Nutritional Benefits, Trace-Element Bioaccumulation and Dietary Exposure Associated with Consumption of Chela cachius from the Sone River, Bihar: An Integrated Risk–Benefit Assessment

Nutritional Benefits, Trace-Element Bioaccumulation and Dietary Exposure Associated with Consumption of Chela cachius from the Sone River, Bihar: An Integrated Risk–Benefit Assessment Shagufta Perween Dr. (Prof.) Farida Bano Small indigenous fish species constitute an important source of affordable animal protein and micronutrients for river-dependent communities, but their consumption may also provide a dietary pathway for exposure to environmentally derived contaminants. This study evaluated the nutritional benefits, trace-element bioaccumulation and dietary exposure associated with consumption of Chela cachius from the Sone River, Bihar, using an integrated environmental–nutritional–toxicological risk–benefit framework. The investigation was conducted over 12 consecutive months (March 2025–February 2026) at five sampling sites representing an upstream-to-downstream anthropogenic gradient around Dehri-on-Sone, Rohtas District. Water quality was monitored monthly, while 450 adult C. cachius specimens were examined across three hydrological phases. Physicochemical characteristics were assessed using standard analytical procedures, and arsenic (As), lead (Pb), cadmium (Cd), mercury (Hg) and chromium (Cr) were quantified in water and fish tissue by atomic absorption spectrophotometry. Whole-body fish samples were evaluated for proximate composition, minerals, vitamins, amino acids and fatty acids. Dietary consumption was assessed among 150 river-dependent residents using repeated dietary recalls and food-frequency questionnaires, and contaminant exposure was estimated using estimated daily intake (EDI), target hazard quotient (THQ) and cumulative hazard index (HI). Marked spatial and seasonal variation in water quality was observed, with deterioration towards urban-influenced and downstream sites. Dissolved oxygen declined from 7.26 ± 0.77 mg L⁻¹ at the upstream reference site to 4.99 ± 0.60 mg L⁻¹ at S4, while pre-monsoon Pb concentration in water reached 19.50 µg L⁻¹ at S4. C. cachius contained 15.59–16.64% protein and 3.17–3.86% fat, together with substantial concentrations of calcium (833.0 ± 42.5 mg/100 g), phosphorus (606.0 ± 31.2 mg/100 g) and vitamin B12 (4.84 ± 0.48 µg/100 g). Essential amino acids represented approximately 43.2% of total amino acids, while PUFAs constituted 39.08 ± 2.68% of total fatty acids. EPA and DHA contributed 9.98 ± 0.94% and 15.39 ± 1.40%, respectively. Trace-element concentrations in fish tissue increased along the contamination gradient, with pre-monsoon Pb and Cd at S4 reaching 0.342 and 0.058 mg kg⁻¹, respectively. Individual THQs remained below unity, whereas cumulative HI exceeded unity at several urban and downstream sites, reaching 1.388 among children at S4 and a maximum pre-monsoon value of 1.632. The findings demonstrate that C. cachius provides substantial nutritional benefits while simultaneously representing a potential pathway for cumulative trace-element exposure. A spatially and seasonally targeted risk–benefit approach is therefore recommended, combining protection of the nutritional value of small indigenous fisheries with improved contaminant surveillance and river-pollution control.