title: Radiation and the risk of chronic lymphocytic and other leukemias among chornobyl cleanup workers.
abstract: BACKGROUND
  Risks of most types of leukemia from exposure to acute high doses of ionizing radiation are well known, but risks associated with protracted exposures, as well as associations between radiation and chronic lymphocytic leukemia (CLL), are not clear.
  
  
  OBJECTIVE
  We estimated relative risks of CLL and non-CLL from protracted exposures to low-dose ionizing radiation.
  
  
  METHODS
  A nested case-control study was conducted in a cohort of 110,645 Ukrainian cleanup workers of the 1986 Chornobyl nuclear power plant accident. Cases of incident leukemia diagnosed in 1986-2006 were confirmed by a panel of expert hematologists/hematopathologists. Controls were matched to cases on place of residence and year of birth. We estimated individual bone marrow radiation doses by the Realistic Analytical Dose Reconstruction with Uncertainty Estimation (RADRUE) method. We then used a conditional logistic regression model to estimate excess relative risk of leukemia per gray (ERR/Gy) of radiation dose.
  
  
  RESULTS
  We found a significant linear dose response for all leukemia [137 cases, ERR/Gy = 1.26 (95% CI: 0.03, 3.58]. There were nonsignificant positive dose responses for both CLL and non-CLL (ERR/Gy = 0.76 and 1.87, respectively). In our primary analysis excluding 20 cases with direct in-person interviews < 2 years from start of chemotherapy with an anomalous finding of ERR/Gy = -0.47 (95% CI: < -0.47, 1.02), the ERR/Gy for the remaining 117 cases was 2.38 (95% CI: 0.49, 5.87). For CLL, the ERR/Gy was 2.58 (95% CI: 0.02, 8.43), and for non-CLL, ERR/Gy was 2.21 (95% CI: 0.05, 7.61). Altogether, 16% of leukemia cases (18% of CLL, 15% of non-CLL) were attributed to radiation exposure.
  
  
  CONCLUSIONS
  Exposure to low doses and to low dose-rates of radiation from post-Chornobyl cleanup work was associated with a significant increase in risk of leukemia, which was statistically consistent with estimates for the Japanese atomic bomb survivors. Based on the primary analysis, we conclude that CLL and non-CLL are both radiosensitive.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Medicine, University of California, San Francisco, San Francisco, California 94118, USA. lydia.zablotska@ucsf.edu
authors.forename: Lydia B
authors.initials: LB
authors.lastname: Zablotska
authors.forename: Dimitry
authors.initials: D
authors.lastname: Bazyka
authors.forename: Jay H
authors.initials: JH
authors.lastname: Lubin
authors.forename: Nataliya
authors.initials: N
authors.lastname: Gudzenko
authors.forename: Mark P
authors.initials: MP
authors.lastname: Little
authors.forename: Maureen
authors.initials: M
authors.lastname: Hatch
authors.forename: Stuart
authors.initials: S
authors.lastname: Finch
authors.forename: Irina
authors.initials: I
authors.lastname: Dyagil
authors.forename: Robert F
authors.initials: RF
authors.lastname: Reiss
authors.forename: Vadim V
authors.initials: VV
authors.lastname: Chumak
authors.forename: Andre
authors.initials: A
authors.lastname: Bouville
authors.forename: Vladimir
authors.initials: V
authors.lastname: Drozdovitch
authors.forename: Victor P
authors.initials: VP
authors.lastname: Kryuchkov
authors.forename: Ivan
authors.initials: I
authors.lastname: Golovanov
authors.forename: Elena
authors.initials: E
authors.lastname: Bakhanova
authors.forename: Nataliya
authors.initials: N
authors.lastname: Babkina
authors.forename: Tatiana
authors.initials: T
authors.lastname: Lubarets
authors.forename: Volodymyr
authors.initials: V
authors.lastname: Bebeshko
authors.forename: Anatoly
authors.initials: A
authors.lastname: Romanenko
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Mabuchi
mesh_terms: D016022:Case-Control Studies; D047852:Chernobyl Nuclear Accident; D006801:Humans; D007953:Leukemia, Radiation-Induced / Q000453:epidemiology*; D008214:Lymphocytes / Q000528:radiation effects; D016273:Occupational Exposure / Q000009:adverse effects*; D011839:Radiation, Ionizing