###### Abstract  
The effects of L(+)-ascorbic acid (AA) (an antioxidant commonly known as vitamin C) on the electron spin resonance (ESR) signals from fingernails were examined in relation to X-ray and UV irradiation. The ESR signal intensity, stability, and sensitivity to radiation were measured under different storage conditions. The experimental results indicated that the behavior of the increase in the ESR intensity of the AA samples varied depending on the storage and location conditions, showing sensitivity to light and signal instability at room temperature. It was found that the AA treatment caused a large increase in the peak-to-peak intensities with continuous signal growth with storage time, which may provide an enhancement to the radiation-dependent signal in fingernails. It was also suggested that the use of AA for pre-treatment could sufficiently remove the disturbing signals induced by heat or UV light exposure, which is expected to improve the reliability of radiation dosimetry using fingernails. Further studies with different antioxidant conditions are needed to better characterize the complex changes of the ESR signals from fingernails.  
radiological accident; retrospective dosimetry; ESR; EPR; fingernails; antioxidants; ascorbic acid +
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provide a clear view of the positive influence of these treatments because not only BGS can be reduced in the spectrum but also the RIS intensity. Moreover, the use of DTT reducing agent for chemical treatment may provide toxicological effects when handling is not properly managed. With these challenges concerning the BGS, an effort to identify its possible nature or origin has been given attention in a more recent study [11]. The authors of the study advanced that common radicals (i.e., o-semiquinone) are responsible for the RIS and BGS: the RIS being produced from exposure to ionizing radiation and the BGS from UV effects, and thus both signals are characterized to be virtually and chemically identical [11]. This hypothesis has led to a suggestion that chemical treatment methods using oxidizing (0.1 M potassium ferricanide) or reducing (0.1 M DTT) agents are unlikely to yield the potentials to discriminate the RIS and BGS [11]. On the other hand, given the limited published research literature to date, further studies are expected to investigate the interactions of various chemicals such as antioxidants on quenching free radicals. Moreover, as UV exposure has the effect of generating a strong ESR signal [1] and that the BGS is surmised to be produced by the UV effects [11], it is also a good opportunity to test the use of such antioxidants to reduce UV-related exposures which could occur during daily activities but are not well considered yet.  
The aim of our study was to investigate the application of a non-hazardous chemical that can work as a natural antioxidant and scavenger of free radicals. The current work focused on the use of L(+)-ascorbic acid (hereafter \"AA\"), known as vitamin C, and examined the effects of AA treatment on the ESR signals of unirradiated and irradiated fingernails (i.e., X-ray and UV irradiation). It is anticipated that the AA may react vigorously to ambient conditions and, therefore, the influence of AA on the ESR signals of fingernails was demonstrated using two different storage mediums (vacuum and non-vacuum) under a variety of location conditions. The effects of the AA treatment were analyzed based on the signal stability and sensitivity change before and after the treatment or irradiation.