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High Background Radiation Areas of Ramsar, Iran

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http://www.sums.ac.ir/~mmortazavi/ramsar.html 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. 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. 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 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. 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. 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. 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. 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. 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. 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.
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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
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Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
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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
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7
Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
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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.
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Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
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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.
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Natural Radiation: High Background Radiation Areas (HBRAs) of Ramsar, Iran
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... Cancer risk is lower in geographic regions with an abnormally high radiation background, which is associated with stimulation of anticancer immune defense by radiation and, hence, with the harmlessness of exposures to low doses [137] [138] [139] [140] [141]. According to this logic, hormesis is supposed to be the missing link to a better cancer treatment [142]. ...
... Background radiation causes nearly 80% of annual total radiation dose that a person is exposed to, which is 2.4 mSv per person. About 54% of the total external dose originates from K-40, Ra-226 and Ra-228 received by the public (6,7). One of the main determinants of the background radiation is soil radioactiv-ity concentration (8). ...
Article
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Background: The health implication of exposure to gamma radiation in the outdoor and indoor environments has become a major concern worldwide. Methods: This study was conducted in the city of Birjand where three stations and buildings were randomly selected to measure the background radiation in outdoor and indoor places; for this purpose, GM detector (X5C plus) was used. All dose rates on the display of the survey meter were recorded, and the mean of all data in each station and buildings was computed and taken as the measured dose rate of that particular station. Results: The average dose rate of background radiation was 71.8 nSv/h for outdoor and 82.0 nSv/h for indoor environments, and the maximum and minimum dose rates were 79.6 nSv/h and 61.7 nSv/h for outdoor measurements and 112.9 nSv/h and 70.8 nSv/h for indoor measurements, respectively. Conclusions: The results revealed that the annual effective dose is 0.49 mSv, which is similar to that of the global level (0.48 mSv). The estimated excess lifetime cancer risk was 1.715 × 10-3, which was high compared to the world average value of 0.25 × 10-3.
... Life began in a radiation field that is more intense than that of today (Mortazavi, 2012); the radiation level today is ten-fold lower than that during the Precambrian era (Karam and Leslie, 2005;Møller and Mousseau, 2013). One of the radionuclides in man's environment that contributes a large proportion of the radiation dose to the population is radon (Bavarnegin et al., 2013). ...
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Background The health implication of exposure to gamma radiation in the outdoor and indoor environments has become a major concern worldwide. Methods This study was conducted in the city of Birjand where three stations and buildings were randomly selected to measure the background radiation in outdoor and indoor places; for this purpose, GM detector (X5C plus) was used. All dose rates on the display of the survey meter were recorded, and the mean of all data in each station and buildings was computed and taken as the measured dose rate of that particular station. Results The average dose rate of background radiation was 71.8 nSv/h for outdoor and 82.0 nSv/h for indoor environments, and the maximum and minimum dose rates were 79.6 nSv/h and 61.7 nSv/h for outdoor measurements and 112.9 nSv/h and 70.8 nSv/h for indoor measurements, respectively. Conclusions The results revealed that the annual effective dose is 0.49 mSv, which is similar to that of the global level (0.48 mSv). The estimated excess lifetime cancer risk was 1.715 × 10-3, which was high compared to the world average value of 0.25 × 10-3.
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An important radioactive, colorless and odorless gas emitted from natural radium existing in the ground, radon is an element of the U238 chain. Based on conducted studies, Ramsar has been recognized as one of the most polluted areas in the world as far as the exhalation of radon is concerned. The most important resources of radon in Ramsar are soil resources, water resources, groundwater, surface water and hot springs. In this study, 50 stations in high radioactivity areas of Ramsar were selected and the position of each station in terms of latitude and longitude was recorded with a GPS device; then, radon exhalation and gamma dose rates were measured using an AlphaGuard device and a portable gamma spectroscopy system, respectively. Furthermore, some environmental parameters such as temperature, pressure, relative humidity, the distance of each station from the mineral hot springs, the time interval between the rainfall and the day of measurement, soil moisture status and also weather conditions at the time of measurement were recorded, and the effect of measured environmental parameters on the radon exhalation rate was subsequently evaluated using Spss software and finally modeled by linear regression method. The gamma dose rate was around 58-7100 n.sv/hr and the radon exhalation rate was about 9-15370 mBq/m2.s. In this study, only the variables of gamma dose rate and soil moisture were effective on exhalation rate. The correlation between gamma dose and radon exhalation rate was significant and higher than the other variables. Results indicate that the estimated average annual effective Radon exhalation rate for the study area is much higher than the worldwide average figure of 16 mBq/m2.s reported by UNSCEAR. It can therefore be concluded that an assessment of the radiological hazard of living these area is crucial.
