E-Waste Toxicants in Nigeria: Multi-Pathway Exposure, Toxicological Mechanisms, Human Health, Ecological Consequences and Management Priorities

Abstract

Electronic waste (e-waste) is a rapidly growing, chemically complex waste stream that poses interconnected environmental, occupational, and public-health challenges. Nigeria generated approximately 500 kt of e-waste in 2022, making it one of Africa’s major generators. Although informal recycling provides economic benefits, unsound dismantling, burning, and disposal can release toxic metals, PAHs, PCBs, flame retardants, dioxins, furans, plasticizers, and other hazardous substances. This review synthesizes evidence on their occurrence, environmental fate, exposure pathways, toxicological mechanisms, human-health effects, ecological consequences, and management implications in Nigeria. Contaminants have been detected in soil, dust, water, sediment and vegetation, with exposure occurring through inhalation, ingestion, dermal contact, dietary transfer, occupational activities and maternal–infant pathways. Evidence is strongest for environmental contamination and metal-associated risks, while longitudinal evidence linking exposure to chronic disease remains limited. Toxicological mechanisms include oxidative stress, genotoxicity, inflammation, endocrine disruption, mitochondrial dysfunction, and neurotoxicity. Ecological concerns include phytotoxicity, microbial impairment, aquatic contamination, bioaccumulation, and food-web transfer. Despite stronger regulation and extended producer responsibility, implementation and integration into the informal sector remain challenges. Future research should emphasize longitudinal biomonitoring, mixture toxicology, bio accessibility, ecological effects, and regulatory evaluation within a One Health and circular economy framework.