. 3. 7. 63E-16 OOE+00 54E-15 89E-16 58E-15 63E-15 OOE+00 OOE+00 20E-15 33E-15 39E-20 13E-15 49E-15 58E-15 97E-16 38E-16 94E-17 61E-20 33E-16 OOE-17 16E-15 89E-15 7. 0. 8. 8. 7. 1. 0. 0. 4. 2. 1. 9. 3. 7. 1. 9. 4. 1. 1. 2. 5. 1. 92E-18 OOE+00 90E-17 63E-18 46E-17 87E-16 OOE+00 OOE+00 37E-17 89E-17 08E-21 03E-17 24E-17 83E-17 92E-17 49E-18 54E-19 76E-20 17E-17 79E-19 92E-17 39E-16 3 0 4 3 3 1 0 0 2 1 9 4 1 3 9 3 1 1 4 9 3 8 .10E-16 .OOE+00 .99E-15 .04E-16 .84E-15 .06E-14 .OOE+00 .OOE+00 .41E-15 .24E-15 .40E-21 .20E-15 .48E-15 .61E-15 .24E-16 .94E-16 .87E-17 .15E-20 .68E-16 .02E-18 .43E-15 .72E-15 42 ------- Table 2.4, continued Mortality Submersion Nuclide m3/Bq-s Bromine Br-74 1. Br-76 6. Br-77 7. Rubidium Rb-87 3. Rb-88 1. Strontium Sr-89 7. Sr-90 1. Yttrium Y-90 1. Zirconium Zr-95 1. Niobium Nb-94 3. Nb-95m 1. Nb-95 1. 25E-14 95E-15 60E-16 87E-19 77E-15 30E-18 24E-18 53E-17 84E-15 94E-15 44E-16 91E-15 2 1 1 3 3 7 2 1 3 8 3 3 Ground Plane m2/Bq-s .19E-16 .32E-16 .63E-17 .36E-21 .37E-17 .72E-19 .60E-20 .31E-18 .85E-17 .18E-17 .17E-18 .99E-17 Soil kg/Bq-s 1 7 7 5 1 4 2 1 1 4 1 2 .36E-14 .54E-15 .81E-16 .25E-20 .96E-15 .37E-18 .80E-19 .16E-17 .98E-15 .25E-15 .35E-16 .06E-15 Submersion m3/Bq-s 1 1 1 4 2 9 1 1 2 5 2 2 .84E-14 .02E-14 .12E-15 .25E-19 .60E-15 .04E-18 .40E-18 .96E-17 .71E-15 .79E-15 .12E-16 .81E-15 Morbidity Ground Plane nr/Bq-s 3 1 2 5 4 8 3 1 5 1 4 5 .21E-16 .93E-16 .41E-17 .11E-21 .88E-17 .25E-19 .20E-20 .43E-18 .68E-17 .21E-16 .68E-18 .88E-17 Soil kg/Bq-s 1 1 1 7 2 6 4 1 2 6 1 3 .99E-14 .HE -14 .15E-15 .80E-20 .88E-15 .16E-18 .13E-19 .64E-17 .91E-15 .24E-15 .99E-16 .02E-15 Molybdenum Mo-99 3. 71E-16 8 .16E-18 3 .87E-16 5 .45E-16 1 .18E-17 5 .69E-16 Technetium Tc-95m 1. Tc-95 1. Tc-99m 2. Tc-99 3. Ruthenium Ru-103 1. Ru-106 0. Rh-103m 2. Rh-106 5. Silver Ag-108m 3. Ag-108 5. Ag-llOm 6. Ag-110 9. Antimony Sb-124 4. Sb-125 1. Sb-126 7. Sb-127 1. Tellurium Te-125m 1. Te-127m 4. 63E-15 96E-15 79E-16 38E-19 14E-15 OOE+00 17E-19 36E-16 96E-15 06E-17 97E-15 81E-17 74E-15 02E-15 OOE-15 69E-15 32E-17 49E-18 3 4 6 2 2 0 2 1 8 1 1 3 9 2 1 3 1 3 .45E-17 .10E-17 .15E-18 .98E-21 .45E-17 .OOE+00 .85E-20 .26E-17 .44E-17 .74E-18 .42E-16 .27E-18 .22E-17 .22E-17 .48E-16 .61E-17 .04E-18 .30E-19 1 2 2 4 1 0 4 5 4 5 7 9 5 1 7 1 3 1 .71E-15 .12E-15 .29E-16 .69E-20 .19E-15 .OOE+00 .75E-20 .64E-16 .19E-15 .01E-17 .57E-15 .97E-17 .18E-15 .06E-15 .47E-15 .79E-15 .77E-18 .51E-18 2 2 4 3 1 0 3 7 5 7 1 1 6 1 1 2 2 7 .40E-15 .89E-15 .12E-16 .72E-19 .67E-15 .OOE+00 .78E-19 .85E-16 .82E-15 .27E-17 .03E-14 .41E-16 .97E-15 .50E-15 .03E-14 .49E-15 .14E-17 .18E-18 5 6 9 4 3 0 4 1 1 2 2 4 1 3 2 5 1 5 .08E-17 .04E-17 .06E-18 .53E-21 .61E-17 .OOE+00 .79E-20 .80E-17 .24E-16 .23E-18 .09E-16 .22E-18 .35E-16 .27E-17 .18E-16 .31E-17 .65E-18 .21E-19 2 3 3 6 1 0 7 8 6 7 1 1 7 1 1 2 5 2 .51E-15 .HE -15 .37E-16 .97E-20 .75E-15 .OOE+00 .97E-20 .27E-16 .15E-15 .33E-17 .HE -14 .45E-16 .61E-15 .55E-15 .10E-14 .63E-15 .95E-18 .34E-18 43 ------- Table 2.4, continued Mortality Nuclide Submersion m3/Bq-s Tellurium, Te-127 Te-129m Te-129 Te-131m Te-131 Te-132 Iodine 1-125 1-129 1-131 1-132 1-133 1-134 1-135 Xenon Xe-120 Xe-121 Xe-122 Xe-123 Xe-125 Xe-127 Xe-129m Xe-131m Xe-133ra Xe-133 Xe-135ra Xe-135 Xe-138 Cesium Cs-134 Cs-135 Cs-136 Cs-137 Cs-138 Cerium Ce-141 Ce-144 1 7 1 3 1 4 1 1 9 5 1 6 4 9 4 1 1 5 6 4 1 6 6 1 5 3 3 1 5 1 6 1 3 Ground Plane nr/Bq-s Soil kg/Bq-s Morbidity Submersion m3/Bq-s Ground Plane m2/Bq-s Soil kg/Bq-s continued .32E-17 .83E-17 .41E-16 .59E-15 .03E-15 .97E-16 .48E-17 .17E-17 .14E-16 .73E-15 .50E-15 .68E-15 .15E-15 .69E-16 .73E-15 .16E-16 .53E-15 .79E-16 .01E-16 .06E-17 .47E-17 .30E-17 .59E-17 .03E-15 .87E-16 .01E-15 .86E-15 .12E-19 .44E-15 .20E-18 .31E-15 .62E-16 .90E-17 3.22E-19 2.03E-18 3.63E-18 7.31E-17 2.24E-17 1.13E-17 1.22E-18 8.05E-19 1.98E-17 1.19E-16 3.21E-17 1.36E-16 7.96E-17 2.15E-17 9.04E-17 3.03E-18 3.20E-17 1.31E-17 1.37E-17 1.82E-18 6.88E-19 1.74E-18 1.96E-18 2.24E-17 1.29E-17 5.61E-17 8.11E-17 1.18E-21 1.11E-16 3.96E-20 1.19E-16 3.69E-18 9.61E-19 1 8 1 3 1 4 3 3 9 6 1 7 4 9 5 1 1 5 5 2 8 5 3 1 5 3 4 1 5 3 6 1 2 .22E-17 .05E-17 .43E-16 .86E-15 .04E-15 .57E-16 .89E-18 .34E-18 .28E-16 .18E-15 .58E-15 .25E-15 .57E-15 .91E-16 .09E-15 .07E-16 .59E-15 .46E-16 .54E-16 .44E-17 .11E-18 .38E-17 .83E-17 .09E-15 .66E-16 .28E-15 .14E-15 .35E-20 .86E-15 .14E-19 .93E-15 .32E-16 .92E-17 1 1 2 5 1 7 2 1 1 8 2 9 6 1 6 1 2 8 8 6 2 9 9 1 8 4 5 1 8 1 9 2 5 .89E-17 .15E-16 .06E-16 .28E-15 .51E-15 .35E-16 .41E-17 .85E-17 .35E-15 .43E-15 .20E-15 .83E-15 .10E-15 .43E-15 .95E-15 .72E-16 .26E-15 .56E-16 .88E-16 .19E-17 .24E-17 .34E-17 .86E-17 .52E-15 .65E-16 .42E-15 .68E-15 .23E-19 .01E-15 .37E-18 .27E-15 .39E-16 .78E-17 4 2 5 1 3 1 1 1 2 1 4 2 1 3 1 4 4 1 2 2 1 2 2 3 1 8 1 1 1 4 1 5 1 .50E-19 .91E-18 .10E-18 .08E-16 .26E-17 .68E-17 .94E-18 .26E-18 .92E-17 .75E-16 .71E-17 .OOE-16 .17E-16 .17E-17 .33E-16 .54E-18 .71E-17 .94E-17 .02E-17 .80E-18 .06E-18 .61E-18 .93E-18 .30E-17 .89E-17 .22E-17 .19E-16 .81E-21 .64E-16 .57E-20 .75E-16 .44E-18 .42E-18 1. 1. 2. 5. 1. 6. 6. 5. 1. 9. 2. 1. 6. 1. 7. 1. 2. 8. 8. 3. 1. 7. 5. 1. 8. 4. 6. 2. 8. 4. 1. 1. 4. 80E-17 18E-16 10E-16 66E-15 53E-15 71E-16 20E-18 22E-18 36E-15 08E-15 33E-15 06E-14 71E-15 46E-15 48E-15 57E-16 33E-15 03E-16 15E-16 64E-17 21E-17 92E-17 67E-17 59E-15 31E-16 81E-15 08E-15 02E-20 60E-15 56E-19 02E-14 94E-16 30E-17 Praseodymium Pr-144ra Pr-144 Barium Ba-133 Ba-137m 1 1 8 1 .01E-17 .09E-16 .70E-16 .47E-15 4.75E-19 3.27E-18 1.99E-17 3.12E-17 4 1 8 1 .99E-18 .14E-16 .37E-16 .57E-15 1 1 1 2 .56E-17 .56E-16 .28E-15 .16E-15 7 4 2 4 .23E-19 .22E-18 .95E-17 .60E-17 7. 