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Original research
Occupational radiation exposure and excess additive risk of cataract incidence in a cohort of US radiologic technologists
  1. Mark P Little1,
  2. Elizabeth K Cahoon1,
  3. Cari M Kitahara1,
  4. Steven L Simon2,
  5. Nobuyuki Hamada3,
  6. Martha S Linet1
  1. 1 Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, USA
  2. 2 Epidemiology and Biostatistics Program, NCI, Bethesda, Maryland, USA
  3. 3 Radiation Safety Research Center, Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), Tokyo, Japan
  1. Correspondence to Dr Mark P Little, Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD 20892, USA; mark.little{at}


Objectives Previous analyses of cataract in radiation-exposed populations have assessed relative risk; radiogenic excess additive risk (EAR), arguably of more public health importance, has not been estimated. Previous analysis of a large prospective cohort of US radiologic technologists (USRT) quantified excess relative risk of cataract in relation to occupational radiation dose. We aim to assess EARs of cataract.

Methods We estimated EARs of cataract/cataract surgery in the USRT cohort using generalised additive models in relation to occupational radiation exposure, and assessed risk modification by a priori-selected cataract risk factors (diabetes, body mass index, smoking, race, sex, birth-year, ultraviolet B (UVB) radiation exposure).

Results There were 11 345 cataract diagnoses and 5440 of cataract surgery during 832 462 and 888 402 person-years of follow-up, respectively. Cumulative occupational radiation exposure was associated with self-reported cataract, but not with cataract surgery, with EAR/104 person-year Gy=94 (95% CI: 47 to 143, p<0.001) and EAR/104 person-year Gy=13 (95% CI: <0 to 57, p=0.551), respectively. There was marked (p<0.001) variation of EAR by age and by diabetes status, with risk higher among persons ≥75 years and diabetics. There were indications of elevated risk among those with higher UVB radiation (p=0.045), whites (p=0.056) and among those with higher levels of cigarette smoking (p=0.062). Elevated additive risk was observed for estimated occupational radiation eye-lens doses <100 mGy (p=0.004) with no dose–response curvature (p=0.903).

Conclusions The elevated additive risks associated with low-dose radiation, if confirmed elsewhere, have important public health and clinical implications for radiation workers as well as regulatory measures.

  • ophthalmology
  • public health
  • diabetes mellitus
  • visual defects
  • ionising radiation

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  • Contributors MPL, CMK, EKC, SLS and MSL conceived and designed the study, and produced an analytical plan. MSL and MPL were responsible for acquisition and processing of data (including questionnaire, mortality and cancer validation data). SLS, MSL and MPL were responsible for dose estimation and validation. MPL was responsible for data analysis. MPL, NH, MSL, CMK and EKC interpreted the results. MPL produced a first draft of the manuscript. All authors reviewed the manuscript and provided intellectual input. MPL, CMK, EKC and MSL are guarantors.

  • Funding This work was funded by the Intramural Research Program of the Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health. The views expressed herein by the authors are independent of all funding agencies.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval This study has been approved annually by the National Cancer Institute Special Studies Institutional Review Board and by the University of Minnesota Institutional Review Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon request.