Leukaemia, lymphoma, and multiple myeloma mortality after low-level exposure to ionising radiation in nuclear workers (INWORKS): updated findings from an international cohort study

In a new article, researchers from the International Agency for Research on Cancer (IARC) and partner institutions in France, Spain, the United Kingdom, and the USA who are studying the effects of persistent exposure to low doses of ionizing radiation on workers in nuclear facilities report an increase in mortality due to haematological neoplasms. The findings were published in The Lancet Haematology.

The scientists found a positive association between long-term low-dose exposure to ionizing radiation and mortality due to leukaemia (excluding chronic lymphocytic leukaemia [CLL]), chronic myeloid leukaemia, acute myeloid leukaemia, myelodysplastic syndrome, and multiple myeloma.

The scientists estimated that the mortality rate due to leukaemia increased by more than 250% per gray (Gy) of exposure (excess relative rate [ERR] per Gy, 2.68; 90% confidence interval, 1.13–4.55) and found the excess rate to be reasonably described by a linear dose–response model. The dose of radiation exposure typically accrued by workers in the study was low, at 0.016 Gy, and absolute mortality from leukaemia attributable to radiation exposure in the study population was estimated at 13 excess deaths per 100 000 workers over a period of 35 years (compared with 250 deaths expected from non-CLL leukaemia among those unexposed to radiation). A gray is a unit of the radiation quantity absorbed dose that measures the energy deposited by ionizing radiation, defined as the absorption of one joule of radiation energy per kilogram of matter.

Studies of people exposed to low doses of radiation add to our understanding of radiation risks at the exposure levels of contemporary concern, and thus can inform radiation protection efforts. The ERR per Gy for leukaemia mortality estimated in this study is close to the excess rate previously estimated in the Radiation Effects Research Foundation Life Span Study of Japanese atomic bomb survivors, which was 2.75 per Gy.

This new article is a major update to the International Nuclear Workers Study (INWORKS), which followed up 309 932 workers in the nuclear industry for an average of nearly 35 years, resulting in a total follow-up of 10.7 million person-years. The workers were employed at nuclear sites in France, the United Kingdom, and the USA and were monitored with radiation badges, which measured their exposure to radiation.

IARC has been coordinating and leading pooled studies of nuclear workers for more than 35 years. The INWORKS study partners are IARC, the Institut de Radioprotection et de Sûreté Nucléaire (France), the UK Health Security Agency, the National Institute for Occupational Safety and Health (USA), the Instituto de Salud Global de Barcelona (Spain), and the University of California, Irvine Joe C. Wen School of Population & Public Health (USA).

Leuraud K, Laurier D, Gillies M, Haylock R, Kelly-Reif K, Bertke S, et al.
Leukaemia, lymphoma, and multiple myeloma mortality after low-level exposure to ionising radiation in nuclear workers (INWORKS): updated findings from an international cohort study
Lancet Haematol, Published online 30 August 2024;
https://doi.org/10.1016/S2352-3026(24)00240-0

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Read “Cancer mortality after low dose exposure to ionising radiation in workers in France, the United Kingdom, and the United States (INWORKS): cohort study”, a related article describing the association between exposure to ionizing radiation and mortality due to solid cancers