Ionizing radiation and risk of chronic lymphocytic leukemia in the 15-country study of nuclear industry workers.
In contrast to other types of leukemia, chronic lymphocytic leukemia (CLL) has long been regarded as non-radiogenic, i.e. not caused by ionizing radiation. However, the justification for this view has been challenged. We therefore report on the relationship between CLL mortality and external ionizing radiation dose within the 15-country nuclear workers cohort study. The analyses included, in seven countries with CLL deaths, a total of 295,963 workers with more than 4.5 million person-years of follow-up and an average cumulative bone marrow dose of 15 mSv; there were 65 CLL deaths in this cohort. The relative risk (RR) at an occupational dose of 100 mSv compared to 0 mSv was 0.84 (95% CI 0.39, 1.48) under the assumption of a 10-year exposure lag. Analyses of longer lag periods showed little variation in the RR, but they included very small numbers of cases with relatively high doses. In conclusion, the largest nuclear workers cohort study to date finds little evidence for an association between low doses of external ionizing radiation and CLL mortality. This study had little power due to low doses, short follow-up periods, and uncertainties in CLL ascertainment from death certificates; an extended follow-up of the cohorts is merited and would ideally include incident cancer cases.
Vrijheid
Martine
M
International Agency for Research on Cancer, Lyon, France. mvrijheid@creal.cat
Cardis
Elisabeth
E
Ashmore
Patrick
P
Auvinen
Anssi
A
Gilbert
Ethel
E
Habib
Rima R
RR
Malker
Hans
H
Muirhead
Colin R
CR
Richardson
David B
DB
Rogel
Agnes
A
Schubauer-Berigan
Mary
M
Tardy
Hélène
H
Telle-Lamberton
Maylis
M
D015331:Cohort Studies; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000209:etiology*; D007953:Leukemia, Radiation-Induced / Q000209:etiology*; D055848:Nuclear Power Plants; D009784:Occupational Diseases / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors