To enhance the radiation protection infrastructure and food hygiene in Pakistan, radiological and nutritional aspects of diet were studied through daily elemental intake. Food samples were collected from various ecological areas of the country on market basket method and typical daily diets were prepared. Daily dietary intakes of 7 radiologically important elements (Cs, Th, U, I, Sr, Ca and K) and 7 nutritionally important elements (Fe, Zn, Se, Cr, Mg, Na and Mn) were estimated by using well-known nuclear analytical techniques i.e. NAA, AAS, ICP-AES, ICP-MS etc. as 1st and 2nd priority elements, respectively. Baseline analytical data on these elements have been generated for the detection of any nuclear emergency in the country and its effective handling.
The measured average concentrations of these elements are cesium: 10.4 ng g-1; thorium: 5.1 ng g-1; uranium: 5.2 ng g-1; iodine: 80.1 ng g-1; strontium: 4.9 µg g-1; calcium: 0.86 mg g-1; potassium 4.5 mg g-1; iron 52.4 µg g-1; zinc 22.9 µg g-1; selenium 0.2 µg g-1; chromium 0.2 µg g-1; magnesium: 0.8 mg g-1; sodium: 0.5 mg g-1 and manganese: 17.9 µg g-1. These levels lead to average daily dietary intake of cesium: 6.2 µg thorium: 3.0 µg; uranium: 3.1 µg; iodine: 47.3 µg, strontium: 2.9 mg; calcium: 0.51 g; potassium: 2.7 g; iron: 31.0 mg; zinc: 13.6 mg; selenium: 110 µg; chromium: 130 µg; magnesium: 0.50 g and manganese: 10.6 mg.
Estimated intake values of these elements are compared with the recommended values of International Committee of Radiological Protection (ICRP), World Health Organizations (WHO) and recommended Food Dietary Allowance (FDA) for reference man. Radiological impact due to ingestion of observed radionuclides (i.e. 232Th, C 238U and 40K) on Pakistani adults has been estimated, using dose coefficients of ICRP standard models. The annual intake of thorium, uranium and potassium activities are 3.65, 12 and 2x104 Bq, leading to annual effective dose of 0.80, 0.53 and 178.75 µSvy-1, respectively. The net impact of all these radionuclides is 180.08 µSvy-1. The results reveal that the major contributor to radiation dose is 40K only, whereas activities of 232Th, 238V are comparatively negligible.
Comparison of the net dose with the available published results shows that our values are comparable with annual world average ingestion dose of 180.32 µSV from these radionuclides. Whereas it is-13 times less than the global average values of 2.4 mSv from all sources and 5.5 times less than ICRP recommended limit of 1 mSv for general public. Cancer risk factor from measured annual dose of 180.08 µSv for adult person is estimated as 4.5 x 10-4. Whereas ICRP cancer risk factor for general public is 2.5 x 10-3 and total risk involve from the all natural radiation sources based on global average annual radiation dose of 2.4 mSv is 6.0 x 10-3. The estimated cancer risk factor shows that probability of increase of cancer risk from daily Pakistani diet is only a minor fraction of ICRP values. The risk of cancer from measured radiation in term of loss of life expectancy is also estimated. It is 0.87 days. Whereas risks associated with other activities of normal daily life such as smoking, overeating and drinking are 6 years, 2 years and 1 year, respectively. The estimated values depict no significant radiological health impact.
Food safety and adequacy of radiologically important elements (U, Th, K, I, Cs, Sr and Ca and essential elements (Mg, Na, Fe, Mn, Se, Zn and Cr) have been assessed. Comparison of measured values of these elements with the recommended safe limits reveals that our diet is enriched with majority of the essential nutrients Fe, Zn, Mg, Sr, Se, Cr, Na, Mn, while it is deficient in I and Ca. The nutritional status of the daily diet is estimated as 2515 kcal d-1.
The results show that our diet is radiologically safe and has no significant health detriment. Its food hygiene is good and comparable with the international standards. However, deficiency of some essential elements iodine and calcium demands remedial measures and improvement of dietary habits.