RADON MONITORING IN GROUNDWATER SAMPLES FROM SOME AREAS OF NORTHERN RAJASTHAN, INDIA, USING A RAD7 DETECTOR Asha Rani 1, *, Rohit Mehra 2 and Vikas Duggal 3 1 Department of Applied Sciences, Adesh Institute of Engineering and Technology, Faridkot 151203, India 2 Department of Physics, Dr. B.R. Ambedkar National Institute of Technology, Jalandhar 144001, India 3 Department of Applied Sciences, Punjab Technical University, Jalandhar 144001, India *Corresponding author: ashasachdeva78@gmail.com Received January 24 2012, revised June 23 2012, accepted June 26 2012 Radon monitoring has been increasingly conducted worldwide because of the hazardous effects of radon on the health of human beings. In the present research, groundwater samples were taken from hand pumps at different areas of the districts of SriGanganagar, Hanumangarh, Sikar and Churu in northern Rajasthan. RAD7, an electronic radon detector (Durridge co., USA), was used to estimate the radon concentration in groundwater used for drinking. Radon concentration in the ground- water ranged from 0.5 + 0.3 Bq l 21 (Chimanpura) to 85.7 +4.9 Bq l 21 (Khandela) with an average value of 9.03 +1.03 Bq l 21 . In 89 % of the samples, radon concentration is well below the allowed maximum contamination level (MCL) of radon concen- tration in water of 11 Bq l 21 , proposed by US Environmental Protection Agency (USEPA). Only in 11 % of the samples, the recordedvalues were found to be higher than MCL proposed by USEPA and only in 5 % of the samples, the recordedvalues were found to be higher than the values between 4 and 40 Bq l 21 suggested for radon concentration in water for human con- sumption by the United Nations Scientific Committee on the effect of Atomic Radiation (UNSCEAR). The annual effective dose in stomach and lungs per person was also evaluated in this research. The estimated total annual effective dose of adults ranged from 1.34 to 229.68 mSv y –1 . The total annual effective dose from three locations of the studied areawas found to be greater than the safe limit (0.1 mSv y –1 ) recommended by World Health Organization and EU Council. INTRODUCTION 222 Rn, a noble radioactive gas produced by decay of 226 Ra, is a member of the 238 U series, and uranium, a source of radon, is present in almost all types of rocks, plants and groundwater. Natural water contains dissolved radon from the uranium series present in soil and rocks (1) . Radon gas and its radio- active isotopes have special attention among all other naturally occurring radioactive materials, because it has the largest amount of total annual effective dose to human (2, 3) . Dissolved radon is easily released into the air when thewater is used for showering, cleaning and other everyday purposes in homes. Only about 1–2 % of radon in the air comes from drinking water. However, breathing radon released to air from tap water increases the risk of lung cancer. Some radon stays in the water; drinking water containing radon also presents a risk of developing internal organ cancers, primarily stomach cancer. However, this risk is smaller than the risk of developing lung cancer from radon released to air from tap water. Based on the report of National Academy of Science, the United States Environmental Protection Agency (USEPA) estimates that radon in drinking water cause about 168 cancer deaths per year, 89 % from lung cancer cause by breathing radon released to the indoor air from water and 11 % from stomach cancer caused by consuming water containing radon (4) . USEPA has proposed that the allowed maximum contamination level (MCL) for radon concentration in water is 11 Bq l 21(5) . The purpose of this study was to investigate the radon concentrations of groundwater used for drinking in some areas of northern Rajasthan. GEOLOGY OF THE STUDIED AREA Rajasthan is located in northwest of India. Figure 1 shows the geographic location of the state of Rajasthan, as well as the location of the sampling sites. The studied area is bounded on the western side by Pakistan, on the northeast side by the state of Haryana and to the north by the state of Punjab. Sriganganagar and Hanumangarh districts have a plain surface covered with a thick layer of allu- vium and wind-blown sand. The Ghaggar river is an ephemeral one and has a northeast-to- southeast course near Hanumangarh and divide the Ganganagar district into two halves. The Churu dis- trict is a part of the Thar desert. The Soil of the Churu district is pale brown, single grained, deep and well drained. The soils of the Sikar district are predominantly light textured, weak structured well drained alluvial and eolian in nature. Most of the # The Author 2012. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com Radiation Protection Dosimetry (2012), pp. 1–6 doi:10.1093/rpd/ncs130 Radiation Protection Dosimetry Advance Access published July 22, 2012 by guest on July 23, 2012 http://rpd.oxfordjournals.org/ Downloaded from