Microplastic pollution in freshwater systems in Southeast Asia: contamination levels, sources, and ecological impacts.

Plastics are synthetic polymers known for their outstanding durability and versatility, and have replaced traditional materials in many applications. Unfortunately, their unique traits ensure that they pose a major threat to the environment. While literature on freshwater microplastic contamination has grown over the recent years, research undertaken in rapidly developing countries, where plastic production and use are increasing dramatically, has lagged behind that in other parts of the world. In the South East Asia (SEA) region, basic information on levels of contamination is very limited and, as a consequence, the risk to human and ecological health remains hard to assess. This review synthesises what is currently known about microplastic contamination of freshwater ecosystems in SEA, with a particular focus on Malaysia. The review 1) summarises published studies that have assessed levels of contamination in freshwater systems in SEA, 2) discusses key sources and transport pathways of microplastic in freshwaters, 3) outlines what is known of the impacts of microplastic on freshwater organisms, and 4) identifies key knowledge gaps related to our understanding of the transport, fate and effects of microplastic.