Abstract
Naturally occurring radionuclides are always present in groundwater used for drinking and cultivation purposes. Intake of these radionuclides through ingestion of drinking water results in radiation doses to humans, which may cause radiological health hazards. This article presents the results of measured concentrations of naturally occurring radionuclides of 226Ra, 232Th, and 40K in municipal supply drinking water in metropolitan Lahore city of Pakistan and an evaluation of consequent gamma radiation doses to the consumers. Multiple water samples were collected from all nine municipal towns of Lahore city of Pakistan and analyzed using gamma spectrometry technique. Mean concentrations of 226Ra, 232Th, and 40K in water samples were of the order of 104 35, 69 17, and 625 85 mBq l- 1 respectively. Mean annual effective radiation doses due to ingestion of all three natural radionuclides from intake of drinking water for age groups of 2-7, 7-12, 12-17 and 17 years (adults) were evaluated, which were found below the World Health Organization (WHO) (Geneva, Switzerland) recommended limit of 0.1 mSv y- 1. It was observed that as pH increases, concentrations of 226Ra and 232Th decrease in water samples. However, a linear positive correlation was found between 226Ra concentration and water chemical parameters such as, total dissolved solids (TDS) and sulphates content. Data generated in this study may be helpful in establishing background levels of natural radionuclides in drinking water that could be used to distinguish additional contributions when a contamination event occurs in future, as well as, for inception of safety standards by the concerned authorities to maintain radioactive contamination free drinking water supplies for the general public.