Occurrence and Hazard Ranking of Microplastics in Owabi Headworks in the Ashanti Region of Ghana

The widespread use of plastics has resulted in environmental pollution by microplastics—tiny plastic fragments measuring between 1 µm and 5 mm. These particles are produced through physical, oxidative, or photochemical breakdown of larger plastics and can interact with different parts of the environment. Their presence in water bodies raises global concerns due to potential risks to ecosystems and human health. This study investigated microplastics in the water and sediments of the Owabi Headworks in Ghana, focusing on identifying the types and ranking their potential hazards based on factors such as polymer waste generation, density, degradation rate, particle size, and monomer composition. Four types of microplastics were detected—LDPE, HDPE, PET, and PP—with low levels ranging from 2–6 particles/L, and 2–4 particles/100 g recorded in water and sediment respectively, pointing to a source of pollution. Risk assessment using the baseline model showed that the toxicity ranking of risk factors was: global waste generation > density in freshwater > lifespan > chemical composition > particle size. Under different scenario models, the overall toxicity order of microplastics to human health and ecosystems was: HDPE > PET > LDPE > PP. This study found extremely low levels of microplastics in the study area, but highlighted the importance of regularly monitoring microplastic pollution at the headworks due to the increasing use of plastics, and suggests employing diverse risk assessment methods in future studies to better understand their potential impacts.