Microplastic Occurrence in Ethnic Fermented Fish Products of Northeast India

Microplastics (MPs) have emerged as a growing environmental and food safety concern, with their presence widely reported in aquatic organisms and seafood. However, their occurrence in traditionally processed and fermented fish products remains unexplored. This study provides the first evidence of MP contamination in ethnic fermented fish products of Northeast India, namely Ngari, Hentak, and Shidal. MPs were analyzed for abundance, size distribution, morphology, color, and polymer composition using microscopic examination and Laser Raman Spectroscopy. The average MP abundance was 16.50 ± 5.18 MPs/g in Ngari, 15.73 ± 4.83 MPs/g in Shidal, and 20.50 ± 3.00 MPs/g in Hentak. Fibers and fragments were the dominant morphotypes across all products, with transparent and black particles occurring most frequently. Polymer characterization revealed polyethylene (PE) and polypropylene (PP) as the predominant polymers, followed by polyamide (PA), polyvinyl chloride (PVC), and polystyrene (PS). Size distribution analysis showed that MPs in the 101–300 µm range were most abundant in Ngari and Shidal, whereas smaller MPs (<50 µm) predominated in Hentak. The use of whole fish, including the gastrointestinal tract and gills, primary sites for MP accumulation, along with non-standardized fermentation practices and atmospheric deposition during retail, likely contributes to contamination. These findings highlight an overlooked route of human exposure to MPs through traditional fermented foods and underscore the need for improved processing practices and mitigation strategies to safeguard food safety and sustainability.