Microplastic pollution in eggs impairs chick development by disrupting yolk sac function and intestinal homeostasis

This study quantitatively assessed microplastic contamination in commercial chicken eggs and hen ovarian follicles. Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC/MS) and Laser Direct Infrared Analysis (LDIR) analyses revealed universal microplastic contamination. The dominant polymers-polypropylene, polyethylene, and polystyrene-reached concentrations of up to 227 μg/g, averaging 17.0 μg/g per egg. Crucially, maternal transfer was confirmed, with polystyrene and polyethylene detected in all ovarian follicles (6/6) at mean concentrations of 8.1 and 61.0 μg/g, respectively. To evaluate toxicity, polystyrene nanoplastics were injected into yolk sacs at 0.2, 1.0, and 5.0 mg/egg, a range where the medium dose modeled detected levels while low and high doses established dose-response relationships. Exposure caused dose-dependent growth retardation (14-day body weight: 75.4 g vs. 91.6 g in controls) and intestinal villus atrophy (556 μm vs. 787 μm). Mechanistically, transcriptomics identified disrupted autophagic flux and epithelial junctions as key toxicity pathways. This study emphasizes the potential health risks of dietary microplastic exposure.