Microplastics ubiquity in freshwater, marine and coastal environments in Malaysia: A critical review

Malaysia, as a developing country in Asia continues to be plagued with microplastics (MPs) pollution. This review presents an in-depth analysis of the MPs pollution in Malaysia within the freshwater, marine and coastal matrices. Specifically, 74 studies on MP conducted between 2014 and 2025 focusing on rivers, lakes, estuaries, mangroves, coastal environment and beaches are reviewed from the aspects of respective pollution source points and observed concentration ranges. Moreover, the interplay between these factors and their effect on the relative distinct predominant MP types is also comprehensively presented. Our analysis indicate that the Langat River exhibits the highest microplastic levels, ranging from 181 to 4,157 particles/L, primarily consisting of fragments and fibers, often less than 1 mm in size. Conversely, seawater is characterized by lower MP concentrations and sizes typically ranging from 1-5 mm. Major pollution sources include illicit waste disposal, urban runoff, and agricultural practices, raising public health concerns as ⁓97% of Malaysia's drinking water is sourced from these waterways. Recent research suggests a shift towards monitoring river basins rather than small, isolated sections as well as a bi-directional matrice (water and sediment) and seasonal variations in MP abundance analyses in order to ensure targeted pollution mitigation and support informed legislation. In the only metagenomic study, extensive microbial colonization, with over 37,613 genes present across polyethylene terephthalate and polylactic acid MPs was reported. Surface water characterization, bio-based materials integration as well as tyre-derived MPs are crucial future research directions that will foster a sustainable and circular bioeconomy in Malaysia. • The current status, emerging trends, and research gaps in microplastics studies in Malaysia were systematically reviewed. • The most frequently studied rivers in Malaysia include the Langat, Tebrau, Skudai, Semenyih, and Cherating rivers, as well as the Selangor River Basin. • Data remain scarce for several key aquatic environments, particularly estuaries, lakes, and small streams. • There is a clear need for research on the plastisphere and on chemical adsorption processes occurring on microplastics in aquatic systems. • Quantifying the contribution of land-based sources to aquatic microplastic pollution remains a research priority