Microplastic Distribution and Characterization in Nigerian Semi-Urban Environments: A Case Study of Orji and Obinze

Microplastics (MPs), plastic particles <5 mm, are a newly potential source of contamination in semi-urban areas in Nigeria. In this computational modeling research, we evaluated MP distribution, characterization, and risk in Orji and Obinze, Imo State, based on machine learning and statistical analysis of recent environmental data in Nigeria (2023-2025). Weibull models yielded the means of 425 particles/kg in Orji and 380 particles/kg in Obinze as polyethylene (39%) polypropylene (35-44%) were the predominant polymers. The results of random forest models (R 2 = 0.87) reflected substantial polycyclic aromatic hydrocarbons and lead attachment, thus realizing ecological risk quotients of 3.1-3.3 beyond safety objectives. There are estimates of HUMAN ingestion (0.2-0.6 mg/kg/day) which approach levels of concern. This paper is the first to quantitatively measure the extent of MP contamination in semi-urban settings in Nigeria, that is informing waste management-related interventions related to Sustainable Development Goals 11 and 14 in particular.