Part 1: Microplastics and Nanoplastics in Asian Seafood Supply Chains: Occurrence, Co-Contaminants, Synergistic Risks, and Plastisphere Interactions

Microplastics (MPs, <5 mm) and nanoplastics (NPs, <1 μm) are pervasive in Asian marine environments, particularly in high-production areas such as the South China Sea, Johor Straits, and Southeast Asian aquaculture zones. Driven by plastic waste, intensive farming, and coastal dynamics, these particles enter seafood supply chains through direct ingestion and act as “Trojan horses” for co-contaminants (heavy metals, PFAS, antibiotics, pesticides) while serving as scaffolds for microbial biofilms known as the plastisphere. This review synthesizes recent data (2020–2026) on MP/NP occurrence in commercially relevant seafood (bivalves, crustaceans, fish), co-contaminant interactions, plastisphere-mediated pathogen enrichment, and synergistic risks to food safety and human health. New experimental observations demonstrate that microplastics increase bacterial turbidity in culture (consistent with biofilm formation) and that natural polysaccharides (e.g., okra and marshmallow root extracts) induce visible flocculation and turbidity reduction — supporting a dual-mechanism mitigation strategy (physical aggregation + antimicrobial activity). A Z-model perspective further explains how aggregation reduces accessible surface area, limiting microbial colonization. Premium restaurant chains and seafood suppliers can leverage proactive multi-contaminant testing and field-deployable tools (e.g., the EcoExposure smartphone platform) to strengthen supplier audits, ESG reporting, MSC/ASC compliance, and brand protection. This Part 1 paper provides the scientific foundation; a companion Part 2 details practical supply-chain screening protocols and mitigation strategies for Asian restaurant operations and aquaculture.