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Occupational Exposure to Low-dose Ionizing Radiation Increases Risk of Cataract

Posted on October 22, 2018

Investigators in the Radiation Epidemiology Branch (REB) have identified a significant exposure-response between low-dose cumulative occupational radiation exposure to the eye lens and risk of cataracts, based on self-reported history. The findings were published online August 27, 2018 in the journal European Journal of Epidemiology.

Prior to this study, it was long known that relatively high-dose exposure to ionizing radiation (greater than 0.5 Gy) can induce cataract, but there was no evidence for risk at low doses (conventionally under 100 mGy). To assess low-dose risk, REB investigators evaluated cataract and cataract surgery reported by participants from the large, prospective cohort, US Radiologic Technologists Study. Over 12,000 eligible technologists reported a history of diagnosis of cataract during over 830,000 person-years of follow-up; over 5,500 reported undergoing cataract surgery over a similar follow-up period. The results were adjusted for most of the standard cataract risk factors, including age, body mass index, diabetes, smoking, and cumulative exposure to ultraviolet radiation. Cumulative occupational radiation dose to the eye lens was associated with increased risk of cataract in this cohort, even at low doses (less than 100 mGy). This finding challenges the expert opinion of national and international review committees regarding the threshold dose for cataract formation, and further raises the question of whether such a threshold exists.

This report provides an update to a prior analysis by REB researchers of the same cohort. This time, the investigators had an additional nine years of data, and a more sophisticated, improved dosimetry.

Reference: Little MP, Kitahara CM, Cahoon EK, et al. Occupational radiation exposure and risk of cataract incidence in a cohort of US radiologic technologists. Eur J Epidemiol. 2018 Aug 27. doi: 10.1007/s10654-018-0435-3. [Epub ahead of print]