Presentation on theme: "The Risk of Natural Radioactivity in the Environment A clinical & paraclinical experience on Ramsar Inhabitants Ali Shabestani Monfared, Seyed Mohamad."— Presentation transcript:
The Risk of Natural Radioactivity in the Environment A clinical & paraclinical experience on Ramsar Inhabitants Ali Shabestani Monfared, Seyed Mohamad Javad Mortazavi Babol University of Medical Sciences, Babol, Iran Rafsanjan University of Medical Sciences, Rafsanjan, Iran
Introduction There has always existed on earth a natural background radiation to which all living organisms are exposed. There exists the regions like Kerala in India, Yangjiang in China and Ramsar in Iran that the background radiation is much higher than the others in the world. [Sohrabi & Durrani, 1990- Wei, 1998- Nair, 1999] High natural background radiation areas (HBRA) have been extensively studied around the worlds. [UNSCEAR, 1988- Mishra et al, 1990- Mortazavi et al, 2002- Monfared et al, 2003]
Introduction (Cont.) The beautiful coastal city, Ramsar, located at the foot of the Elborz mountain and overlooking the Caspian sea, involves the highest background radiation among the whole residential areas in the world. [UNSCEAR, 2000]
Introduction (Cont.) The radioactivity of the area is mainly due to Ra-226 and its decay products, which have been brought up to earth surface by the water of hot springs. There are more than 50 hot springs with different concentrations of radium in the Ramsar which are usually used as spas by the residents and visitors.
Introduction (Cont.) The HBRA of Ramsar has been the subject of concern in the last forty years for a high level of radiation measured in some spots as high as 240 mSv y -1.[Sohrabi & Esmaili, 2002] It may be of interest to note that the maximum dose for radiation workers is 20 mSv y -1 and in order to prevent the possible radiation effects like cancer and genetic diseases, the dose to public should be less than 1 mSv y -1. [Publication No. 60, ICRP (1991 b) ].
Objective Several studies have been performed to assess the effects of the high background radiation on inhabitant health in Ramsar from different aspects such as cytogenetic studies (Fazeli & Assaei,1993), biological studies (Mortazavi et al, 2002) and immunological studies (Zakeri et al, 2004). The purpose of the present research was to study the health situation of the inhabitants of HBRA in Ramsar from the medical point of view. In this article, the most important point was to survey the present health status as an end point in radiobiological assessment of the inhabitants.
Materials & methods Among the whole inhabitants in Talesh Mahaleh in Ramsar as HBRA (127 families-504 people) and Chaparsar area with normal level of radiation (NBRA) (142 families – 506 people) [totally 1010 persons], (101 families- 402 persons) and (98 family-374 persons) [totally 776 persons], were selected respectively because of their permanent residency in the area and matching of some variables like sex, diet etc. Chaparsar (NBRA) Talesh mahale (HBRA)
Materials & methods (Cont.) Phase Ι After explaining the aim of the study for the individuals and satisfying them a questionnaire was prepared through observation to be sure that other intermediate factors affecting on the health are matched. It was included demographic features, a few socio-economical and health features like age, sex, job,education, income, period of residency, technical hygienic features of residential buildings, the way in which treating- hygienic services are received, diet, etc. Some items have been completed through available data in local health center of the areas.
Materials & methods (Cont.) Phase I Ι Another questionnaire in the form of modified Beck Test was also prepared to determine the range of depression among the puberty that lived in the two areas (298 people with the age of (34.3 ±11.21 years). Medical doctors examined the inhabitants and blood and urine samples were taken and analyzed.
Results The preliminary results of the phase 1 was presented at 6 th International conference on HLNRA in Osaka-Japan, 2004 & The 4 th International Conference of Low Radiation (WONUC), Hamilton, Ontario, Canada,2005 and is going to be published in IJLR 3 (3),2006.Also the complementary results of phase1 was presented at World Congress on Medical Physics and Biomedical Engineering, COEX Seoul, Korea,2006. Results showed that distributional frequency of the member of each family in two areas was equal (p-value = 0.083 ). Also in both areas the difference between the number of members of each family was not statistically significant (p-valve = 0.077). The average monthly income as one of the effective indicator on health standard, regardless of lack of clear answers in both areas was equal (p-value = 0.852) which is confirmed by applying non–parameteric tests. The findings showed that the number of disabled children and the cause of their disability (using the precise fisher test p – value = 0.197) and the frequency of depression and sex and age distribution of it, among the inhabitants of the two areas would not be statistically different.
