<p>Dicentric chromosome analysis (DCA) has limitations in its use for the evaluation of the radiation dose upon the development of medical radiation equipment due to its time/labour-consuming procedure and the requirement of highly trained experts. Therefore, we aimed to construct a dose–response curve using a semi-automatic cytokinesis-block micronucleus (CBMN) analysis method that can be easily analysed and utilised by anyone. CHO-K1 cells were exposed to gamma rays at various doses (0–4 Gy). For the CBMN assay, the bi-nucleated cells were selected and captured, and micronuclei (MN) scoring was automatically performed using the Metafer4 system. The MN scores were manually confirmed and corrected by analysts. Using the frequency distributions of MN according to the radiation dose, the dose–response calibration curve was generated using Dose Estimate v5.2 software. The equation of dose–response calibration curve is Y = 0.0299 (±0.0057) + 0.1502 (±0.0151) × D + 0.0111 (±0.0048) × D2. The goodness-of-fit parameters were also calculated (chi-squared [χ 2] = 39.45, degrees of freedom = 5, p = 0.0000). The semi-automated CBMN assay consist of two steps: the automated MN capture/scoring step and the manual confirmation/correction step. Using an established dose–response calibration curve and the procedure of the semi-automated CBMN assay, the dose-estimation of gamma-irradiated (0.5 or 2 Gy) CHO-K1 cells were performed by two analysts individually, and it was inter-compared to verify the accuracy, the results showed that the estimated doses were a good fit the applied doses of radiation. The CBMN assay using CHO-K1 cells can be easily used as a biodosimetry tool for dose assessment of medical radiation equipment due to the advantage of being simple, easy, and quick to measure the dose.</p>

Digital object identifier (DOI): 10.14293/genint.15.1.003

<p>Human exposure to radiofrequency electromagnetic fields (RF-EMF) is restricted to prevent thermal effects in the tissue. However, at very low intensity exposure "non-thermal" biological effects, like oxidative stress, DNA or chromosomal aberrations, etc. collectively termed genomic-instability can occur after few hours. Little is known about chronic (years long) exposure with non-thermal RF-EMF. We identified two neighboring housing estates in a rural region with residents exposed to either relatively low (control-group) or relatively high (exposed-group) RF-EMF emitted from nearby mobile phone base stations (MPBS). 24 healthy adults that lived in their homes at least for 5 years volunteered. The homes were surveyed for common types of EMF, blood samples were tested for oxidative status, transient DNA alterations, permanent chromosomal damage, and specific cancer related genetic markers, like MLL gene rearrangements. We documented possible confounders, like age, sex, nutrition, life-exposure to ionizing radiation (X-rays), occupational exposures, etc. The groups matched well, age, sex, lifestyle and occupational risk factors were similar. The years long exposure had no measurable effect on MLL gene rearrangements and c-Abl-gene transcription modification. Associated with higher exposure, we found higher levels of lipid oxidation and oxidative DNA-lesions, though not statistically significant. DNA double strand breaks, micronuclei, ring chromosomes, and acentric chromosomes were not significantly different between the groups. Chromosomal aberrations like dicentric chromosomes (p=0.007), chromatid gaps (p=0.019), chromosomal fragments (p&lt;0.001) and the total of chromosomal aberrations (p&lt;0.001) were significantly higher in the exposed group. No potential confounder interfered with these findings. Increased rates of chromosomal aberrations as linked to excess exposure with ionizing radiation may also occur with non-ionizing radiation exposure. Biological endpoints can be informative for designing exposure limitation strategies. Further research is warranted to investigate the dose-effect-relationship between both, exposure intensity and exposure time, to account for endpoint accumulations after years of exposure. As established for ionizing radiation, chromosomal aberrations could contribute to the definition of protection thresholds, as their rate reflects exposure intensity and exposure time.</p>

Digital object identifier (DOI): 10.1016/j.ecoenv.2024.116486