LEEROY SAKARIAS, DAVID KOLKOMA, FELIX BESLIN PEREIRA AND JOJO PANAKAL JOHN
Abstract
Soil is a potential source of direct radiation exposure to human beings from natural radionuclides. The exposure primarily occurs through the environmental gamma radiation and consumption of foodstuffs containing radionuclides. Primordial radionuclides and their progeny present in soil generally give higher radiation doses than those provided by artificially produced radionuclides. Bioaccumulation of these radioactive elements could be hazardous to human health. Therefore, it is necessary to evaluate the radionuclide levels in the surface soil and to estimate the resulting health hazards. Measurement of activity concentration of primordial radionuclides in soil samples collected from 40 locations in the Markham and Huon Gulf Districts of Morobe province in Papua New Guinea (PNG) were carried out. Gamma ray spectrometry using High Purity Germanium (HPGe) was used for analyses. The activity concentrations of 238U, 232Th, and 40K were found to vary widely. The average values of these nuclides in soil were 92±36 Bqkg-1, 18±14 Bq kg-1 and 492±130 Bq kg-1 respectively. Estimated radiological parameters due to radionuclides in soil relevant for human health namely external gamma dose (D), annual effective dose (AED) and excess lifetime cancer risk (ELCR) were 74±19 nGyh-1, 0.10± 0.02 mSv y-1 and 0.3±0.1 per 1000. The radiological parameters related radionuclides in soil were below the permissible limit and are not expected to pose any radiological health risk.