Investigation of the potential use of biological samples containing keratin as a dosimeter in various types and energies radiation exposure

Today with the increased exposure to non-ionizing radiation with mobile phones and base stations and to ionizing radiation with nuclear energy and medical applications, the determination of persons? absorbed radiation are of vital importance. Therefore, in our study, 900 MHz mobile phone radiation and Co-60 Cs-137 gamma radiation-exposed hair root and hair strand samples? potentials as a material for biological dosimetry were investigated by ESR and the Comet assay techniques.Non-ionizing radiation exposure was planned to imitate the use of mobile phones in daily life. The used mobile phone have operating frequency of 900 MHz GSM, the maximum absorption value of the power of 2 W and 0,974 W/kg human head SAR value specified by the manufacturer. Volunteers (8 subjects) spoke with the mobile phone for 15 and 30 minutes.Before and after exposure, each subject gave hair root samples plucked from behind the right ear (on which the mobile phone was used). These samples were used to detect possible DNA single strand breaks depend on the mobile phone talking time by comet assay technique. The tail length, tail moment values were determined from obtained images and the dose-response curves generated. The results showed that compare to before exposure, 15 and 30 minutes exposure to 900-MHz mobile phone radiation caused DNA single-strand breaks in human hair root cells located around the ear which is used for the phone calls. Comparing the 15-min and 30-min data using the paired t-test also showed that highly significantly more damages resulted after 30 minutes than after 15 minutes of phone use (p< .001). In addition, hair samples from subjects without cell phone exposure taken 5 and 15 min apart had been analyzed and found no significant difference compare to controls. Therefore, the changes after cell phone exposure were not caused by the process of hair removal, such as skin irritation. In the literature, there are no studies in which comet assay technique applied to the hair roots. In this sense in the present investigation for the first time, comet technique has been modified for hair root cells. As a result of series experiment, the conditions in which the most clear and adequate of the cell images could be get were determined as delayed hair root cells for 30 minutes in 0.03 ml solution.To evaluate the dosimetric potential for exposure case to ionizing radiation, the hair roots irradiated with Cs-137 source. 5 volunteers gave hair samples plucked from random head region and the half of these samples comprised control groups and the other half was irradiated with 1-5 Gy dose range. These samples were used to detect DNA damage by Comet assay technique depending on the dose of ionizing radiation. The tail length, tail moment values obtained from images were determined, so the dose-response curves generated. According to these curves, up to about 2 Gy dose values the tail moment and tail length values showed a linear increase, but decreased in the rhythm of increase in the higher dose. Applying comet assay technique in the hair roots collected from people who have been exposed to radiation, dose scan was done in them.The hair fiber (root part of the free), the other sample whose dosimetric characteristics is examined in case exposure to ionizing radiation irradiated with Co-60 radiation source. Clean hair samples were collected by volunteers, were grouped according to the color and whether the natural or dyed. Half of the samples as the control group, the other half are transferred to the packets, irradiated at low-dose (5-50 Gy) and high-dose (75-750 Gy) values. In ESR technique, these samples were used in determining the amount of dose-induced free radical. In all samples, the linear dose-response curves at low doses, was going to saturate after ~ 300 Gy. It was determined that unirradiated and irradiated samples could be distinguished even in the studied minimum dose (5 Gy) value. In black hair samples taken from different individuals, the differences in the structure of the spectrum and signal intensities were not observed. The ESR signal intensities of samples stored at room temperature for 22 days fell to their half values in 44 hour in DS, 41 hours in yellow and brown colors, 35 hours in BS and in 17 hour in red hair. Theoritical functions describing well the signal intensity decay data were searched and by this way the contribution of two and three radical species to natural and dyed hair samples? experimental spectra, respectively and their room temperature decay constants were determined. The decay activation energies of the radical species contributing to ESR spectra were calculated by taking into consideration the signal intensities decay data of the studied compounds annealed at high temperatures for different period of time. It was found that the calculated values of decay constants at room temperature and activation energies were correlated well with those obtained in the literature. With all these investigations, the conditions of hair samples in which they can be used as a biological dosimeter material were found. The dose estimation by ESR technique with samples of hairs should be done within 1-2 days after irradiation.