Why Nigeria should ban single-use plastics: Excessive microplastic pollution of the water, sediments and fish species in Osun River, Nigeria

The Osun River serves as a source of drinking and domestic water for some communities in Osun State Nigeria, in addition to providing a source of “healing water” for the worshippers of the Osun goddess. The sacred river has earned the status of a UNESCO world heritage centre for the worldwide attention it receives, as a result of the yearly Osun-Oshogbo worship festival. In this study, an initial investigation of microplastic pollution of the river water, sediments and fish species was conducted. Abundance of microplastics in the river water samples, at a maximum of 22,079 ± 134 particles/litre, represents the highest reported so far for a river water globally. FTIR analyses revealed seven polymer materials, including acrylonitrile butadiene styrene (ABS) and ethylene vinyl acetate (EVA), that have not been commonly reported for river environments. Microplastics ranged from 407 ± 244 to 1691.7 ± 443 particles in the gastro-intestinal tract (GIT) of six fish species analysed, with silver catfish (Chrysichthys nigrodigitatus) having the highest concentration. Levels in the fishes are higher than those reported for fishes in Asia and Europe, but similar to some other plastic pollution hotspots in Africa. This study recognizes the uncontrolled and indiscriminate disposal of single-use plastics as a key factor in the level of microplastic pollution of the Osun river. We emphasize the need by Nigerian government to ban certain single-use plastics, as a step towards reducing plastic pollution of Nigerian rivers, that shelter important fish species and provide water for religious and domestic purposes.