Review on studies in high background radiation areas (HBRAs) of various parts of the world

The present paper reviews the studies of populations living in high background radiation areas (HBRA). Past studies have shown that high background radiation has been repeatedly shown to increase the frequency of chromosome aberrations in the circulating lymphocytes of exposed persons, but its carcinogenic effect is still unproven. A further area of research is whether long term exposure to background radiation cause DNA damage, which was evaluated by determination of the frequency of micronucleus formation and it was suggested that a challenging dose rendered the cells of those who live in HBRAs less susceptible to damage compared to the control group in normal background radiation area (NBRA). It has also been reported that higher level of apoptosis was observed after the challenging dose in the HBRA group. It was also remarkable that after introducing a challenging dose, the major part of the damage induced in the HBRA groups, were repaired indicating the improved repair ability within them, which was detected using comet assay. In addition, studies have found significant differences in certain immunological parameters suggestive of an active immune surveillance there and hematological parameters and various other parameter studies was not significant between those in high and normal background radiation area. All these studies could be related to the induction of an adaptive response in the individuals of HBRA.