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Norman J Kleiman, Anton Lavrinienko, Kati Kivisaari, Zbyszek Boratynski, Lawrence Dauer, Tapio Mappes, Tim Mousseau; Radiation Cataract in Chernobyl Voles. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2037.
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© ARVO (1962-2015); The Authors (2016-present)
The lens of the eye is one of the most radiosensitive tissues in the body and exposure is associated with cataract. Severity and latency are related to dose. New human exposure guidelines suggest a 7 fold lower human radiation cataract threshold.The 1986 Chernobyl Nuclear Power Plant (NPP) accident caused radioactive contamination in parts of Ukraine, Belarus and Russia and establishment of a 30 km radius “exclusion zone”. 30 years later, despite extensive cleanup and remediation, surrounding areas remains heavily contaminated. Surprisingly, ocular studies in nearby animal populations are limited. We hypothesized that bank voles (Myodes glareolus) living in highly radioactive soil will have significant lens changes consistent with radiation exposure.
Comprehensive physical and dilated slit lamp examinations were made in ~175 voles trapped from 60 locations surrounding the NPP. Whole body gamma counts provided estimates of internal dose and ground-based measurements average external dose. Individual lens dose was estimated using a phantom and Monte Carlo calculations. Radiation-associated lens changes were quantified by modified Merriam-Focht (M-F) scoring criteria.
Physical examination indicated voles were quite young; most less than 9 months old. External doses ranged from 0.18 to >120 µSv/hr. Internal doses ranged from 10 to >5,000 cpm. Voles in the highest exposure quartile had significantly higher average M-F cataract scores (p<0.03) than those in lower quartiles. Estimates of eye dose ranged up to 500 mSv/yr.Because older voles or those with visual disability were likely eliminated from wild populations, voles originally trapped in the Chernobyl region but maintained at Kiev University for >18 months were also examined. A 75% prevalence of radiation associated lens changes was noted as compared to <10% for similarly aged control animals.
This study is the first report of dilated slit lamp findings in any Chernobyl animal population. In contrast to studies claiming no major detrimental exposure effects in Chernobyl wildlife, a significant relationship between dose and radiation-associated lens changes was observed. These results are consistent with human studies that support radiation cataract development after relatively low environmental exposures. The findings support closer scrutiny of the relationship between acute and chronic radiation dose and cataract formation in both humans and other mammals.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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