Thorium concentration in Pakistani diet

To evaluate radiation doses due to ingestion of thorium activity by members of the public, baseline analytical data on thorium concentration in a typical Pakistani diet was generated. Food samples were collected from major districts/ cities of the country using the market basket method, and typical daily diets were prepared. Thorium concentration was determined by instrumental neutron activation analysis. It was found to vary from 1.6 ng g(-1) to 12 ng g(-1). The median value was 4.6 ng g(-1). This leads to median daily thorium intake of 2.7 microg d(-1). The geometric mean was 2.6 microg d(-1), which was 13% less than the ICRP value. Based on these measurements the average intake of 232Th activity was 10 mBq d(-1), and the average annual and committed effective doses for adults were estimated to be 8.8 x 10(-7) Sv y(-1) and 4.4 x 10(-5) Sv, respectively.