Risk of Cancer Associated with Low Dose Radiation Exposure: Comparison of Results between the INWORKS nuclear workers study and the A-bomb Survivors Study

International audience ; The Life Span Study (LSS) of Japanese atomic bomb survivors has served as the primary basis for estimates of radiation-related disease risks that inform radiation protection standards. The long-term follow-up of radiation monitored nuclear workers provides estimates of radiation-cancer associations that complement findings from the LSS. We present a comparison of radiation-cancer mortality risk estimates derived from the LSS and INWORKS, a large international nuclear worker study. Restrictions were made so that the two study populations are similar with respect to ages and periods of exposure, leading to selecting 45,625 A-bomb survivors and 259,350 nuclear workers. For solid cancer, excess relative rates (ERR) per gray (Gy) were 0.28 (90% CI 0.18; 0.38) in the LSS and 0.29 (90% CI 0.07; 0.53) in INWORKS, with minimal evidence of curvature or of a modifying effect of attained age, age at exposure, or sex in either study. There was evidence in both cohorts of modification of the excess absolute risk (EAR) of solid cancer by attained age, with a trend of increasing EAR per Gy with attained age. For leukemia, the ERR per Gy was 2.75 (90% CI 1.73; 4.21) in the LSS and 3.15 (90% CI 1.12; 5.72) in INWORKS, while the EAR per Gy was 3.54 (90% CI 2.30; 5.05) in the LSS and 2.03 (90% CI 0.36; 4.07) in INWORKS. These findings from different study populations may help inform understanding of radiation risks, with INWORKS contributing information derived from the study of workers with protracted low dose rate exposures.