Assessment of Heavy Metal and Agricultural Pesticide Bioaccumulation in Freshwater Fish Species of South Dinajpur District, West Bengal

Abstract

Freshwater fish occupy a critical position at the intersection of aquatic ecology, rural livelihoods, and food security in eastern India. In agrarian districts such as South Dinajpur in West Bengal, fish are embedded within floodplain rivers, kharis, beels, ponds, and culture-based systems that are increasingly exposed to agricultural runoff, sediment-bound contaminants, and diffuse anthropogenic inputs. Although substantial literature documents heavy metal contamination and pesticide residues in freshwater fishes across India, and several studies from the lower Gangetic and wider West Bengal region demonstrate measurable contaminant burdens in edible species, the evidence remains fragmented. Most published studies examine either heavy metals or pesticides, focus on a restricted set of species, or neglect the ecological and landscape processes that mediate contaminant uptake. A district-focused synthesis for South Dinajpur is lacking.

This review critically synthesizes peer-reviewed literature and relevant policy documents to examine how heavy metals and agricultural pesticides may accumulate in freshwater fish species inhabiting the fluvial and wetland mosaic of South Dinajpur District. The article is guided by a landscape ecotoxicology framework that links land use, hydrological connectivity, sediment dynamics, fish ecology, and human dietary exposure. It argues that South Dinajpur represents a high-priority but under-studied freshwater risk landscape because it combines intensive agriculture, floodplain hydrology, river-beel connectivity, and dependence on locally harvested fish. Evidence from India and the lower Gangetic region indicates consistent patterns of species-specific, tissue-specific, and site-specific bioaccumulation; recurrent concern for Pb, Cd, Cr, Hg, DDT derivatives, HCH isomers, endosulfan, and organophosphate residues; and growing relevance of human health risk metrics such as estimated daily intake, target hazard quotient, and carcinogenic risk.

The article contributes to knowledge in three ways. First, it integrates metal and pesticide literatures that are often treated separately. Second, it develops a district-sensitive conceptual model for understanding contaminant movement from agricultural landscapes to fish tissues and, ultimately, to human consumers. Third, it proposes a research agenda for South Dinajpur that prioritizes mixed-contaminant surveillance, species ecology, seasonality, sediment linkage, and food safety governance. The review provides a basis for journal publication, field study design, and policy discussion on freshwater fish safety in eastern India.