1. 1. 2. 48E-18 66E-16 23E-15 30E-15 44 ------- Table 2.4, continued Mortality Submersion Nuclide m3/Bq-s Ground Plane m2/Bq-s Soil kg/Bq-s Morbidity Submersion m3/Bq-s Ground Plane it)2/Bq-s Soil kg/Bq-s Barium, continued Ba-140 4. Lanthanum La-140 6. Thallium Tl-207 1. T1-2Q8 9. Tl-209 5. Lead Pb-210 2. Pb-211 1. Pb-212 3. Pb-214 5. Bismuth Bi-210 3. Bi-211 1. Bi-212 4. Bi-214 3. Polonium Po-210 2. Po-211 1. Po-212 0. Po-214 2. Po-215 4. Po-216 4. Po-218 2. Radon Rn-218 1. Rn-219 1. Rn-220 9. Rn-222 9. Francium Fr-223 1. Radium Ra-223 2. Ra-224 2. Ra-226 1. Ra-228 0. Actinium Ac-227 2. Ac-228 2. 32E-16 10E-15 HE -17 33E-15 30E-15 11E-18 29E-16 31E-16 85E-16 79E-18 10E-16 78E-16 98E-15 13E-20 95E-17 OOE+00 09E-19 24E-19 24E-20 30E-20 86E-18 33E-16 40E-19 67E-19 06E-16 91E-16 30E-17 51E-17 OOE+00 67E-19 45E-15 9. 1. 7. 1. 1. 9. 3. 7. 1. 3. 2. 1. 7. 4. 4. 0. 4. 9. 8. 4. 3. 2. 2. 2. 2. 6. 5. 3. 0. 6. 4. 57E-18 17E-16 10E-19 62E-16 03E-16 43E-20 15E-18 35E-18 28E-17 89E-19 41E-18 01E-17 65E-17 43E-22 06E-19 OOE+00 34E-21 21E-21 82E-22 74E-22 96E-20 89E-18 02E-20 09E-20 94E-18 55E-18 OOE-19 32E-19 OOE+00 91E-21 99E-17 4 6 8 1 5 8 1 2 5 1 1 5 4 2 2 0 2 4 4 2 1 1 9 1 8 2 2 1 0 2 2 .44E-16 .70E-15 .95E-18 .03E-14 .74E-15 .06E-19 .34E-16 .97E-16 .72E-16 .66E-18 .10E-16 .18E-16 .37E-15 .30E-20 .09E-17 .OOE+00 .2SE-19 .36E-19 .59E-20 .48E-20 .97E-18 .31E-16 .91E-19 .01E-18 .16E-17 .53E-16 .17E-17 .33E-17 .OOE+00 .02E-19 .64E-15 6 8 1 1 7 3 1 4 8 4 1 7 5 3 2 0 3 6 6 3 2 1 1 1 1 4 3 2 0 3 3 .36E-16 .96E-15 .49E-17 .37E-14 .79E-15 .22E-18 .89E-16 .89E-16 .62E-16 .52E-18 .62E-16 .02E-16 .85E-15 .13E-20 .86E-17 .OOE+00 .07E-19 .24E-19 .24E-20 .38E-20 .73E-18 .96E-16 .38E-18 .42E-18 .57E-16 .30E-16 .40E-17 .23E-17 .OOE+00 .96E-19 .61E-15 1 1 8 2 1 1 4 1 1 4 3 1 1 6 5 0 6 1 1 6 5 4 2 3 4 9 7 4 0 1 7 .40E-17 .71E-16 .01E-19 .37E-16 .50E-16 .43E-19 .42E-18 .08E-17 .89E-17 .13E-19 .54E-18 .46E-17 .12E-16 .52E-22 .98E-19 .OOE+00 .39E-21 .36E-20 .30E-21 .99E-22 .83E-20 .25E-18 .97E-20 .08E-20 .23E-18 .64E-18 .35E-19 .89E-19 .OOE+00 .04E-20 .33E-17 6 9 1 1 8 1 1 4 8 2 1 7 6 3 3 0 3 6 6 3 2 1 1 1 1 3 3 1 0 2 3 .52E-16 .83E-15 .30E-17 .51E-14 .42E-15 .21E-18 .96E-16 .36E-16 .41E-16 .36E-18 .61E-16 .60E-16 .41E-15 .38E-20 .07E-17 .OOE+00 .31E-19 .41E-19 .74E-20 .65E-20 .90E-18 .93E-16 .46E-18 .49E-18 .20E-16 .72E-16 .19E-17 .96E-17 .OOE+00 .98E-19 .88E-15 Protactinium Pa-231 8. Pa-233 4. 41E-17 58E-16 1. 1. 