Grant Number:	2R01CA242852-05A1 Interpret this number
Primary Investigator:	Richardson, David
Organization:	University Of California-Irvine
Project Title:	Low-Dose Exposure to Ionizing Radiation in Adulthood and Subsequent Cancer
Fiscal Year:	2026

ABSTRACT Since the 1980s, the US public’s exposure to ionizing radiation has increased, largely due to increasing radiation from diagnostic medical procedures such as computed tomography (CT) exams. The doses from such procedures are typically low but may be repeated over time and increase in frequency in later life. Quantitative estimates of radiation-associated cancer risk are primarily derived from the study of Japanese atomic bomb survivors. Questions have been raised about the appropriateness of using a study of atomic bomb survivors as the basis for contemporary estimates of radiation risk from protracted, low dose exposures. The parent study for this proposal assembled an international cohort of 308,000 radiation dosimeter-monitored workers from some of the world’s most informative cohorts in the United Kingdom, France, and USA, in a project called INWORKS. Here, we propose a major update that extends follow-up of each national cohort by at least 10 years, anticipated to yield more than a fifty percent increase in the number of cancer cases in the pooled analysis and support an innovative set of analyses to directly address questions relevant to radiation protection for low dose exposure to ionizing radiation in adulthood: 1) radiation-associated risks for solid cancer and leukemia; 2) cancer site-specific radiation risks; 3) cumulative absolute excess cancer risk estimates and their coherence with the risk models currently used to inform radiation protection and decision- making; 4) modification of site-specific excess relative rates (per unit dose) with time since exposure and age-at-exposure; and, 5) combined analyses of information from INWORKS and the Japanese atomic bomb survivor data to yield superior estimates of low dose radiation- cancer mortality associations. We leverage state-of-the-art G-estimation methods for cumulative risk estimation, Bayesian methods for data smoothing, and applied decision theory to guide policy-relevant summarizations of these empirical data. The study will provide a direct assessment of radiation risk following protracted, low dose radiation exposures in adulthood; and the findings will complement evidence regarding radiation risks derived from the study of Japanese atomic bomb survivors. The proposed study builds logically upon results of the highly successful parent study and is likely to exert a sustained influence on the field and make a major contribution to national and international radiation protection recommendations. Research outputs will be disseminated via peer-reviewed journals, presentations, a project website, and engagement with radiation protection organizations.




Author's response to the letter 'Worker studies and their Interpretation' by Richardsonet al.
Authors: Wakeford R. .
Source: Journal Of Radiological Protection : Official Journal Of The Society For Radiological Protection, 2025-07-14 00:00:00.0; 45(3), .
EPub date: 2025-07-14 00:00:00.0.
PMID: 40654093
Related Citations

Worker studies and their interpretation.
Authors: Richardson D.B. , Laurier D. , Haylock R. , Kelly-Reif K. , Bertke S. , Daniels R.D. , Thierry-Chef I. , Kesminiene A. , Schubauer-Berigan M.K. .
Source: Journal Of Radiological Protection : Official Journal Of The Society For Radiological Protection, 2025-07-14 00:00:00.0; 45(3), .
EPub date: 2025-07-14 00:00:00.0.
PMID: 40654101
Related Citations

Site-specific cancer mortality after low-level exposure to ionizing radiation: findings from an update of the International Nuclear Workers Study (INWORKS).
Authors: Richardson D.B. , Laurier D. , Leuraud K. , Gillies M. , Haylock R. , Kelly-Reif K. , Bertke S. , Daniels R.D. , Thierry-Chef I. , Moissonnier M. , et al. .
Source: American Journal Of Epidemiology, 2025-05-07 00:00:00.0; 194(5), p. 1285-1294.
PMID: 39108174
Related Citations

Correction to: Effect of L-alanine exposure during early life stage on olfactory development, growth and survival in age-0 lake sturgeon.