Radioadaptive responses induced in lymphocytes of the inhabitants in Ramsar, Iran

Abstract

Ramsar, a city in northern Iran, has among the highest levels of natural radiation known to exist in an inhabited area. Twenty-two residents of high-level natural radiation areas and 33 residents from an adjacent normal-level natural radiation area participated in this study. In the first phase of the experiment, 15 healthy residents from high-level natural radiation areas and 30 healthy inhabitants of a nearby normal-level natural radiation area were studied. In the second phase, seven healthy residents with cumulative lifetime doses of up to 10 Sv were studied for assessing the induction of adaptive response in each study participant and obtaining complementary data. Cultured cells were given a challenge dose of either 2 Gy (first phase of the study) or 1.5 Gy (second phase of the study) of Co-60 gamma radiation. Overall data showed a significant radioadaptive response in the residents of high-level natural radiation areas. Results obtained in the second phase of the study showed that five out of seven inhabitants exhibited a reduction in induced chromosomal aberrations following exposure to a 1.5 Gy challenge dose of gamma radiation. As the cumulative dose increased from a few hundred mGy to 1 Gy, the magnitude of the induced adaptive response increased linearly.