96E-18 01E-17 8 4 .09E-17 .32E-16 1 6 .24E-16 .75E-16 2 1 .92E-18 .49E-17 1 6 .19E-16 .36E-16 45 ------- Table 2.4, continued Mortality Ground Submersion Plane Nucl i de m3/Bq - s m2/Bq - s Soil kg/Bq-s Morbidity Ground Submersion Plane m3/Bq-s mz/Bq-s Soil kg/Bq-s Protactinium, continued Pa-234m Pa -234 Thorium Th-227 Th-228 Th-230 Th-231 Th-232 Th-234 Uranium U-232 U-233 U-234 U-235 U-236 U-238 4.17E-17 4.77E-15 2.37E-16 4.24E-18 7.46E-19 2.25E-17 3.51E-19 1.50E-17 5.66E-19 7.24E-19 2.79E-19 3.45E-16 1.66E-19 9.95E-20 Neptunium Np-236af 2.48E-16 Np-236b* 9.99E-17 Np-237 Np-239 4.56E-17 3.67E-16 1 9 5 1 2 7 1 3 2 2 2 7 1 1 5 2 1 8 .73E-18 .81E-17 .30E-18 .07E-19 .69E-20 .05E-19 .73E-20 .86E-19 .97E-20 .51E-20 .01E-20 .60E-18 .65E-20 .34E-20 .81E-18 .31E-18 .24E-18 .24E-18 4.04E-17 5 2 3 4 1 1 9 3 5 1 3 7 2 1 7 3 3 .08E-15 .20E-16 .25E-18 .74E-19 .42E-17 .97E-19 .52E-18 .45E-19 .70E-19 .44E-19 .02E-16 .03E-20 .70E-20 .89E-16 .81E-17 .HE -17 .15E-16 5. 7. 3. 6. 1. 3. 5. 2. 8. 1. 4. 5. 2. 1. 3. 1. 6. 5. 88E-17 02E-15 50E-16 29E-18 12E-18 36E-17 35E-19 23E-17 67E-19 09E-18 37E-19 09E-16 67E-19 66E-19 67E-16 48E-16 79E-17 42E-16 2. 1. 7. 1. 4. 1. 2. 5. 4. 3. 3. 1. 2. 2. 8. 3. 1. 1. HE -18 44E-16 81E-18 60E-19 17E-20 08E-18 74E-20 74E-19 78E-20 91E-20 29E-20 12E-17 73E-20 25E-20 62E-18 41E-18 86E-18 22E-17 5 7 3 4 7 2 2 1 5 8 2 4 1 4 2 1 4 4 .88E-17 .46E-15 .24E-16 .79E-18 .01E-19 .10E-17 .93E-19 .40E-17 .12E-19 .41E-19 .16E-19 .44E-16 .07E-19 .27E-20 .78E-16 .15E-16 .59E-17 .63E-16 Plutonium Pu-236 Pu-238 Pu-239 Pu-240 Pu-241 Pu-242 1.87E-19 1.34E-19 1.65E-19 1.31E-19 3.29E-21 1.12E-19 2 1 9 1 8 1 .33E-20 .95E-20 .99E-21 .88E-20 .44E-23 .57E-20 6 3 1 3 2 3 .56E-20 .88E-20 .15E-19 .76E-20 .39E-21 .38E-20 3. 2. 2. 2. 4. 1. 13E-19 28E-19 56E-19 24E-19 89E-21 91E-19 3. 3. 1. 3. 1. 2. 92E-20 30E-20 63E-20 17E-20 27E-22 64E-20 1 6 1 5 3 5 .02E-19 .18E-20 .71E-19 .98E-20 .52E-21 .35E-20 AmericiUm Am-241 Am-243 Curium Cm-242 Cm-243 Cra-244 * Np-236 * Np-236 3.33E-17 9.45E-17 1.50E-19 2.81E-16 1.22E-19 1 2 2 6 2 isomer with isomer with .HE -18 .51E-18 .20E-20 .31E-18 .OOE-20 1 5 4 2 2 half -life half -life .59E-17 .49E-17 .10E-20 .44E-16 .46E-20 5. 1. 2. 4. 2. of 1.15xl05 of 22.5 h. OOE-17 41E-16 59E-19 16E-16 15E-19 y- 1. 3. 3. 9. 3. 68E-18 71E-18 71E-20 31E-18 39E-20 2 8 6 3 4 .36E-17 .11E-17 .62E-20 .59E-16 .15E-20 46 ------- CHAPTERS. EXPOSURE SCENARIOS The risk coefficients developed in this report are gender-averaged values based on biokinetic, dosimetric, and radiation risk models that represent typical or "reference" male and female members of the U.S. population, from infancy through old age. Although the coefficients may be interpreted in terms of either acute or chronic exposure, computations are based on the assumption that these persons are exposed throughout life, beginning at birth, to a constant concentration of a radionuclide in a given