Content uploaded by SMJ Mortazavi
Author content
All content in this area was uploaded by SMJ Mortazavi
Content may be subject to copyright.
High Background Radiation Areas of Ramsar, Iran
S. M. J. Mortazavi, Ph.D
Professor of Medical Physics & Radiobiology
Medical Physics & Medical Engineering Department
and the Center for Research on Radiological Sciences
Shiraz University of Medical Sciences
E-mail: mmortazavi@sums.ac.ir
Humans, animals and plants have been exposed to natural
radiation since the creation of life. Interestingly, life
evolved in a radiation field that was much more intense
than today. The annual effective radiation dose from
natural and man-made sources for the world's population is
about 3 mSv, which includes exposure to alpha radiation
from radon and its progeny nuclides. Nearly 80% of this
dose (2.4 mSv) comes from natural background radiation,
although levels of natural radiation can vary greatly.
Ramsar, a northern coastal city in Iran, has areas with
some of the highest levels of natural radiation measured to
date. The effective dose equivalents in very high
background radiation areas (VHBRAs) of Ramsar in
particular in Talesh Mahalleh, are a few times higher than
the ICRP-recommended radiation dose limits for radiation
workers.
Figure 1. High Background Radiation Areas
Around the World. According to UNSCEAR
Page
1
of
7
Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
5/
9/
2013
http://www.sums.ac.ir/~mmortazavi/ramsar.html
2000 report, Ramsar, in northern Iran has
some inhabited areas with the highest known
natural radiation levels in the world. Figure
adapted from Health Research Foundation,
Kyoto, Japan with permission
Inhabitants who live in some houses in this area receive
annual doses as high as 132 mSv from external terrestrial
sources. The radioactivity of the high background radiation
areas (HBRAs) of Ramsar is due to Ra-226 and its decay
products, which have been brought to the surface by the
waters of hot springs. There are more than 9 hot springs
with different concentrations of radium in Ramsar that are
used as spas by both tourists and residents.
Figure 2. Hot water containing different
concentrations of Radium flows through
streams.
According to the results of the surveys performed to date
the radioactivity seems primarily to be due to the radium
dissolved in mineral water and secondarily to travertine
deposits having elevated levels of thorium combined with
lesser concentrations of uranium (Sohrabi 1990). Due to
extraordinary levels of natural radiation in these areas, in
some cases 55-200 times higher than normal background
Page
2
of
7
Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
5/
9/
2013
http://www.sums.ac.ir/~mmortazavi/ramsar.html
areas, some experts have suggested that dwellings having
such high levels of natural radiation need urgent remedial
actions (Sohrabi 1997). In spite of this, many inhabitants
still live in their unaltered paternal dwellings.
Figure 3. A calibrated survey meter shows the
contact dose rate.
The preliminary results of cytogenetical, immunological
and hematological studies on the residents of high
background radiation areas of Ramsar have been
previously reported (Mortazavi et al. 2001, Ghiassi-Nejad
et al. 2002 and Mortazavi et al. in press), suggesting that
exposure to high levels of natural background radiation can
induce radioadaptive response in human cells.
Lymphocytes of Ramsar residents when subjected to 1.5
Gy of gamma rays showed fewer induced chromosome
aberrations compared to residents in a nearby control area
whose lymphocytes were subjected to the same radiation
dose. Despite the fact that in in vitro experiments
lymphocytes of some individuals show a synergistic effect
after pretreatment with a low dose(Mortazavi et al. 2000),
none of the residents of high background radiation areas
showed such a response.
Page
3
of
7
Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
5/
9/
2013
http://www.sums.ac.ir/~mmortazavi/ramsar.html
Figure 4. A scientist is measuring the dose rate
around these HOT oranges!
Based on results obtained in studies on high background
radiation areas of Ramsar, high levels of natural radiation
may have some bio-positive effects such as enhancing
radiation-resistance. More research is needed to assess if
these bio-positive effects have any implication in radiation
protection (Mortazavi et al. 2001). The risk from exposure
to low-dose radiation has been highly politicized for a
variety of reasons. This has led to a frequently exaggerated
perception of the potential health effects, and to lasting
public controversies.
Figure 5. A group of scientists from Korea,
Japan, India and USA are visiting HBRAs of
Ramsar.
Page
4
of
7
Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
5/
9/
2013
http://www.sums.ac.ir/~mmortazavi/ramsar.html
Current radiation protection recommendations are based
on the predictions of an assumption on linear, no-threshold
dose-effect relationship (LNT).Beneficial effects and lack
of detriment after irradiation with low levels of ionizing
radiation, including a prolonged exposure to high levels of
natural radiation of the inhabitants of HBRAs, are
inconsistent with LNT (Mortazavi et al. 1999).
Our preliminary results suggest that prolonged exposure
to very high levels of natural radiation could lead to the
induction of radiation resistance among exposed
individuals, which has interesting implications for many
aspects of radiation protection policy.
Figure 6. Experts are measuring dose rates in
different points of an inhabited area.
The phenomenon of radioresistance in living organisms
has long been a matter of interest for scientists.
Experiments on Drosophila nebulosa collected in the
woods of a high background radiation area in Brazil
indicated the addition of some genes caused the
radioresistance found in these flies compared to flies
collected from adjacent control woods. In humans it is also
possible that genetic alterations have occurred over the
span of many generations to induce the radioresistance
noted in our study. More research is needed to clarify the
mechanisms that make individuals radioresistant.
Page
5
of
7
Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
5/
9/
2013
http://www.sums.ac.ir/~mmortazavi/ramsar.html
Figure 7.a. Two survey meters show the dose rates
of 142 and 143 micro Gy/h on the wall of the
bedroom of one dwelling.
Figure 7.b. The survey meter shows the dose
rate on the bed.
There are many other areas with high levels of
background radiation around the world, and
epidemiological studies have indicated that natural
radiation in these areas is not harmful for the inhabitants.
Results obtained in our study are consistent with the
hypothesis that a threshold possibly separates the health
effects of natural radiation from the harm of large doses.
This threshold seems to be much higher than the greatest
level of natural radiation.
Page
6
of
7
Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
5/
9/
2013
http://www.sums.ac.ir/~mmortazavi/ramsar.html
References
1. Ghiassi-nejad, M; Mortazavi, SMJ; Cameron, JR;
Niroomand-rad, A; Karam, PA; Very High Background
Radiation Areas of Ramsar, Iran: Preliminary Biological
Studies. Health Physics, 82(1): 87-93, 2002.
2. Mortazavi SMJ, Mozdarani H. Is it time to shed some
light on the black box of health policies regarding the
inhabitants of the high background radiation areas of
Ramsar? Iranian Journal of Radiation Research. 2012;10
(3-4):111-6.
3. Mortazavi SMJ, Niroomand-Rad A, Mozdarani H,
Roshan-Shomal P, Razavi-Toosi SMT, Zarghani H. Short-
term exposure to high levels of natural external gamma
radiation does not induce survival adaptive response.
Iranian Journal of Radiation Research. 2012;10(3-4):165-
70.
4. Mortazavi SMJ, Mozdarani H. Non-linear phenomena in
biological findings of the residents of high background
radiation areas of Ramsar. International Journal of
Radiation Research. 2013;11(1):3-9.
Important Note:
The contents of this publication may be reproduced or
reprinted without permission of the author as long as the
source is clearly acknowledged.
Page
7
of
7
Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
5/
9/
2013
http://www.sums.ac.ir/~mmortazavi/ramsar.html