Assessing Variability and Hydrochemical Characteristics of Groundwater Fluoride Contamination and its Associated Health Risks in East Singhbhum district of Jharkhand, India.

In many regions of the world, groundwater is the main supply of high-quality drinking water [1]. Widespread discharge of contaminants has negatively impacted groundwater quality, depending on the level of recharge, degree of precipitation, rock dissolution, and geography [2]. Fluoride pollution is becoming a global concern for environmental health [3], [4], [5], [6]. Fluoride ions (F^–) are one of the most common pollutants found in water and can enter the human body. A requisite concentration of fluoride content in water is essential for reinforcing tooth enamel strength, rendering it resistant to decay and acid attacks. Simultaneously, an optimal fluoride concentration is pivotal for facilitating growth, development, and bone metabolism. The fluoride concentration, a modest level of around 0.60- 0.80 mg/L yields benefits to human health [7]. However exceeding 1.5 mg/L, becomes a hazard [7], [8]. Consumption of fluoride above the permissible limit can result in skeletal and dental fluorosis, a condition capable of calcifying ligaments and causing teeth to mottle, reproductive problems, and developmental delays in children [9]. The impact of fluoride consumption extends to neurological disorders, chronic pregnancy-related issues, diminished childhood intelligence, and muscular fatigue [10]. Consuming vegetables and crops enriched with fluoride has been revealed to cause a chronic harmful effect on the bodies of humans and animals who eat soil contaminated with fluoride [11], [12]. Alarming reports indicate that excessive fluoride ions in groundwater imperil the well-being of over 260 million individuals globally [13]. India, particularly faces the challenge of fluorosis across 21 states, affecting approximately 66 million people [14]. A prevalent concern is the contamination of groundwater by fluoride through anthropogenic activities and natural processes [15], [16]. Anthropogenic sources are due to human developmental activities, domestic and industrial waste water effluent, agricultural and urban runoff, while geogenic sources result from water-rock interactions, leading to the release of substantial fluoride through the disintegration of fluorine-bearing minerals [17]. Significantly, it has been discovered that higher fluoride concentrations in groundwater are linked to the decomposition of fluoride-rich minerals within underlying rocks, as supported by the study conducted [18]. The dissolution of fluoride-bearing compounds, encompassing minerals like sellaite (MgF₂), cryolite Na₃(AlF₆), fluorite (CaF₂), topaz (Al₂(SiO₄) F₂), mica (K(Li,Al)₃(AlSi₃O₁₀)(O,OH,F)₂), muscovite (KAl₂(AlSi₃O₁₀)(F^?,OH)₂), fluorapatite (Ca₅(PO₄)₃F), and crystalline igneous rocks plays an important role in releasing fluoride from geological formations [17], [19], [20]. High sodium (Na⁺) and bicarbonates (HCO₃^–) in groundwater accelerate the rate of dissolution of fluoride within F^– bearing substances as a result of water-mineral action [21]. The dissolution of fluorite, often accompanied by calcite precipitation, has been identified as a contributor to increased fluoride concentrations in groundwater [22], [23]. In dry climates with high evaporation rates and through mixing processes, factors contribute to an enhancement of fluoride concentrations in groundwater [24]. Previous research on fluoride has been published to investigate its causes and distribution globally [4], [25], [26], [27], [28], [29], [30]. The fluoride levels in East Singhbhum, India, are likely due to a combination of factors, including the geology of the area, the presence of mining activities, and the lack of effective water techniques. This study was performed for the first time in a district of Jharkhand state which states the fluoride concentration in ground water bodies of study area. No researchers had previously performed any such study which could have mentioned the presence and impacts of fluoride on humans in one of the important industrial places of Jharkhand state. The main objectives of this study are: (1) to determine fluoride contamination in groundwater of East Singhbhum district within a prominent mining zone, including potential sources; (2) assessing the non-carcinogenic health risks associated with F^– across three age groups (adults, children, infants); (3) groundwater quality has been assessed through analysis of correlations among various water parameters. This study aims to reveal the minerals and hydrogeochemical processes that contribute to elevated F^? concentrations in groundwater. This study provides the first comprehensive assessment of the distribution and presence of fluoride in groundwater in 11 blocks of East singhbhum, highlighting potential human health risks. Current study was performed keeping that in mind, and it would work as a guideline for state administrative and future researchers working in this area.