Very High Background Radiation Areas (VHBRAs) of Ramsar: Do We Need Any Regulations to Protect the Inhabitants?
M. Ghiassi-Nejad, S. M. J. Mortazavi, M. Beitollahi, R. Assaie, A. Heidary, R. Varzegar, F. Zakeri, M. Jafari
Ramsar, a coastal northern city of Iran located at the foot of the Alburz Mountains and overlooking the Caspian Sea, has some areas with elevated levels of natural radiation. The effective dose equivalents in VHBRAs of Ramsar in particular in Talesh Mahelleh, are few times higher than the dose limits for radiation workers. The basic aim of this paper is to answer the question on whether Iranian policy makers should approve a series of rules to decrease the irradiation of the inhabitants of VHBRAs of Ramsar. Despite the fact that previous cytogenic studies have shown some significant differences between the results of the exposed group and the control, our recent studies indicated that there is no significant difference. In addition, the population living in areas with high levels of natural radiation (HLNR) around the world does not reveal increased cancer or leukemia incidence. Obviously, this is inconsistent with the predictions of the linear, no-threshold hypothesis (LNT), on which the current radiation protection recommendations are based. Since the inhabitants of Ramsar live there since many generations, we started a study to assess whether they developed a radioadaptive response to the high dose rate of natural radiation. The frequency of chromosome aberrations (CA), activity of the immunity system, hematological alterations and induction of repair proteins were among the main end-points of this study. Interestingly, our preliminary results indicated that the frequency of CA in lymphocytes of the inhabitants of VHBRAs after exposure to a challenge dose of 1.5 Gy Gamma rays, was significantly lower than that of the inhabitants of a normal background radiation area (NBRA). In spite of the lack of any data on harmful effects of natural radiation, as the annual dose of the inhabitants of Ramsar is much higher than other HBRAs in the world, we recommend that whenever it is reasonable (e.g., the construction of new schools or any other public places in the VHBRAs) the unnecessary irradiation of the inhabitants should be decreased. In this regard, it can be concluded that the Iranian Nuclear Regulatory Authority (INRA) should control the construction of any new buildings, especially public places in the VHBRAs of Ramsar in the future.
This abstract was presented at the 34th Annual Midyear Meeting, "Radiation Safety and ALARA Considerations for the 21st Century", Regulatory Considerations Session, 2/4/2001 - 2/7/2001, held in Anaheim, CA.