The quantum of uranium in the groundwater of Thummalapalle, in Kadapa district, is below the maximum limit prescribed by the World Health Organisation (WHO) and therefore does not pose an immediate risk to people living in the area, concluded a team of researchers. Thummalapalle has one of the largest uranium resources in the world. Researchers from Jawaharlal Nehru Technological University (JNTU), Anantapur, Health Physics Unit of Nuclear Fuel Complex, Hyderabad, and Environmental Assessment Division of BARC, Mumbai conducted the study. The study gains significance as Uranium Corporation of India Limited (UCIL) has been carrying out uranium mining operations at Thummalapalle, its only uranium mill in south India. In the backdrop of UCIL's operations, researchers collected about two dozen groundwater samples from Thummalapalle and surrounding villages. The samples spanned 12 months covering both pre-monsoon and post-monsoon periods. According to Prof Suggala V Satyanarayana, the uranium concentration in ground water varied slightly between pre-monsoon and post-monsoon months, with summer period recording high concentration of this radioactive element. However, the average reading was below the WHO guideline value of 30 micro-grams per litre of water, he said. "We conducted background concentration of natural uranium and other physicochemical parameters in drinking water around Thummalapalle uranium mining and milling site. Water samples from 24 locations showed uranium concentration ranging between 2 micro-grams per litre and 34 micro-grams per litre during summer. Over all, it was below 30 micro-grams per litre prescribed by the WHO," Prof Satyanarayana told TOI. Prof Satyanarayana said they also conducted studies on other parameters like pH value and electric conductivity of water, and total dissolved solids present in the samples. At some places, the water samples showed higher pH values due to presence of sulphate, nitrates, and phosphate. . In case of TDS too, many locations had higher values than the value (500 mg per litre) fixed by the WHO. The TDS crossed 1500 mg per litre at places. "The variation of uranium levels in ground water may be due to the different concentrations of natural uranium in earth in and around the mining location," Prof Satyanarayana pointed out, adding that there is no remarkable change in the levels of uranium during rainy season and summer. Around 96 per cent of water samples analysed contained uranium below the WHO norms, he said.