###### Abstract  
In the modern era, due to the rapid increase in urbanization and industrialization in the vicinity of the Himalayas, heavy metals contamination in soil has become a key priority for researchers working globally; however, evaluation of the human and ecological risks mainly in hilly areas remains limited. In this study, we analyzed indices like the contamination factor (CF), degree of contamination (DC), enrichment factor (EF), geochemical index (Igeo), pollution ecological risk index (PERI), and pollution load index (PLI), along with cancer risk (CR) and hazard indices (HI), to ascertain the eco-environmental and human risks of using heavy metals in datasets collected from 168 sampling locations in Uttarakhand, India. The evaluation calculated of Igeo, EF, and CF suggests that represented soil samples were moderately contaminated and highly augmented with Rb, while PERI (75.56) advocates a low ecological risk. Further, PLI and DC (PLI: 1.26; DC: 36.66) show a possible health risk for the native population in the vicinity of the studied catchment. The hazard index (HI) is estimated greater than 1 (HI \(>\) 1) for Cr and Mn, representing a possible risk for cancer. However, adults are free from cancer risk, and other studied elements have been reported as noncarcinogenic. This assessment gives important information to policymakers, environmentalists, and foresters for taking mitigation measures in advance to mitigate the potential future risk of soil pollution on humans, ecology, and the environment. risk; heavy metal; human health; pollution indices; soil +
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run-off, wastewater, sewage, and effluent, and has become a common but intense issue in various ecosystems [13; 15; 16; 17; 18]. These environmental problems are widespread in India [19; 20; 21; 22]. Generally, long-term exposure to heavy metals profoundly creates health risks. Nonetheless, heavy metals do not show any adverse effect on human health and the environment if they are present at safe levels. If the concentrations of heavy metals exceed the safe limits, then they often cause acute health risks to mankind with severe consequences [9; 10; 16]. There are some trace elements that are essential for humans, such as iron, manganese, zinc, aluminum, lead, and cadmium; however, they may exert toxicity under pathological or artificially harsh conditions of exposure to excess levels [9; 10; 11; 23; 24], and references therein [25; 26; 27; 28; 29]. Soil characteristics are of considerable importance in holding the fertility of soil and balancing the nutrients requirements of different food chains [30]. The key information and mechanistic understanding of the outcome of various trace metals [31] and their dynamics are still under investigation in various ecosystems [32]. Furthermore, agriculture and the urban management of soil force change in the soil structure, function, and pedological properties [3; 33; 34]. In view of this, screening tools such as spectroscopic techniques (X-ray fluorescence (XRF)) and infrared diffuse reflectance techniques to understand the possible change in soil properties have been developed in recent years [35; 36] and are used to investigate the elemental composition of the soil [37; 38]. In this direction, important indices such as the cancer risk (CR), enrichment factor (EF), contamination factor (CF), geochemical index (I\({}_{\text{geo}}\)), and hazard indices (HI) have also been used for quantifying the soil contamination and risk to the eco-environment and human health at regional and/or global levels [9; 10; 34; 39; 40; 41]. Assessment of these important indices needs the existing background concentration (BC value) of individual heavy metals in the earth's crust. Thus, investigation for the assessment of the background concentration of these heavy metals in local/regional, national, continental, and global soils under different land-use systems was established [42; 43; 44; 45; 46; 47; 48; 49].