Toxicological effects of polypropylene nanoparticles similar in size to nanoplastics in plastic-bottled injections on mice and zebrafish

Nanoplastics may threaten human health, most current toxicological studies focus on polystyrene, but no study on polypropylene (PP) in plastic bottled injections for medical care. Based on the amount of nanoplastic from PP-bottled injections introduced by intravenous infusion average daily in infants (31.5 ng) and adolescents (157.5 ng), we explored the toxicological effects of PP-NPs on the organ development of zebrafish. We also investigated the toxicological effects in mice of PP-NPs at doses based on the number that people introduced from injections per year in 2024 (3.5-35 μg). The PP-NPs similar in size to nanoplastics present in PP-bottled injections were administered intravenously to zebrafish larvae and mice. We showed that PP-NPs could be transferred from the zebrafish heart to the liver or gut, resulting in a mortality rate of up to 23%; their deposition also occurred in the mice's liver, spleen, and lungs, with a tendency to inhibit growth. In addition, PP-NPs (25 ng) can induce cardiovascular toxicity in zebrafish and cause liver inflammation, steatosis, and lipid deposition, resulting in the disappearance of some nucleoli and mitochondrial damage; cumulative injection of 927.5 μg could induce a significant increase in the number of spleen tingible body macrophages and lung granulomatous inflammation in mice, promoting hepatocyte necrosis. Finally, NPs introduced by blood vessels can cause both digestive organ damage, similar to that originally induced by the oral route, and respiratory organ damage, which can be induced by the inhaled route. Overall, this is the first systematic evaluation of the toxicological effects of PP-NPs on human animal models, which is helpful for indirectly accessing their potential risks to the development of neonatal organs and adult health possibly.