Concentrations of Natural Radionuclides in Municipal Supply Drinking Water and Evaluation of Radiological Hazards

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.

Keywords:

• natural radionuclides
• drinking water
• gamma spectrometry
• radiological hazards

Acknowledgement

The authors are thankful to the anonymous reviewers whose suggestions have helped a lot in reaching to the final version of thisarticle. Thanks are also due to the Water and Sanitation Agency (WASA), Lahore, Lahore Development Authority (LDA) and Metropolitan City District Government. Lahore for cooperation and providing services of concerned staff in all nine municipal towns during the sampling work conducted.