Microplastic contamination in commercial tilapia feeds: lessons from a developing country

Abstract

Microplastic (MP) contamination in aquaculture feed presents an increasing threat to both the aquaculture industry and global public health. This study examines the occurrence, abundance, characteristics, and risk assessment of MPs in commercial tilapia (Oreochromis niloticus) feeds. MP contamination was found in all feed samples, with the highest levels observed in grower feeds (2150 ± 70.71 MPs/kg), followed by starter feeds (1650 ± 70.71 MPs/kg) and finisher feeds (1300 ± 141.42 MPs/kg). Fibers were the dominant morphotype (85%), and polymer analysis using FTIR identified polypropylene (38.74%) and polyethylene (33.61%) as the most common polymers. Additionally, 84.64% of the extracted MPs were in the 100–1500 µm size range, posing significant health risks to tilapia and potential exposure to consumers. The estimated polymer hazard index (PHI) value for the three feed categories was very high, signaling alarming health risks. The mean polymer load index (PLI) values across the feed categories ranged from 4.23 to 8.03, indicating minor contamination. The study attributes the sources of MPs to feed ingredients, packaging materials, and processing machinery. The high PHI value underscores the need for urgent action to mitigate MP pollution in tilapia farming.