Pakistan Research Repository

MEASUREMENT OF NATURAL RADIOACTIVITY IN SOIL, INDOOR RADON LEVEL AND EXCESS CANCER RISK IN BAHAWALPUR DIVISION

Abdul, Ahad (2004) MEASUREMENT OF NATURAL RADIOACTIVITY IN SOIL, INDOOR RADON LEVEL AND EXCESS CANCER RISK IN BAHAWALPUR DIVISION. PhD thesis, Islamia University, Bahawalpur.

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Abstract

Radioactivity is one of the major causes of cancer especially in non-smokers. The objective of this work was to measure radioactivity in soil, indoor radon concentration levels and to assess their effects on human health in thickly populated areas of Bahawalpur Division of Pakistan, which is larger in area than more than forty countries of the world. The activities of 226Ra, 232Th and 40K were measured in soil and vegetation using an HPGe based gamma spectrometry system. Since these activities do not reflect clearly the hazards associated with these materials the radium equivalent activity and the external and internal hazard indices were determined for these materials. The highest average value of radium equivalent activity is 173.6 Bq Kg-1 for soil and 34.88 Bq Kg-1 for vegetation. The lowest average value of radium equivalent activity is 148.4 Bq Kg-1 for soil and 23.15 Bq Kg-1 for vegetation. The ranges of external and internal hazard indices for soil arc 0.4-0.5 and 0.5-0.6 respectively whereas the range of these values for vegetation is 0.02-0.05. All these values are less than the recommended limiting value of radium equivalent activity as 370 Bq Kg-1 and hazard indices as <1.The transfer factors. which describe the transfer of activity from soil to vegetal on, were also determined. Nuclear weapon tests and nuclear accidents caused the spread of man made So., the activity of 137Cs was also measured the maximum average value of which was found equal to 2.6 Bq Kg-1 From the measured values of all the four radionuclides the feasibility of soil for construction material was determined and found safe for all the construction purposes. The annual external dose equivalent was determined for oil. The highest average value of 0.51 mSv Y-1 was estimated for the soil of Minchinabad. and the lowest value of 0.46 mSv y-1 for Fort Abbas, Derawer Fort, Rahimyar khan and Sadiqabad. The dose to whole body ranges from (, 22 mSv y-1 to 0.24 mSv y-1.. From dose equivalents the absorbed dose to various organs and whole body were calculated. which were used to estimate the cancer risks. These risks were then compared with the available record of a cancer hospital present in Bahawalpur City. Indoor radon concentration levels were measured in seven towns using bag dosimeters. The highest average value of radon concentration measured in bedrooms using CR-39 detector containing dosimeters of 47 Bq/m3 was found in Liaqatpur followed by 42 Bq/m3 in Bahawalpur. The lowest average value of 20 Bqm-3 was found in Hasilpur and Rahimyar Khan. In sitting moms the highest radon level of 43 Bq/m3 and 40 Bq/m3 was observed in Liaqatpur and Bahawalpur respectively whereas the lowest level of 26 Bq/m3 was found in Fort Abbas and Rahimyar Khan. The outdoor exhalation rate of radon was measured by closed can technique using N-85 and CR-39 detectors separately. With CN-85 detector the highest radon exhalation rate of 0.70Bq m-2h-1as found in Derawer Fort followed by 0.68Bq m-2h-1 in Rahimyar Khan whereas the lowest rate of 0.31Bq m-2h-1 was found in Bahawalpur. CR-39 detectors gave close results. The excess lung cancer risks Gue to indoor radon were determined in the seven towns based on the average radon concentration levels using EPA and UNSCEAR risk ,models. The highest values of29-102 and 38-114 Excess lung (cancer risks per MPY were found in the bedrooms of Liaqatpur using EPA and UNSCEAR risk models respectively. The lowest value of 12-43 and 16-49 Excess lung cancer risks per MPY were observed in the bedrooms of Hasilpur and Rahimyar Khan. In case of sitting rooms the trends were different.

Item Type:Thesis (PhD)
Uncontrolled Keywords:natural radioactivity, cancer, bahawalpur division, radon, ra, th, k, environmental radioactivity, cesium
Subjects:Physical Sciences (f) > Chemistry(f2)
ID Code:1031
Deposited By:Mr. Muhammad Asif
Deposited On:16 Dec 2006
Last Modified:04 Oct 2007 21:04

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