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The outdoor gamma dose rate was measured in 540 locations in southern regions (Ramanathapuram, Virudhunagar, Tirunelveli, and Thoothukudi) of Tamil Nadu, India. The measured dose rates vary from 35 to 335 nSv/h (mean 89 nSv/h). The observed mean dose rate (89 nSv/h) is 2.3 times higher than the national (India) average of 39 nSv/h (56 nGy/h) and 2.1 times higher than the world average of 41 nSv/h (59 nGy/h). Annual Effective Dose (AED) calculated varies from 0.04 to 0.41 mSv/y (mean 0.11 mSv/y). The mean AED (0.11 mSv/y) is 1.6 times higher than the world average annual effective dose of 0.07 mSv/y. 30% of the locations have higher AED values due to the higher radiation in that locations. The present study reveals that the Tirunelveli district of the southern Tamilnadu region has higher gamma radiation than the other four districts of this region and is due to the topography of coastal and mountainous areas in Tirunelveli. The higher gamma radiation dose in the study area is due to the radionuclides present in the mountainous region's rocks and the coastal regions' soils. The radiological maps were used for spatial interpretation of the outdoor gamma dose rate in the study area. The radiological cancer risk assessment reveals that the Tirunelveli district has a higher risk due to the higher background gamma radiation. [ABSTRACT FROM AUTHOR]

Pollution level and noncarcinogenic health risks due to fluoride and nitrate in the groundwater samples from Ramanathapuram district during pre-monsoon (September 2016) were calculated. One hundred and fifty-two groundwater samples collected were analysed for various physicochemical parameters such as major cations (Ca2+, Mg2+, Na+, K+) and major anions (CO32-, HCO3−, SO42-, Cl−, NO3−, PO43-). The fluoride ion concentrations in the collected samples were measured using the fluoride ion-selective electrode. Noncarcinogenic risks were calculated based on fluoride and nitrate concentrations (fluoride – 0.02–1.00 and nitrate – 0.0–4.9). The calculated risk values exceed the United States Environmental Production Agency (USEPA) recommended value of 1. The habitants from the study area are under the health risk due to fluoride and nitrate. Water quality index (WQI) values of the analysed samples indicate that 52% poor, 14% very poor, and 4% unsuitable for drinking purposes. Piper plot shows that 58% of mixed Ca2+-Mg2+-Cl− and 16% of Na+-Cl− groundwater types are predominant in the study area. Gibbs plot reveals that 91% of the samples have rock-water interaction, and it is a principal process that controls the dissolution of minerals from the subsurface into groundwater. Statistical analysis (correlation analysis, factor analysis) reveals that the natural process (rock-water interaction, leaching of sediments) and anthropogenic activities (domestic sewage, untreated effluents from industries) are the reason for the high fluoride and nitrate concentration in the groundwater. High noncarcinogenic health risk places were marked in spatial distribution maps. [ABSTRACT FROM AUTHOR]

The present investigation aims to determine the health risks of toxic uranium contamination in the drinking water of the Thoothukudi district. Two hundred and eighty-six samples were examined during the pre- and post-monsoon seasons and found the uranium concentration ranges from <0.2 to 167 ppb (mean 12, Standard deviation 21) (pre-monsoon) and <02 to 190 ppb (mean 13, Standard deviation 24) (post-monsoon). Geochemical modeling studies and the reducing nature of samples reveal that the uraninite mineral is under saturated conditions, and the least soluble U4O9 mineral species is predominantly distributed during both seasons. Statistical analysis provides that applying nitrogen and phosphate fertilizers may induce the dissolution of uranium minerals, which is responsible for elevated uranium in the collected samples. The calculated noncarcinogenic risk of uranium range from 0.005 to 8.09 (pre-monsoon) and 0.005 to 9.18 (post-monsoon). 15% (pre-monsoon) and 17% (post-monsoon) of the samples show a higher noncarcinogenic risk. The calculated cancer mortality and morbidity are within the permissible limit of 10−3, and the present health risk assessment of uranium is evident that the people from this district have the chemical toxicity of uranium than the carcinogenic risk due to drinking water. [ABSTRACT FROM AUTHOR]

The present investigation has been carried out in the Ottapidaram taluk to evaluate the suitability of groundwater for drinking purposes and to assess the non-carcinogenic health risks. Twenty groundwater samples were collected, and the major physicochemical parameters were measured along with the heavy metals lead (Pb2+) and chromium (Cr2+). The analyzed anions and cations follow the average dominance order, Cl− > PO43− > SO42− > NO3− > F−, and Mg2+ > Ca2+ > Na+ > K+, respectively. From the water quality index to know the 45% of the water samples are unsuitable for drinking purposes. The statistical analysis of the data infers that major geochemical process of the region is leaching of salts by contaminated water, followed by industrial pollution and geogenic sources. The spatial representation of the different parameters reveals that the western part of the study area is predominated by geogenic sources and the eastern part is contaminated by industrial effluents. The non-carcinogenic risks of F−, NO3−, Cr2+, and Pb2+ were assessed. The findings show 40% of the samples exceeds the chromium hazard quotient, and 50% exceed the lead hazard quotient value of 1 recommended by the US Environmental Protection Agency (USEPA). The present investigation shows that Cr2+ and Pb2+ highly pollute the groundwater due to the industrial impacts. The present study suggests that the groundwater from this taluk is worse, and people from this taluk have health risks due to groundwater drinking. [ABSTRACT FROM AUTHOR]