The effect of sunlight and UV lamps on EPR signal in nails

Abstract

The effects of illumination of nail clippings by direct sunlight, UV lamps and fluorescent bulbs on native and radiationinduced electron paramagnetic resonance (EPR) signals in nails are presented. It is shown that a few minutes of exposure of the nail clippings to light including a UV component (sunlight and UV lamps) generates a strong EPR signal similar to the other EPR signals observable in nails: native background (BKG), mechanically induced (MIS) or radiation-induced (RIS). This effect was observed in clippings exposed and unexposed to ionizing radiation prior to the light illuminations. An exposure of the clippings to fluorescent light without a UV component generated, within the examined range of the light fluences (up to 240 kJ/m 2), an EPR signal with considerably lower yield than UV light. The light-induced signal (LIS) decayed after 10 min of water treatment of the samples. In contrast, it was still observable 3 months after illumination in samples stored in air at room temperature, and 3 weeks in frozen samples, respectively. It is concluded that the LIS can considerably affect assessment of the dosimetric RIS components in irradiated nails, and of the background signals in unirradiated nails, thus contributing to errors in EPR dosimetry in nails.

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

“…7 b). A lack of any effect of visible light on the EPR signal was also reported by Marciniak et al ( 2019 ) for nails clippings—in their study, the light without any UV component had no effect on the nails’ EPR signal, in contrast to light including a UV component. For the iP1_6S_10Gy sample, the RIS stabilized after the initial light-induced decay and maintained its magnitude about 45 days at about 50% of its value measured shortly after illumination (Fig.…”

“…7b). A lack of any effect of visible light on the EPR signal was also reported by Marciniak et al (2019) for nails clippings-in their study, the light without any UV component had no effect on the nails' EPR signal, in contrast Fig. 7 a EPR spectra of the iPhone 6S sample-their background signal (BG), 10 Gy RIS and the spectra after exposure to X-rays to a dose of 10 Gy dose, and after illumination by the CLEO UV lamp (for data point marked in b by the filled diamond).…”

“…Sensitivity to light was also proven for other materials used in EPR dosimetry like alanine, where visible light causes fading of radiationinduced radicals, a change in the shape of the spectra, and a decrease in magnitude of the dosimetric signal (Ciesielski et al 2004(Ciesielski et al , 2008. Also in human nails, generation of a strong EPR signal, similar to the radiation-induced signal, by the UV component of light was recently reported by Marciniak et al (2019).…”

Time evolution of radiation-induced EPR signals in different types of mobile phone screen glasses

“…However, their applicability is limited due to the obvious difficulty in sample acquisition. Initial studies on EPR dosimetry in nail clippings indicated potential large inaccuracies in reconstructed doses, due to the presence of confounding EPR signals generated mechanically in the samples by cutting, and due to the fading of the dosimetric signal caused by exposure of nails to water (Trompier et al 2009a; Marciniak et al 2018) or induction of obscuring EPR signals by light (Sholom et al 2018; Marciniak et al 2019). Therefore, artificial materials in the vicinity of exposed individuals as well as personal belongings could provide better dosimetric materials more convenient in usage, provided that they preserve any radiation-induced EPR signals.…”