Assessment of Cancer Risk to the Human Tissues Related to Public Exposure to Cesium-137

Hashim Ameen Al-Tameemi, Nabeel

	Assessment of Cancer Risk to the Human Tissues Related to Public Exposure to Cesium-137
Al-Mustansiriyah Journal of Science
Article 1, Volume 21, Issue 6, 2010, Pages 230-243
Author
Nabeel Hashim Ameen Al-Tameemi
Abstract
Multi-step risk assessment process was used in characterization of probable health hazards caused by exposure of local inhabitants live in the urban areas that surrounds Al-Twaitha nuclear research site (Hay Al-Riyad and Jesr-Diyala sectors) to 137Cs through environmental pathways (air and food) using a hypothetical linear no threshold (LNT) statistical model. The gamma-ray activity concentrations of 137Cs in soil samples were measured using gamma-ray spectroscopy system. A typical model developed for radiological assessment was used to evaluate principal pathways for 137Cs transfer from soil to human through environmental pathways (soil to vegetation transfer, ingestion of animal products, and inhalation of resuspended 137Cs particles). The annual effective dose equivalents were determined from the annual intake of 137Cs using dosimetric parameters based on International Atomic Energy Agency (IAEA) publications. The results of this study show that cesium-137 contributes about 0.622 Sv/y to the average annual total effective dose equivalent for the exposed population. The animal products pathway is found to be the most significant route and the most exposed organs are found to be the colon. The individual doses resulting from the consumption of animal products are one to two orders of magnitude higher than doses delivered from the consumption of vegetables. For the population as a whole, ingestion is a minor route of entry of 137Cs into the body; food is generally the main source of intake. The results of this study indicate that exposure of respective population to 137Cs cause considerable carcinogenic risks to a large number of people. The lifetime (70 years) fatal cancer risk to a population receives 50.108 Bq of 137Cs per year is found to be about 2. 172 expected fatal cancer case per million exposed individuals, or there is one additional death as a result of radiation-induced cancer incidence in a group of 460405 people if they would all receive 137Cs at a rate of 50.108 Bq per year instantaneously. The probability of having a genetic damage by radiation for all generations is estimated to be about 1 per 2304147 or 4 per 10 million in parents who were irradiated before conception occurred. Direct comparison of the estimated dose and radiation–derived risk with the guidelines indicates that people are exposed to 137Cs radioactivity within acceptable dose and risk limits. The annual limit on 137Cs intake established by the International Atomic Energy Agency is translated in this study into a corresponding derived maximum permissible concentration in food crops and agricultural soil through the use of environmental pathway modeling. I

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