Microplastic-associated toxicants in the Nile River: a scoping review of bioaccumulation and health risks.

Abstract

Microplastics (MPs) are known to carry toxic compounds in aquatic ecosystems, but information about the Nile River remains scattered. This review consolidates the current knowledge of MPs and related toxic substances in the Nile River, with a focus on bioaccumulation, transfer through the food chain, and dangers to aquatic life and human consumers. A systematic search of five databases from 2010 to 2026 identified 50 relevant studies. MPs, mainly polyethylene, polypropylene, and polystyrene fibres, were found in Nile water (2.24 to 3.76 particles/L), sediments (up to 520 particles/kg), and organisms, with more than 75% of the fish sampled from the Nile River in Cairo containing MPs. Seasonal variations resulted in higher concentrations during summer. Experiments have demonstrated the uptake of MPs and their role in transporting heavy metals, persistent organic pollutants (POPs), antibiotics, and plastic additives, increasing ecotoxicological risks. Aquatic organisms exhibit toxic effects such as oxidative stress, immune suppression, slowed growth, and reproductive problems. Although data on human health are limited, MPs and their toxic cargo have been linked worldwide to tissue buildup, inflammation, and gene damage, raising concerns for people relying on the Nile River. Despite these findings, knowledge gaps remain, especially regarding trophic transfer, biomagnification, and some health outcomes in Nile populations. This review emphasizes the need for standardized monitoring, better waste management, and targeted cleanup efforts. To our knowledge, this is the first review to specifically focus on MP-related toxicants in the Nile River, paving the way for future research in ecology and public health.