environmental medium. In utero exposures are not considered in this document. Characteristics of the exposed population The physical characteristics of the reference male and reference female at different ages are described in reports by Cristy and Eckerman (1987, 1993). The vital statistics for these reference persons are based on the 1989-91 U.S. decennial life table (NCHS, 1997) and U.S. cancer mortality data for the same period (NCHS, 1992,1993a, 1993b). That is, it is assumed that the exposed male and female are subject to the risk of dying from a competing cause (any cause other than a cancer produced by the radiation exposure hypothesized here) indicated by the 1989-91 U.S. decennial life table and are subject to the risk of experiencing or dying from cancer at a specific site indicated by U.S. cancer mortality data for the same period. Gender-specific survival functions (fractions of live- born individuals surviving to different ages) for the stationary population are shown in Fig. 3.1. Methods of extending or smoothing the U.S. vital statistics for use in this report are described in Appendix A. Growth of decay chain members For each of the internal exposure scenarios, the risk coefficient for a radionuclide includes the contribution to dose from production of decay chain members in the body after intake of the parent radionuclide. However, for either an internal or external exposure scenario, the risk coefficient for a given radionuclide is based on the assumption that this is the only radionuclide present in the environmental medium. Growth of chain members in the environment is not considered because this would require the assumption of a temporal pattern of contamination and environmental behavior of decay chain members and thus would limit the applicability of the risk coefficients. For each of the radionuclides addressed in this document, however, a separate risk 47 ------- 100 120 Age (y) Fig. 3.1. Gender-specific survival functions for the stationary population. coefficient is provided for any subsequent chain member that is of potential dosimetric significance. This enables the user to assess the risks from ingrowth of radionuclides in the environment. Inhalation of radionuclides Risk coefficients (Bq"1) for inhalation of radionuclides in air are expressed as risk of cancer mortality or morbidity per unit activity intake. The age- and gender-specific inhalation rates used in this report (Table 3.1, Fig. 3.2) are taken from ICRP Publication 66 (1994a). These inhalation rates are based on breathing rates measured during periods of rest, light activity, or heavy activity. The average 24-h ventilation rate is estimated as a time-weighted average of ventilation rates for