Risk of Cancer Mortality from Occupational Exposure to Ionising Radiation: Results of the International Cohort Study of Radiation Workers (INWORKS)

Ausrele KESMINIENE, International Agency for Research on Cancer, France
RICHARDSON D. 2 , LEURAUD K. 3 , CARDIS E. 4 , DANIELS R. 5 , GILLIES M. 6 , O’HAGAN J. 6 , HAMRA G. 7 , HAYLOCK R. 6 , LAURIER D. 3 , MOISSONNIER M. 1 , SCHUBAUER-BERIGAN M. 5 , THIERRY-CHEF I. 1

1 Section of Environment and Radiation, International Agency for Research on Cancer, France
2 Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
3 Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM/SRBE/LEPID, Fontenay-aux-Roses, France
4 ISGlobal, Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain
5 National Institute for Occupational Safety and Health, Cincinnati, Ohio, USA
6 Public Health England Centre for Radiation, Chemical and Environmental Hazards (PHE-CRCE), Chilton, UK
7 Department of Environmental and Occupational Health, Drexel University School of Public Health, Philadelphia, P.A. USA

Purpose
The carcinogenic effects of ionising radiation (IR) have been studied for decades. While the moderate to high exposure effects are well characterized, the low-level, chronic exposure effects remain a subject of continued debate. An International Nuclear Workers Study (INWORKS) was therefore established to further improve the precision of estimates of cancer risk following protracted low doses of IR and to strengthen the scientific basis of radiation protection standards. 
Methods
INWORKS is built upon the previous 15-country study of nuclear industry workers and includes 308,297 workers with individual monitoring data for external exposure from France, the United Kingdom, and the United States of America. Excess relative rate (ERR) per gray (Gy) of radiation dose for mortality from cancer and haematological malignancies was estimated after ascertaining vital status and cause of death through linkage with national and regional death registries and other sources.
Results
We observed 66,632 deaths, including 17,957 deaths from solid cancers and 1,791 deaths from haematological cancers. Statistically significant associations were seen between red bone marrow dose and risk of leukaemia (excluding chronic lymphocytic leukaemia (CLL)), and between colon dose and risk of solid cancers. The ERR of non-CLL leukaemia mortality was 2.96 per Gy (90% CI 1.17–5.21) and for solid cancers - 0.47 per Gy (90% CI 0.18-0.79).
Conclusions
INWORKS provides some of the strongest evidence for an association between protracted low dose exposure to IR and cancer mortality. The risk per unit of dose in our study was similar to estimates derived from studies of Japanese atomic bomb survivors.
Funding source
Support from the US Centers for Disease Control and Prevention; Ministry of Health, Labour and Welfare of Japan; Institut de Radioprotection et de Sûreté Nucléaire; AREVA; Electricité de France; US National Institute for Occupational Safety and Health; US Department of Energy; and Public Health England.