Abattoir waste in Sokoto State, Nigeria: Pollution Pathways, Public Health Risks and Management Options at the Environment-Animal-Human Interface

Abattoirs are essential for a safe meat supply but, in much of Nigeria, they operate without effective waste treatment. This narrative review synthesises evidence on the composition of abattoir wastes, the pathways through which they reach water, air, soil and food, and the associated risks to animal, human and environmental health, and it appraises management options suited to low-resource settings. Evidence was identified through targeted searches of publisher platforms, PubMed Central, African Journals Online and the Directory of Open Access Journals, supplemented by citation tracking. Blood and paunch contents are the most oxygen-demanding streams, with reported chemical oxygen demand of the order of 10 5 mg/L, and solid waste is commonly piled, dumped or burnt in the open. Nigerian studies document pollution of receiving rivers, a documented burden of abattoir-associated zoonoses, and multidrug-resistant Escherichia coli and Salmonella in food animals and animal-derived products. Worker exposure to zoonoses is plausible and documented, but evidence on health outcomes among surrounding residents is sparse and rarely based on comparative designs. Treatment technologies developed for industrial slaughterhouses (anaerobic digestion, nutrient removal and advanced oxidation) are well characterised, yet validated low-cost implementations in Nigeria are scarce. We propose a tiered management pathway (source segregation, drainage control, anaerobic stabilisation with resource recovery, and polishing before discharge) and a research agenda centred on standardised effluent characterisation, antimicrobial-resistance surveillance, exposure–outcome studies and economic evaluation. Aligning enforcement, local-government operation and community engagement is as important as technology.