rest periods and periods of light and heavy activity. Recently, Layton (1993) proposed a different approach for the estimation of average inhalation rates at different ages. Estimates are based on typical oxygen consumption associated with energy expenditure and are derived using the equation VE = E * H x VQ, where VE is the 48 ------- ventilation rate (L min"1), E is the average rate of energy expenditure (kilojoules min"1), His the volume of oxygen (at standard temperature and pressure) consumed in the production of 1 kilojoule 49 ------- Table 3.1. Age- and gender-specific usage rates of environmental media, for selected ages.3 Air" (m3 d'1) Age (y) 0 1 5 10 15 20 50 75 Lifetime average Combined lifetime average' M 2.9 5.2 8.8 15.3 20.1 22.2 22.2 22.2 19.2 F 2.9 5.2 8.8 15.3 15.7 17.7 17.7 17.7 16.5 17.8 Tap water0 (Ld-1) M 0.191 0.223 0.542 0.725 0.900 1.137 1.643 1.564 1.29 1.11 F 0.188 0.216 0.499 0.649 0.712 0.754 1.119 1.179 0.93 Food energyd (kcal d'1) M 478 791 1566 1919 2425 2952 2570 1990 2418 F 470 752 1431 1684 1828 1927 1758 1508 1695 20489 Cow's milk6 (Ld-1) M 0.339 0.349 0.413 0.486 0.519 0.414 0.192 0.192 0.282 F 0.350 0.358 0.409 0.428 0.356 0.249 0.139 ' 0.139 0.207 0.243 "All values are based on estimated averages for the U.S. population for the indicated age. Ages refer to birthdays; e.g., a given rate at age 5 y indicates the rate on the fifth birthday. Data reported for age intervals were converted to point estimates by preserving the total intake in each interval using a cubic spline fitting method (Fritsch and Carlson, 1980). Fitted curves were smoothed using a 3-point moving average. The listed usage rates are the values used in the calculation and are generally more precise than the data would support. bFrom Tables B.16A and B.16B of ICRP Publication 66, 1994a. 'Based on survey data of the U.S. Department of Agriculture (Ershow and Cantor, 1989). Includes drinking water, water added to beverages, and water added to foods during preparation, but not water intrinsic in food as purchased. dBascd on data from the Third National Health and Nutrition Examination Survey (McDowell et al., 1994). "Used in one of two scenarios for ingestion of radioisotopes of iodine in diet. The other scenario assumes that iodine intake is proportional to food energy usage. Milk usage is based on data from EPA report 520/1-84-021 (1984b). *Based on the male-to-female ratio at birth, the gender-specific survival function, and the gender-specific usage function. 8For a typical U.S. diet, equivalent to a lifetime average intake of about 1.2 kg food d"1 (see text). 50 ------- ------- .30 '25 "-'20 o ^ 4 c i- 15 I" « 5 c ~ 0 Male Female 10 15 Age (y) 20 25 30 2.0 d,1'5 0 J£ <9 1.0 |