Assessment of Individual Radiosensitivity in Inhabitants of Takandeang Village - A High Background Radiation Area in Indonesia

People living in high background radiation areas (HBRAs) possibly develop the
radioadaptive response (RAR) phenomenon. The Mamuju area in West Sulawesi
Indonesia is known as an HBRA in Indonesia due to its high natural uranium
contents. It is possible that RAR has developed in Mamuju inhabitants. To prove
this hypothesis, here in this study, evaluation of the individual radiosensitivity in the
inhabitants of Takandeang Village, Mamuju, was conducted using G2 micronucleus
(MN) assay. Association between blood groups and TP53 Arg72Pro polymorphism
with individual radiosensitivity was also evaluated in this study. Using G2 MN
assay, we assessed the individual radiosensitivity of Takandeang Village inhabitants
and control samples. For each sample, three parameters were calculated.
The spontaneous (baseline) MN number, MN number after 0.5 Gy in vitro
irradiation, and radiation-induced MN were calculated to predict the individual
radiosensitivity. The radiation-induced MN was defined by subtracting the
spontaneous MN number from the MN number after irradiation. The mean and SD
of the number of micronuclei induced by radiation found in control group (CG)
was set as the cutoff value to determine the individual radiosensitivity in all
samples. The occurrence of a radiation-induced MN value higher than the
mean CG + 1SD CG was scored as 1, indicating a milder radiosensitive phenotype,
whereas a result higher than the mean CG + 2SD CG was scored as 2, and indicated
a more severe radiosensitive phenotype. When the individual value was lower than
the mean CG + 1SD CG, a score of 0 was attributed to the tested subject.
The results showed that four individuals in Takandeang Village inhabitants had a
milder radiosensitive phenotype, while the others were categorized as normal
radiosensitive. A similar finding was also found in control samples. Our study failed
to find any correlation between radiosensitivity and either blood group or the TP53
Arg72Pro polymorphism. Overall, our study revealed the possibility of RAR
phenomena in Takandeang Village inhabitants. Further investigation using a
different point of radiation dose value and larger sample number should be
performed to validate this study results.