Effect of heating on the ESR signal of human fingernails

The potential confounding influence of heat on the electron spin resonance (ESR) spectra of fingernails has been studied in irradiated and unirradiated samples. The samples were heated at different temperatures between 20 and 160 ? for 1 h. The experimental temperature range was selected considering that the fingernails may be accidentally exposed to heat during normal daily activities or in a certain working environment. Changes in the overall visual shape of the ESR spectra were observed in the gamma-ray irradiated and unirradiated samples heated above 100 ?, thereby showing that a heat-induced signal was present in the fingernail spectrum. The effect of heating showed an evident bulge in the spectra (between g = 2.014 and 2.024), which was more pronounced in both the irradiated and unirradiated samples heated at higher temperatures, with reduced peak-to-peak intensities and broadened spectra. The heat-induced signal was unstable, decayed for about a few days, and was easily removed upon treatment with water. While the radiation-induced signal (RIS) was stable up to 160 ?, our results also suggest that heating up to 160 ? did not affect the sensitivity of the RIS, but the heat-induced signal was still observed after irradiation. Similar thermal stability was also found in both the irradiated and unirradiated samples, suggesting that the heat-induced signal and RIS were overlapped, but probably independent. Overall, these findings will be useful to obtain a more reliable radiation dose assessment using fingernails that

Automated summary

The study found that heat influences the ESR spectra of fingernails, leading to changes in the spectra's visual shape when heated above 100?. The heat-induced signal decays within a few days and can be easily removed with water, while the radiation-induced signal remains stable up to 160?. The heat-induced signal and radiation-induced signal in the fingernail spectra may overlap but are likely independent of each other.