Society News Archive

12 July 2013
NCRP Commentary on Risk Based on NCRP Report 171

The National Council on Radiation Protection and Measurements (NCRP) Scientific Committee (SC) 1-16 prepared a commentary that was recently published in the September 2013 volume of the Journal of Radiological Protection. This commentary is an overview of the committee's NCRP Report No. 171, Uncertainties in the Estimation of Radiation Risks and Probability of Disease Causation (2012). The journal is currently allowing free access to the full-text pdf of this commentary at

The commentary provides a timely overview of the topic, given that quantitative uncertainty analysis is the state of the art in health risk assessment and given its potential importance to developments in radiation protection. Over the past decade, the increasing volume of epidemiology data and the supporting radiobiology findings have aided in the reduction of uncertainty in the risk estimates derived. However, it is equally apparent that there remain significant uncertainties related to dose assessment, low dose and low dose-rate extrapolation approaches (e.g., the selection of an appropriate dose and dose-rate effectiveness factor), the biological effectiveness where considerations of the health effects of high-LET and lower-energy low-LET radiations are required, and the transfer of risks from a population for which health effects data are available to one for which such data are not available.

The impact of radiation on human health has focused in recent years on cancer, although there has been a decided increase in the data for noncancer effects together with more reliable estimates of the risk following radiation exposure, even at relatively low doses (notably for cataracts and cardiovascular disease).

New approaches for the estimation of hereditary risk have been developed with the use of human data whenever feasible, although the current estimates of heritable radiation effects still are based on mouse data because of an absence of effects in human studies. Uncertainties associated with estimation of these different types of health effects are discussed in a qualitative and semiquantitative manner as appropriate. The way forward would seem to require additional epidemiological studies, especially studies of low dose and low dose-rate occupational and perhaps environmental exposures and for exposures to x rays and high-LET radiations used in medicine.