EVALUATION OF INDOOR/OUTDOOR GAMMA EXPOSURE RATES AND EXCESS LIFE TIME CANCER RISK IN DIFFERENT CITIES OF PAKISTAN

STUDIES ON GAMMA DOSE RATES IN OUTDOOR ENVIRONMENT AND ASSESSMENT OF EXTERNAL EXPOSURE TO PUBLIC IN STEPNOGORSK AREA, NORTHERN KAZAKHSTAN

The present study is based on a pilot study, which showed that the Stepnogorsk area of Northern Kazakhstan represents sources of potential contamination of the living environment. The aim of the study was measurement of outdoor gamma radiation levels, activity concentration in soil samples and assessment of external exposure to the public. According to our analysis, the highest ${\boldsymbol{H}}^{\ast}$(10) values ∼2870 nGy h-1 were detected in the Aqsu school territory, which were slightly higher than the control readings for this region. The average 226Ra, 232Th and 40K activities were 617.8 ± 3.2 Bq kg-1, 188.3 ± 2.9 Bq kg-1 and 731.5 ± 6.2 Bq kg-1, respectively. The annual effective dose received by the Aqsu population ranged from 0.08 to 3.5 mSv y-1, which was found higher by an order of magnitude than the upper annual dose limit. Changes in radiation background are an unfavourable factor for the population and may possibly become potential radiation risks for long-term effects.

Soil mineral analysis and environmental radioactivity in Ghizer, Eastern Hindukush, Pakistan

Distribution of natural and anthropogenic radionuclides (226Ra, 232Th, 137Cs and 40K) was determined in 32 samples from Ghizer, an Eastern Hindukush district at an altitude of 2286 m in Pakistan using high resolution gamma-ray spectrometry. Mineralogical analysis by X-ray diffractometry identified quartz, calcite, albite and anorthite as major phases whereas actinolite, chlorite serpentine and kaolinite as minor phases. The activity concentrations for 226Ra, 232Th, 137Cs and 40K varied from 25.2 ± 1.7 to 145.3 ± 10.1 Bq kg−1, 24.9 ± 1.1 to 197 ± 9 Bq kg−1, 2.03 ± 0.21 to 16.7 ± 1.1 and 252 ± 6 to 1433 ± 35 Bq kg−1, respectively. The samples yielded average radium equivalent activity as 178.4 ± 23.3 Bq kg−1. The majority of the samples revealed external hazard index and representative level index less than one. The average air absorbed dose rate was 91.2 ± 13.6 nGy h−1 corresponding to the annual effective dose rate 111.8 ± 17.4 μSv y−1. These values were higher than the world averages for air absorbed dose rate and outdoor annual effective dose rate. Principal component analysis was applied to obtain distribution pattern within the samples and among the radionuclides.