Presentation on theme: "Dose-Response Relationship: Health Effects In Residents at the High Background Radiation Areas of Ramsar, Iran SMJ Mortazavi, Ph.D Associate Professor."— Presentation transcript:
Dose-Response Relationship: Health Effects In Residents at the High Background Radiation Areas of Ramsar, Iran SMJ Mortazavi, Ph.D Associate Professor of Medical Physics Rafsanjan University of Medical Sciences, Imam Ali Blvd., Rafsanjan, Iran.
Mortazavi SMJ Radiation and Life Life evolved in a radiation field that was much more intense than today. –Higher Concentration of Radioactive Elements –Natural Reactors Natural background radiation levels on Earth vary by at least two orders of magnitude.
Mortazavi SMJ Radioadaptation History It has been long known that protozoa and bacteria exposed to artificially lowered levels of natural radiation demonstrate deficiency symptoms expressed as dramatically decreased proliferation.
Mortazavi SMJ Natural Radioactivity and Radioresistance Radioresistance in living creatures of high background radiation area has long been a matter of interest for scientists. More than thirty years ago, experiments on the Drosophila nebulosa showed that the flies collected in a high background radiation area in Brazil were more radioresistant than those of an adjacent area (Kratz 1974).
Mortazavi SMJ According to UNSCEAR 2000 report, Ramsar, a city in northern Iran has some inhabited areas with the highest known natural radiation levels in the world.
Mortazavi SMJ Why so Hot?
Mortazavi SMJ Radium Carbonate When the groundwater reaches the surface at hot spring locations, travertine, a calcium carbonate mineral (CaCO 3 ), precipitates out of solution with dissolved radium substituting for calcium in the mineral. Radium Carbonate （ RaCo 3 ） Molecular Weight Color: White
Mortazavi SMJ Radioactive Bedroom Two survey meters show the dose rates of 142 and 143 μGy/h on the wall of the bedroom of one dwelling. The owner has used the sedimentary stones formed at hot springs for construction of his house.
Mortazavi SMJ Where Do We Need Regulations? The ICRP-recommended annual effective dose limit for radiation workers is 20 mSv. The annual effective dose in HLNRAs of Ramsar is a few times higher than this limit.
Mortazavi SMJ Where Do We Need Regulations? (cont.) City of Pripyat, (near Chernobyl) Ukraine Permanently Evacuated Nuclear accident fallout 5.0 mSv/year
Mortazavi SMJ Prof. Sohrabi yesterday stated that the residents of Ramsar have been always considered as laboratory mice. No Help for Relocation No Economic Assistance No Remedial Action No Long-term or Short-Term Plan! Just continuous sampling (blood, teeth! … )
Mortazavi SMJ Expense of Remedial Actions Because of the expense of remedial actions and the long history of high background radiation levels, it is nearly impossible to ask the inhabitants to carry out remedial actions.
Mortazavi SMJ Should the Residents be aware of the extra high radiation levels in their environment? Should the government financially help them to do remedial actions (basements, floors … ) or even evacuate the HBRAs? Why these are not simple questions?
Mortazavi SMJ Lesson Learned From Chernobyl Accident: Health effects caused by radiation Health effects caused by fear of radiation Psychological considerations Economic considerations (land Cost) Social considerations (relocation)
Mortazavi SMJ Radon in Ramsar Radon levels up to 3700 Bq/m3 (over 100 pCi/L). The people and their ancestors exposed to abnormally high radiation levels over many generations. If a radiation dose of a few hundred mSv per year is detrimental to health causing genetic abnormalities or an increased risk of cancer, it should be evident in these people.
Mortazavi SMJ Radon Prone Houses It is often difficult to sell a radon prone house in the US or in other developed countries It is nearly impossible to ask the inhabitants of high level natural radiation areas HLNRAs of Ramsar to carry out remedial actions.
Mortazavi SMJ Study Design Ramsar is divided into eight health districts and a health center provides primary health services in each health district. Indoor radon concentration levels were previously measured in each dwelling by the Iranian Nuclear Regulatory Authority experts.
Mortazavi SMJ Cancer Mortality The overall cancer mortality, lung cancer mortality and neonatal death rate of different districts in the years from 2000 to 2001 were collected. The radon prone houses were located in a district named Ramak.
Mortazavi SMJ Surprising Results Our study showed that the highest lung cancer mortality rate was in Galesh Mahaleeh, where the radon levels are normal. On the other hand, the lowest lung cancer mortality rate was in Ramak, where the highest concentrations of radon in the dwellings were found
Mortazavi SMJ Crude Lung Cancer Rate
Mortazavi SMJ Adjusted Lung Cancer Rate
Mortazavi SMJ Adaptive Response Table 3: Frequency of chromosomal aberrations in non-irradiated and irradiated cells of the residents of high background radiation areas and the residents of the control area.
Dose and k-Value The 2nd-order polynomial model indicates an optimal induction of error-free DNA repair in a cumulative dose region of min k-value.
HBRAs and the Radiation Protection Policy Considering LNT and ALARA, residents ’ health could be severely affected and public health in HBRAs like Ramsar would be best served by relocating the inhabitants. In spite of this, the residents ’ health seems unaffected and relocation is upsetting to the residents (Mortazavi and Karam 2002)
Mortazavi SMJ Other HBRAs ’ Biological Findings Based on the findings obtained by studies on the health effect of high levels of natural radiation in other HBRAs: No consistent detrimental effect has been detected so far.
Mortazavi SMJ Other HBRAs (cont.) The level of natural radiation in Kerala is about 10 times higher than that of normal background areas. The average life span of Kerala residents is 72 years, while for all India, it is only 54 years (Goraczko 2000).
Mortazavi SMJ Should we replace the LNT with better Models? Dr. Comby ’ s ALAIN?
Mortazavi SMJ Mortazavi et al., Advances in Space Research, Vol 31, No. 6, , 2003