National Council on Radiation Protection and Measurements,
Bethesda, MD, 2005, 267 pages
Recommendations of the NATIONAL COUNCIL ON RADIATION PROTECTION AND MEASUREMENTS
This Report reviews the scientific issues associated with the extrapolation of radiation-induced cancer risks from nonhuman experimental systems to humans. The basic principles of radiation effects at the molecular and cellular level are examined with emphasis on comparisons among various species including humans. These comparisons among species are then continued for cancers of similar cell types in the same organ system. Risk estimates are made from an observed level of effect as a function of organ dose. The major organ systems are individually considered. Extrapolation models are reviewed and include exteal and inteal radiation exposures.
This Report includes a discussion of nontargeted radiation effects that potentially influence dose-response characteristics of cells and tissues at low absorbed doses. These nontargeted effects
include bystander effects, genomic instability, and adaptive radiation responses, all of which are subjects of presently active research. It is anticipated that future NCRP reports will analyze the influence of these factors on radiation dose-response characteristics and variations in radiation response(s) among species.
This Report gives an account of the steps by which a group of researchers has advanced the pragmatic and theoretical approaches to extrapolation of estimates of risk from radionuclides
and exteal radiation. The Report identifies the problems in extrapolating the current data from, for example, mice to humans. It provides examples of using Bayesian statistics to successfully
estimate DDREF values for humans from data for mice, and also provides a measure of uncertainty for this estimate. The Report also shows how a defensible quantitative estimate of radiation injury can be determined for humans even when the exposure data of interest are either lacking or of poor quality, and how mortality data for laboratory animals can be used to predict age-specific radiation- induced risks for humans for general endpoints like life shortening, all cancers, and selected subsets of cancers involving homologous tissues.
Recommendations of the NATIONAL COUNCIL ON RADIATION PROTECTION AND MEASUREMENTS
This Report reviews the scientific issues associated with the extrapolation of radiation-induced cancer risks from nonhuman experimental systems to humans. The basic principles of radiation effects at the molecular and cellular level are examined with emphasis on comparisons among various species including humans. These comparisons among species are then continued for cancers of similar cell types in the same organ system. Risk estimates are made from an observed level of effect as a function of organ dose. The major organ systems are individually considered. Extrapolation models are reviewed and include exteal and inteal radiation exposures.
This Report includes a discussion of nontargeted radiation effects that potentially influence dose-response characteristics of cells and tissues at low absorbed doses. These nontargeted effects
include bystander effects, genomic instability, and adaptive radiation responses, all of which are subjects of presently active research. It is anticipated that future NCRP reports will analyze the influence of these factors on radiation dose-response characteristics and variations in radiation response(s) among species.
This Report gives an account of the steps by which a group of researchers has advanced the pragmatic and theoretical approaches to extrapolation of estimates of risk from radionuclides
and exteal radiation. The Report identifies the problems in extrapolating the current data from, for example, mice to humans. It provides examples of using Bayesian statistics to successfully
estimate DDREF values for humans from data for mice, and also provides a measure of uncertainty for this estimate. The Report also shows how a defensible quantitative estimate of radiation injury can be determined for humans even when the exposure data of interest are either lacking or of poor quality, and how mortality data for laboratory animals can be used to predict age-specific radiation- induced risks for humans for general endpoints like life shortening, all cancers, and selected subsets of cancers involving homologous tissues.