Risk of cancer from occupational exposure to ionising radiation: retrospective cohort study of workers in France, the United Kingdom, and the United States (INWORKS).
OBJECTIVE
Is protracted exposure to low doses of ionising radiation associated with an increased risk of solid cancer?


METHODS
In this cohort study, 308,297 workers in the nuclear industry from France, the United Kingdom, and the United States with detailed monitoring data for external exposure to ionising radiation were linked to death registries. Excess relative rate per Gy of radiation dose for mortality from cancer was estimated. Follow-up encompassed 8.2 million person years. Of 66,632 known deaths by the end of follow-up, 17,957 were due to solid cancers.


CONCLUSIONS
Results suggest a linear increase in the rate of cancer with increasing radiation exposure. The average cumulative colon dose estimated among exposed workers was 20.9 mGy (median 4.1 mGy). The estimated rate of mortality from all cancers excluding leukaemia increased with cumulative dose by 48% per Gy (90% confidence interval 20% to 79%), lagged by 10 years. Similar associations were seen for mortality from all solid cancers (47% (18% to 79%)), and within each country. The estimated association over the dose range of 0-100 mGy was similar in magnitude to that obtained over the entire dose range but less precise. Smoking and occupational asbestos exposure are potential confounders; however, exclusion of deaths from lung cancer and pleural cancer did not affect the estimated association. Despite substantial efforts to characterise the performance of the radiation dosimeters used, the possibility of measurement error remains.


CONCLUSIONS
The study provides a direct estimate of the association between protracted low dose exposure to ionising radiation and solid cancer mortality. Although high dose rate exposures are thought to be more dangerous than low dose rate exposures, the risk per unit of radiation dose for cancer among radiation workers was similar to estimates derived from studies of Japanese atomic bomb survivors. Quantifying the cancer risks associated with protracted radiation exposures can help strengthen the foundation for radiation protection standards.


BACKGROUND
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. Data are maintained and kept at the International Agency for Research on Cancer.
Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, NC 27599, USA david.richardson@unc.edu.
David B
DB
Richardson
Center for Research in Environmental Epidemiology, Barcelona, Spain Universitat Pompeu Fabra, Barcelona, Spain CIBER Epidemiología y Salud Pública, Madrid, Spain.
Elisabeth
E
Cardis
National Institute for Occupational Safety and Health, Cincinnati, OH, USA.
Robert D
RD
Daniels
Public Health England Centre for Radiation, Chemical and Environmental Hazards, Chilton, UK.
Michael
M
Gillies
Public Health England Centre for Radiation, Chemical and Environmental Hazards, Chilton, UK.
Jacqueline A
JA
O'Hagan
Department of Environmental and Occupational Health, Drexel University School of Public Health, Philadelphia, PA, USA.
Ghassan B
GB
Hamra
Public Health England Centre for Radiation, Chemical and Environmental Hazards, Chilton, UK.
Richard
R
Haylock
Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France.
Dominique
D
Laurier
Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France.
Klervi
K
Leuraud
International Agency for Research on Cancer, Lyon, France.
Monika
M
Moissonnier
National Institute for Occupational Safety and Health, Cincinnati, OH, USA.
Mary K
MK
Schubauer-Berigan
International Agency for Research on Cancer, Lyon, France.
Isabelle
I
Thierry-Chef
International Agency for Research on Cancer, Lyon, France.
Ausrele
A
Kesminiene
D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007221:Industry; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D009784:Occupational Diseases; D016273:Occupational Exposure / Q000009:adverse effects*; D011829:Radiation Dosage; D011839:Radiation, Ionizing; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D006113:United Kingdom / Q000453:epidemiology; D014481:United States / Q000453:epidemiology