Ecotoxicological Risks of Improper Waste Management in Revers State Nigeria: A Comprehensive Review

Uncontrolled dumping, petrochemical effluent, and a high rate of industrialisation have led to the formation of a multifaceted toxic environment in Rivers State, Nigeria, underscoring improper waste management as a significant ecotoxicological challenge. The empirical and theoretical evidence have been synthesized in this study through a systematic narrative review of ninety-four peer-reviewed works (2010- 2024), based on the PRISMA framework, for contaminant loads, ecological risk indices, and toxicological pathways, which were used to evaluate toxicological pathways. The results indicated widespread heavy metal (Pb 45.2–178.5 mg/kg, Cd 2.1–8.4 mg/kg, Cr 50.6–132.2 mg/kg) and organic pollutants (Σ16PAH = 5.6–48.9 μg/L; PCBs 0.8–3.5 μg/L), or more than the WHO and USEPA safety limits. Risk assessment through the PERI and the Igeo index identified most sites as having a very high ecological risk (PERI > 600), especially in the industrial belts of Eleme and Trans-Amadi. Oxidative stress and evidence of oxidative damage and genotoxicity were exhibited by high levels of superoxide dismutase, catalase, and malondialdehyde activities in the biomarker assays across three sentinel species, and a case of hepatic necrosis and an inhibition of metabolism was confirmed in histopathological examination. The triangulated synthesis set up produced a synergistic toxicity between metals, hydrocarbons, and microplastics, destabilizing microbial consortia, distorting nutrient cycling, and bioaccumulating along food webs. All these effects indicate that Rivers State is in a multi-stressor ecotoxicological regime, where the mismanagement and poor enforcement of waste management exacerbate ecological vulnerability. This research concludes by suggesting biomarker-based precautionary educational structures, increased observation, geo-spatial hydrochemistry, and the incorporation of ecotoxicological indicators as policy instruments to support the establishment of risk-conscious waste management in accordance with the Basel Convention and the Sustainable Development Goals (3, 6, 12, and 15).