Critical perspectives on microplastics: Unresolved knowledge gaps, policy innovation, and integrated mitigation strategies

Microplastic pollution has emerged as one of the most pressing global environmental challenges, threatening ecosystem integrity, biodiversity, human health, and sustainable development. Originating from both primary sources, such as microbeads and industrial pellets, and secondary fragmentation of larger plastic debris, microplastics have become ubiquitous contaminants across marine, freshwater, terrestrial, atmospheric, and biological systems. Despite substantial advances in research, critical uncertainties remain regarding their sources, environmental transport and transformation, bioavailability, ecological fate, ecotoxicological effects, and long-term human health implications. This review critically synthesizes current scientific evidence by identifying unresolved knowledge gaps, evaluating methodological limitations, assessing policy and regulatory frameworks, and examining integrated mitigation strategies. Particular emphasis is placed on the need for standardized sampling and analytical protocols, harmonized monitoring frameworks, advanced detection technologies, and robust ecotoxicological and epidemiological studies to improve data comparability, mechanistic understanding, and risk assessment. The review further examines shortcomings in current governance, including fragmented regulations, inconsistent implementation of Extended Producer Responsibility (EPR), weak enforcement, limited lifecycle-based policies, and the absence of a legally binding international framework to address the transboundary nature of microplastic pollution. To overcome these challenges, an integrated management framework is proposed that combines scientific innovation, evidence-based policymaking, circular economy principles, sustainable material and product design, improved waste management, technological innovation, and multi-stakeholder collaboration. Bridging the science-policy interface is essential for translating scientific evidence into effective environmental management. By identifying future research priorities and policy opportunities, this review provides a comprehensive roadmap for reducing microplastic emissions, strengthening environmental governance, protecting ecosystem and human health, and advancing the United Nations Sustainable Development Goals, particularly SDGs 3, 6, 12, 14, and 15.