Size-dependent translocation of polystyrene nanoplastics across biological barriers in mammals
Hongjie Zhang, Sicheng Li, X Z Wang, Ke-Da Zhang, Hai-Tao Fang, Xiaowei Wu, Ziyun Huang, Wei Jiang, Liuyan Yang, Qiao-Guo Tan, Bingcai Pan, Rong Ji, Ping Wang, Baoshan Xing, Ai‐Jun Miao
Abstract
Nanoplastics (NPs) pose health concerns worldwide. However, robust quantitative data on their absorption, distribution, and excretion in mammals remain scarce. Here, we provide a comprehensive assessment of polystyrene (PS) NP biodistribution and elimination in rats using 14C-radiolabeling, the most accurate and quantitative method available. Pregnant rats were exposed to 14C-labeled 20 nm or 100 nm PS NPs (PS20 or PS100) via oral gavage, intratracheal aerosolization, or intravenous injection, and tissue distribution and excretion were determined by radioactivity measurements. We found that PS NPs were exclusively excreted through faeces, irrespective of the exposure routes, without urinary elimination. Both PS20 and PS100 crossed multiple biological barriers, yet only PS20 reached the brain. Maternal transfer of PS20 occurred through both placenta and milk, while PS100 transferred solely via milk. A physiologically based toxicokinetic model further simulated accumulation kinetics across tissues. This study establishes the most comprehensive and reliable quantitative profile of PS NP biodistribution in mammals to date, revealing distinct size-dependent translocation patterns that provide a robust foundation for evaluating their health impacts. Previous studies on biodistribution of microplastics showed discrepancies. This study provides quantitative data to date on how nanoplastics distribute and eliminate from the body using carbon-14-radiolabelled particles in rats.