According to UNSCEAR classification Ramsar is classified in High-level Background Radiation Areas (HLBRA). The high level radiation in Ramsar is due to the existence of 226Ra, 222Rn and its progeny. The amount of radiation dose is very high in some houses. In the present studies the alkaline comet assay was used to evaluate the response of habitation of Ramsar’ peripheral blood mononuclear cells (PMNCs) to in vitro -irradiation at 0, 0.3, 1, 2 and 4 Gy with 60Co source. The PMNCs of 30 healthy donors from (HLBRA) as well as 20 control donors from adjacent place with non (HLBRA) were collected. The cells were stained with Ethidium Bromide and observed with fluorescent microscope to determine the DNA damage. The DNA damages show more heterogeneity than the control. In addition a significant difference (P<0.05) in the level of initial DNA damage between the test and the control group was observed immediately after exposure. Since some houses were naturally exposed to higher irradiation than the other, the cases were classified into two groups. It was found the inhabitants of the houses with higher dose of radiation were more sensitive and no adaptive response was observed. The effect of age was examined as well. The older inhabitants showed more damages in compared to the younger. The inhabitants who live in lower dose condition showed less damage and more repair in comparison with the control group. This can be related to adaptive responses. Many articles have pointed to the adaptive response and clastogenic factor. But our results show that these two dissimilar issues can occur. Two inhabitant groups of the same region who has similar nutrition but receive different doses show different responses. This response is correlated to their living conditions. The conclusion is that the occurrence of adaptive response and/ or clastogenic factor is related to the amount of the received dose and personal capabilities e.g. age and nutrition.
