BACKGROUND: There is much uncertainty about the risks of leukaemia and lymphoma 
after repeated or protracted low-dose radiation exposure typical of 
occupational, environmental, and diagnostic medical settings. We quantified 
associations between protracted low-dose radiation exposures and leukaemia, 
lymphoma, and multiple myeloma mortality among radiation-monitored adults 
employed in France, the UK, and the USA.
METHODS: We assembled a cohort of 308,297 radiation-monitored workers employed 
for at least 1 year by the Atomic Energy Commission, AREVA Nuclear Cycle, or the 
National Electricity Company in France, the Departments of Energy and Defence in 
the USA, and nuclear industry employers included in the National Registry for 
Radiation Workers in the UK. The cohort was followed up for a total of 8.22 
million person-years. We ascertained deaths caused by leukaemia, lymphoma, and 
multiple myeloma. We used Poisson regression to quantify associations between 
estimated red bone marrow absorbed dose and leukaemia and lymphoma mortality.
FINDINGS: Doses were accrued at very low rates (mean 1.1 mGy per year, SD 2.6). 
The excess relative risk of leukaemia mortality (excluding chronic lymphocytic 
leukaemia) was 2.96 per Gy (90% CI 1.17-5.21; lagged 2 years), most notably 
because of an association between radiation dose and mortality from chronic 
myeloid leukaemia (excess relative risk per Gy 10.45, 90% CI 4.48-19.65).
INTERPRETATION: This study provides strong evidence of positive associations 
between protracted low-dose radiation exposure and leukaemia.
FUNDING: 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, National Institute for Occupational Safety and Health, US 
Department of Energy, US Department of Health and Human Services, University of 
North Carolina, Public Health England.