Abstract
The Khewera Mines located in Pakistan contain the world's second largest reserves of rock salt. Rock salt is used in Pakistan in food recipes. It was decided to investigate the concentrations of naturally occurring radionuclides in rock salt from the Khewera Mines. Samples of rock salt were collected from 10 different locations and analysed by gamma spectrometry. The mean activity concentrations of super(226)Ra, super(232)Th and super(40)K were 790 c 262, 640 c 162 and 23 000 c 6000 mBq kg super(-1), respectively. The mean annual effective dose due to the intake of natural radionuclides from rock salt for adults was estimated to be 0.0638 c 0.015 mSv, which is lower than the average annual effective dose of 0.29 mSv received per caput worldwide due to the ingestion of natural radionuclides, as reported by the United Nations Scientific Committee on the Effects of Atomic Radiation in 2000.