Occupational radiation exposure and risk of cataract incidence in a cohort of US radiologic technologists
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It has long been known that relatively high-dose ionising radiation exposure (> 1 Gy) can induce cataract, but there has been no evidence that this occurs at low doses (< 100 mGy). To assess low-dose risk, participants from the US Radiologic Technologists Study, a large, prospective cohort, were followed from date of mailed questionnaire survey completed during 1994–1998 to the earliest of self-reported diagnosis of cataract/cataract surgery, cancer other than non-melanoma skin, or date of last survey (up to end 2014). Cox proportional hazards models with age as timescale were used, adjusted for a priori selected cataract risk factors (diabetes, body mass index, smoking history, race, sex, birth year, cumulative UVB radiant exposure). 12,336 out of 67,246 eligible technologists reported a history of diagnosis of cataract during 832,479 person years of follow-up, and 5509 from 67,709 eligible technologists reported undergoing cataract surgery with 888,420 person years of follow-up. The mean cumulative estimated 5-year lagged eye-lens absorbed dose from occupational radiation exposures was 55.7 mGy (interquartile range 23.6–69.0 mGy). Five-year lagged occupational radiation exposure was strongly associated with self-reported cataract, with an excess hazard ratio/mGy of 0.69 × 10−3 (95% CI 0.27 × 10−3 to 1.16 × 10−3, p < 0.001). Cataract risk remained statistically significant (p = 0.030) when analysis was restricted to < 100 mGy cumulative occupational radiation exposure to the eye lens. A non-significantly increased excess hazard ratio/mGy of 0.34 × 10−3 (95% CI − 0.19 × 10−3 to 0.97 × 10−3, p = 0.221) was observed for cataract surgery. Our results suggest that there is excess risk for cataract associated with radiation exposure from low-dose and low dose-rate occupational exposures.
KeywordsIonising radiation Cataract Cataract surgery Threshold Tissue reaction effects Diabetes Low dose rate Questionnaire-based assessment
The authors thank the two referees for their detailed and helpful comments. The authors thank the radiologic technologists who participated in the study, Dr. Jerry Reid of the American Registry of Radiologic Technologists for continued support, and Diane Kampa and Allison Iwan of the University of Minnesota for study management and data collection.
MPL, CMK and MSL conceived and designed the study, and produced an analytical plan. MSL, MMD, BHA, MPL and JSM were responsible for acquisition and processing of data (including questionnaire, mortality, and cancer validation data). SLS, DLP, MMD, JSM, MSL, BHA, MPL and DB were responsible for dose estimation and validation. MPL was responsible for data analysis. MPL, CMK, MSL, DB, NH and CM interpreted the results. MPL produced a first draft of the manuscript. All authors reviewed the manuscript and provided intellectual input. MPL, CMK and MSL are guarantors.
This work was funded by the Intramural Research Program of the Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health. CM was supported by a training grant from Midwest Center for Occupational Safety and Health CDC/NIOSH 2T42 OH008434. The views expressed herein by the authors are independent of all funding agencies.
Compliance with ethical standards
Conflict of interest
All authors declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous 3 years; and no other relationships or activities that could appear to have influenced the submitted work.
The data and all code used for the analysis are available from the lead author on application.
This study has been approved annually by the National Cancer Institute Special Studies Institution Review Board and by the University of Minnesota Institutional Review Board.
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