Risk of cancer associated with low-dose radiation exposure: comparison of results between the INWORKS nuclear workers study and the A-bomb survivors study

Abstract

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. Here, a comparison of radiation-cancer mortality risk estimates derived from the LSS and INWORKS, a large international nuclear worker study, is presented. Restrictions were made, so that the two study populations were similar with respect to ages and periods of exposure, leading to selection of 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. A joint analysis of the data allowed for a formal assessment of heterogeneity of the ERR per Gy across the two studies (P = 0.909), 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, under a simple linear model, 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, with evidence of curvature in the association across the range of dose observed in the LSS but not in INWORKS; 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 understanding of radiation risks, with INWORKS contributing information derived from cohorts of workers with protracted low dose-rate exposures.

Perturbed transcriptional profiles after chronic low dose rate radiation in mice

“…Insights into molecular events initiated by exposure to different dose rates can give valuable contributions to the ongoing debate regarding the relevance of the dose rate upon cellular responses and health outcomes of ionizing radiation [ 24 , 32 , 56 ]. Our study shows that hepatic transcriptional profiles are modulated dose-rate-specific in response to whole-body exposure to an equal total dose gamma irradiation, given at low, medium, and high dose rates, chronic to acute.…”

Areas of research to support the system of radiological protection

“…In contrast, except in the medical field, radiological protection is generally concerned with exposure situations involving lower doses and dose rates, even if cumulated doses over 100 mGy may be encountered in specific situations. The question of whether low dose-rate exposures are less carcinogenic than high dose-rate exposures, given the same dose, remains controversial (Rühm et al 2016 ; Shore et al 2017 ; Leuraud et al 2021 ). Therefore, research on the dose-rate dependence of cancer risk continues to be important, with a focus on epidemiological studies among human cohorts, backed by radiobiological studies on the mechanisms of cancer development.…”

DNA Damage Response of Haematopoietic Stem and Progenitor Cells to High-LET Neutron Irradiation

“…In addition to these epidemiological studies on the mainly high and acute IR exposures during the atomic bombs, several studies have also linked low-dose IR exposures to increased leukaemia risks. Examples are the elevated risk to develop leukaemia after diagnostic CT scans during childhood, as well as the large international nuclear worker study (INWORKS), where repeated and protracted low-dose IR exposures were associated with an elevated leukaemia risk [11][12][13][14][15][16] .…”