Radiological impact of dietary intakes of naturally occurring radionuclides on Pakistani adults

Daily dietary intakes of three naturally occurring long-lived radionuclides 232Th, 238U and 40K were estimated for the adult population of Pakistan using neutron activation analysis (NAA), inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), respectively. The daily intakes of 232Th ranged from 4 to 29 mBq, 238U ranged from 17 to 82 mBq and 40K ranged from 51 to 128 Bq. The geometric means of these intakes were 10 mBq d−1 for 232Th, 33 mBq d−1 for 238U and 78.5 Bq d−1 for 40K. The measured values give annual committed effective doses of 0.80, 0.53 and 178.75 μSv yr−1 for 232Th, 238U and 40K, respectively to Pakistani population. The net radiological impact of these radionuclides is 180.08 μSv yr−1. This value gives cancer risk factor of 4.5 × 10−4 and loss of life expectancy of 0.87 days only. Whereas ICRP cancer risk factor for general public is 2.5 × 10−3 and total risk involve from the all natural radiation sources based on global average annual radiation dose of 2.4 mSv yr−1 is 6.0 × 10−3. The estimated cancer risk shows that probability of increase of cancer risk from daily Pakistani diet is only a minor fraction of ICRP values. Therefore, the diet does not pose any significant health hazard and is considered radiologically safe for human consumption.