Micronucleus Assay‑based Evaluation of Radiosensitivity of Lymphocytes among Inhabitants Living in High Background Radiation Area of Mamuju, West Sulawesi, Indonesia

Naturally occurring radiation can be found all around us and account for most of the radiation received by human beings each year. Indonesia
has a region with high‑dose natural radiation located in the suburb of West Sulawesi province with a dose rate up to 2800 nSv/h; however, its
impact was not fully understood. The aim of this study was to evaluate the radiosensitivity of 12 peripheral blood lymphocytes of inhabitant from
high background radiation area (HBRA) and 10 from normal background radiation area (NBRA) based on cytokinesis‑block micronucleus (CBMN)
assay after challenged with 1.5 Gy of gamma ray. The analysis of CBMN was done according to standard procedure as per IAEA guidelines, and
frequency of binucleate (mitotic) cells with micronuclei (MN) was scored in around 2000 binucleate lymphocytes cells per culture in microscopic
analysis. Mean MN frequency for HBRA was lower than that of NBRA (0.121 vs. 0.189) after irradiation, indicating an adaptive response in HBRA
group that resulted in less radiosensitivity; however, there was no statistically significant different (P > 0.05) between these two groups. The
MN number was higher in women compared to men for both HBRA (0.15 vs. 0.09) and NBRA (0.216 vs. 0.147) groups. Besides, there was no
statistically significant difference (P > 0.05) in Nuclear Division Index (NDI), as measured in 500 metaphase cells with published formula, between
HBRA and NBRA samples (1.24 vs. 1.21). The lower MN frequency prompts us to conclude that there is an adaptive response in the lymphocytes
of inhabitants as an indicator of lower radiosensitivity to the high natural radiation exposure. Further studies using large number of samples
are required to obtain more comprehensive conclusion along with the assessment of other types of radiosensitivity‑related biomarkers