The effect of sunlight and UV lamp exposure on EPR signals in X-ray irradiated touch screens of mobile phones

Abstract

Electron paramagnetic resonance (EPR) signals generated by ionizing radiation in touch-screen glasses have been reported as useful for personal dosimetry in people accidently exposed to ionizing radiation. This article describes the effect of light exposure on EPR spectra of various glasses obtained from mobile phones. This effect can lead to significant inaccuracy of the radiation doses reconstructed by EPR. The EPR signals from samples unexposed and exposed to X-rays and/or to natural and artificial light were numerically separated into three model spectra: those due to background (BG), radiation-induced signal (RIS), and light-induced signal (LIS). Although prolonged exposures of mobile phones to UV light are rather implausible, the article indicates errors underestimating the actual radiation doses in dose reconstruction in glasses exposed to UV light even for low fluences equivalent to several minutes of sunshine, if one neglects the effects of light in applied dosimetric procedures. About 5 min of exposure to sunlight or to light from common UV lamps reduced the intensity of the dosimetric spectral components by 20-60% as compared to non-illuminated samples. This effect strongly limits the achievable accuracy of retrospective dosimetry using EPR in glasses from mobile phones, unless their exposure to light containing a UV component can be excluded or the light-induced reduction in intensity of the RIS can be quantitatively estimated. A method for determination of a correction factor accounting for the perturbing light effects is proposed on basis of the determined relation between the dosimetric signal and intensity of the light-induced signal.

Comparison of three methods of EPR retrospective dosimetry in watch glass

“…Applicability of this method for other types of glasses requires verification of the background stability at high temperature. Moreover, as it results from previous reports ( 24 , 25 ), an important factor disturbing a reliable dose reconstruction in glasses may be the effect of UV light. Therefore, additional research is necessary to assess applicability of the annealing in EPR dosimetry in glasses exposed to UV light.…”

Sustainable Bioplastic Made from Biomass DNA and Ionomers

“…42 Moreover, the radiation intensity was 10 000 times higher than that from sunlight. 43 Within 40 min, shape deformation and rigidity change were not observed, demonstrating the good durability of DNA plastics under UV radiation (Figure S5C). The enhanced resistance to UV radiation was probably derived from two aspects: (1) ionomers provided protection for biomass DNA;…”

“…The radiation intensity was 1.5 W/cm 2 , which was strong enough to destroy DNA structures in solutions . Moreover, the radiation intensity was 10 000 times higher than that from sunlight . Within 40 min, shape deformation and rigidity change were not observed, demonstrating the good durability of DNA plastics under UV radiation (Figure S5C).…”