Results (Cont.) In both areas the sex distribution and the standard of education were the same. The average of the residency period in Talesh mahaleh was 38 ± 24 and in Chaparsar was 40 ± 24 years and the difference was not statistically significant (p-value = 0.086). Some other criteria such as hygienic-technical situation of the two areas, storey and rooms, situation of the passages lead to these places, availability to hygienic drinking water, building skeleton, bath and lavatory, system of sewage disposal and dumping ground, keeping animals in the residential areas, etc, were the same. Although the fuel for heating system in both areas was not a like, there exist hygienic and separate chimneys. On account of being one medical center, there could not be observed any difference in receiving medical services.
Results (Cont.) * The differences were statistically significant (p<= 0.05) ** It was studied in 298 people in two areas. Area Age (years) Residency period (years) Congenital disabilities (No.) Cancer (No.) Cardiac diseases (No.) Age of death (years) Depression (No.) ** Talesh mahaleh n= 402 35.34 ± 20.76 38 ± 24221761 ± 243 Chaparsar n=374 33.83 ± 20.58 40 ± 24231466 ± 152
Results (Cont.) The mean age of the inhabitants, in HBRA and NBRA were 35.34 ± 20.76 and 33.83 ± 20.50 years respectively and the difference was not statistically significant. We found in the first phase of the study that the frequency of a few special diseases like cancer and cardiac disease in the HBRA could be less than the region with ordinary background radiation. However, the lower frequency of cancer and cardiac diseases in HBRA inhabitants was not confirmed by clinical examinations and paraclinical tests in the second phase of the study and there was no significant differences between the frequency of these diseases in the people who lived in those areas. Results showed that the rate of mortality has not been changed significantly since last year (p-valve = 0.678) and also the distribution of frequency of the causes of death was not different (p-value = 0.513). The distribution of frequency of abortion in the two areas were equal (p-value = 0.363).
Discussion & Conclusion Results showed that some important indicators on health such as economic and social features and a few hygienic indicators among the two residential areas were statistically equal. Therefore the possible observable changes in frequency of some diseases and health problems in the two areas could be independent from these factors. Results showed that the frequency of a few problems like congenital disabilities, abortion and depression among HBRA and NBRA inhabitants, as well as mortality rate, cardiac diseases and malignancies was similar. On the basis of ICRP recommendation for preventing of possible radiation effects like cancer and genetic diseases, the dose to population should be less than 1 mSv y -1 So this value for HBRA inhabitants is increased from 55 to 200 times and the lack of illness effect after receiving this dose cannot be adapted with this protection regulation (Mortazavi et al, 2002)
Discussion & Conclusion (Cont.) Some studies indicated that this level of radiation can be safe for human health (Ghiassi-nejad,2002) and to some extent this point is appropriate to the present study. The results showed that the frequency of some diseases and malignancies in HBRA is similar to the NBRA. Perhaps this finding represents the stimulation of immunity system through radiation (Ikushima, 1999). The outcomes which deal with no increasing the frequency of malignancies with HBR can be compared with some of other reports (Feinendegen & Bond, 1989 - Cohen, 2002). These findings also might be related to radiation adaptive response (Monfared et al, 2003).
Uncertainties & further researches The design of present study (cross sectional study) provides a situation analysis, rather than investigation of the effect of HBR on health. Although we used census method, lack of population in HBRA in Ramsar is a main source of uncertainty. A cohort study is going to established in cooperation with Japanese colleagues. In conclusion, our study may have not provided a strong support that living in HBRA in Ramsar is safe, but it definitely addresses the need for further extensive epidemiologic studies.