Micro- and Nanoplastics in South and Southeast Asia: Lessons Learned and Future Directions.

Micro- and nanoplastics (MNPs) are becoming a significant public health concern, with growing evidence of widespread human exposure in South and Southeast Asia through food, drinking water, air, and occupational settings. Nanoplastics, in particular, represent an under-recognized fraction with distinct exposure pathways and biological relevance. Although causal pathways are not fully established, the consistency of regional exposure patterns and emerging toxicological evidence warrant policy attention. In this region, rapid plastic production, high levels of mismanaged waste, large informal recycling sectors, and climate-exposed riverine and coastal systems create complex and overlapping exposure pathways. These conditions disproportionately affect vulnerable populations, including children, pregnant women, informal workers, and coastal communities. Key findings indicate that MNP exposure is widespread, poorly monitored, and inadequately addressed by policies that focus mainly on macroplastic waste management rather than health protection. Current regulatory frameworks rarely distinguish between microplastics and nanoplastics, even though their behavior, detection, and toxicity differ. This review identifies fragmented governance and weak integration across environmental regulation, food safety, occupational health, and public health systems as key policy gaps. Lessons from air pollution, lead, and other environmental hazards highlight the risks of delaying action. Priority policy directions include applying the precautionary principle, strengthening integrated surveillance and biomonitoring, regulating upstream plastic sources, and protecting high-risk populations. Ministries of Health should integrate MNP exposure into surveillance systems, occupational health frameworks, and maternal and child health programs.