Low dose ionizing radiation produces too few reactive oxygen species to directly affect antioxidant concentrations in cells

Abstract

It has been hypothesized that radiation-induced oxidative stress is the mechanism for a wide range of negative impacts on biota living in radioactively contaminated areas around Chernobyl. The present study tests this hypothesis mechanistically, for the first time, by modelling the impacts of radiolysis products within the cell resulting from radiations (low linear energy transfer β and γ), and dose rates appropriate to current contamination types and densities in the Chernobyl exclusion zone and at Fukushima. At 417 µGy h(-1) (illustrative of the most contaminated areas at Chernobyl), generation of radiolysis products did not significantly impact cellular concentrations of reactive oxygen species, or cellular redox potential. This study does not support the hypothesis that direct oxidizing stress is a mechanism for damage to organisms exposed to chronic radiation at dose rates typical of contaminated environments.

Figure 1.

Changes in (a) α-tocopherol and (b) carotenoids in birds' liver as a result of 417 µGy h⁻¹ ionizing radiation (many times higher than the mean at the Chernobyl study sites; see electronic supplementary material). (Anti-oxidant concentrations were estimated from Møller et al. [4].)

Figure 2.

Predicted changes in glutathione (GSH) concentration (dashed line) and cellular redox potential (E_h) following 1200 day exposure to 10 mGy d⁻¹ (417 µGy h⁻¹) ionizing radiation assuming initial 1 mM total (GSH + GSSG) and an unrealistically slow glutathione replenishment rate of 0.001 d⁻¹. Solid line, E_h (mV).