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Ionizing radiation during pregnancy can negatively impact a fetus. In light of the Fukushima nuclear plant disaster in Japan, we discuss existing knowledge on the health effects of radiation and preventive measures for pregnant women. Overall, the risk of exposure to radiation is limited but severe defects can result from fetal radiation exposure >100 mGy equivalent to 10 rad (>1000 chest x-rays). While such high-level exposure rarely occurs during single medical diagnostic procedures, caution should be exercised for pregnant women. As a protective public health measure in light of a disaster, evacuation, shielding, and elimination of ingested radioactive isotopes should all be considered. Detailed radiation reports with health effects and precautionary measures should be available for a population exposed to more than background radiation.
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Although there are substantial experimental, epidemiological and clinical evidences that high doses of ionizing radiation cause cancer and other detrimental biological effects, the health effects of human exposure to chronic low dose radiation exposures are still poorly known. People in some areas around the world live in dwellings with radiation and radon levels as much as more than 200 times the global average. Inhabited areas with high levels of natural radiation are found in different areas around the world including Yangjiang, China; Kerala, India; Guarapari, Brazil and Ramsar, Iran. Ramsar in northern Iran is among the world’s well-known areas with highest levels of natural radiation. Annual exposure levels in areas with elevated levels of natural radiation in Ramsar are up to 260 mGy y-1 and average exposure rates are about 10 mGy y-1 for a population of about 2000 residents. Due to the local geology, which includes high levels of radium in rocks, soils, and groundwater, Ramsar residents are also exposed to high levels of alpha activity in the form of ingested radium and radium decay progeny as well as very high radon levels in their dwellings. Based on the findings obtained by studies on the health effect of high levels of natural radiation in Ramsar, as well as other high background radiation areas, no consistent detrimental effect has been detected so far. Further research is needed to clarify if the regulatory authorities should set limiting regulations to protect the inhabitants against such extraordinary elevated levels of natural radiation. Iran. J. Radiat. Res., 2012; in press
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Background: In some areas of Ramsar, a city in northern Iran, residents receive a much higher annual radiation exposure than is permitted for radiation workers. Induction of adaptive response in residents of Ramsar has been reported previously. In this study induction of such a response in short term exposure to high background levels of gamma radiation is investigated. Materials and Methods: Fifty male NMRI mice were randomly divided into four groups of 10-17 animals and 53 Wistar rats were randomly divided into five groups of 10-12 animals were studied. Animals in the 1st group were kept for 7 days in an outdoor area with normal background radiation while the 2nd, 3rd, 4th and 5th (in case of rats) groups were kept in 3 different outdoor areas with naturally elevated levels of gamma radiation. Animals were then exposed to a lethal dose of 8 Gy gamma radiation. Results: For mice, 30 days after exposure to lethal dose, the survival fraction for the control group was 40% while the 2nd, 3rd, and 4th groups had survival rates of 20%, 33.30%, and 35.20%, respectively. For rats, 30 days after exposure to the lethal dose, the survival fraction for the control group was 40% while the 2nd, 3rd, 4th and 5th groups had survival rates of 20%, 41.6%, 60.0% and 35.7%, respectively. Conclusion: Results indicate that shortterm exposure to extremely high levels of natural gamma radiation (up to 196 times higher than the normal background) do not lead to induction of survival adaptive response. Iran. J. Radiat. Res., 2012; in press.
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Full-text available
People in some areas of Ramsar, a city in northern Iran, receive an annual radiation absorbed dose from background radiation that is up to 260 mSv y(-1), substantially higher than the 20 mSv y(-1) that is permitted for radiation workers. Inhabitants of Ramsar have lived for many generations in these high background areas. Cytogenetic studies show no significant differences between people in the high background compared to people in normal background areas. An in vitro challenge dose of 1.5 Gy of gamma rays was administered to the lymphocytes, which showed significantly reduced frequency for chromosome aberrations of people living in high background compared to those in normal background areas in and near Ramsar. Specifically, inhabitants of high background radiation areas had about 56% the average number of induced chromosomal abnormalities of normal background radiation area inhabitants following this exposure. This suggests that adaptive response might be induced by chronic exposure to natural background radiation as opposed to acute exposure to higher (tens of mGy) levels of radiation in the laboratory. There were no differences in laboratory tests of the immune systems, and no noted differences in hematological alterations between these two groups of people.