Occupational radiological risk assessment and quantification of natural radionuclides present in Pakistani coal

In this study, 47 coal samples from 16 selected coal mines from four provinces of Pakistan (Punjab, Sindh, Balochistan, and Khyber Pakhtunkhwa) were collected and analysed using a HPGe-based gamma spectrometry system. The objective of the study was to assess the occupational radiological risk from coal reserves in Pakistan. The Ra-226 concentration values were found to be higher in coal samples collected from two locations in Meting-Jhumpir Coal Fields and one location of Chakwal Coal Field as compared to the recommended value by UNSCEAR (2000). The Th-232 concentration values were found to be higher in coal samples collected from two locations in Padhrar Coal Field, one location in Dandot Coal Field and one location in Cherat Coal Field as compared to the recommended value by UNSCEAR (2000). The K-40 values in all the analysed samples were found to be well below the recommended value by UNSCEAR (2000). From the radiological parameters, the values of the representative gamma index, which corresponds to an annual effective dose, were found to be higher than 1 Bq-kg(-1 )among the samples collected from Meting-Jhumpir coal fields, Chakwal coal field, Padhrar coal fields, Dandot coal fields, Hangu coal field, and Cherat coal fields. Excess lifetime cancer risk was estimated to be in the range of 0.07 x 10(-3) - 0.34 x 10(-3) with an average value of 0.18 x 10(-3). The annual effective dose was estimated in the range of 0.01-0.07 mu Sv- y(-1), which is below than the value established by the IAEA as the safe limit for the public in a planned exposure situation (1 mSv-y(-1)). It can be concluded that for some of the coal fields, the radionuclide concentration values and some of the radiological parameter values were found to be higher than the recommended values. Site-specific studies using direct radiation and radon measurement instruments are proposed for these coal fields to further investigate the radiological situation and its implications on workers and the public's health. Furthermore, we have used a theoretical approach to estimate the occupational health hazard based on the activity concentration of radionuclides in the coal samples, which needs to be validated with the direct-dose measurement techniques.