A study on microplastics occurrence and dietary intake from staple foods and tap water in western Iran

This study investigates the occurrence, characteristics, and estimation of consumer exposure to microplastics (MPs) in a collection of staple foods and tap water in the city of Kermanshah (in western Iran). For this purpose, samples of rice, bread, milk, yogurt, meat, edible oil, and tap water were collected. MPs in each sample were counted using a stereo microscope and classified by shape, size, color, and type (with limitation). The highest average contamination was observed in unrinsed rice (198.00 particles/kg) and the lowest in tap water (4.10 particles/L). The most abundant MPs shape was fiber (76.09%), and blue-colored MPs were also more frequent (69.27%). 31.34% of the particles were in the size range of 500 to 1000 μm, and 30.86% had a size < 500 μm. The identified polymers included (probably) polypropylene (PP), polyethylene (PE: High/Low-Density), and polystyrene (PS). The Cumulative Estimated Annual Intake (CEAI) was 3.8 × 105 particles/kg of bw for children and 8.7 × 104 particles/kg of bw for adults. The Cumulative Estimated Daily Intake (CEDI) was 1047 particles/kg of bw for children and 240 particles/ kg of bw for adults. The results of this research indicate the widespread presence of MPs in the staple food basket of Kermanshah residents, which may raise health concerns (especially for more vulnerable age groups), thus monitoring measures and actions to prevent further contamination are essential. This study has several methodological limitations, including visual MP identification (error risk), no recovery experiments, and polymer analysis only on larger particles. Future work should address these issues.