Microparticles introduced by the processing of traditional Chinese medicine Hirudo nipponica Whitman might pose threat to patients.

Hirudo nipponica Whitman (HNW) is a traditional Chinese medicine (TCM) processed from leeches, commonly used for treating blood stasis syndrome, particularly in promoting blood circulation and alleviating blood stasis. This study aimed to examine microparticles (MPs) contamination of leeches and whether the production of MPs was related to processing. The results showed that the abundance of MPs in the whole, sectioned and powdery of HNW was 12.39, 13.93, 35.11 items/g, respectively. Fiber-like particles accounted for 90 % total. Transparent particles were the most abundant, followed by blue and black. Particles <1 mm were the most frequent. Notebly, 100 % cotton was the most detected material in the HNW, while rayon, cellulose and polyester accounted for 46 % of the total. The abundance of particles in powdery HNW increased significantly, with a higher percentage of <1 mm, similar type and colour to whole and sectioned HNW. It suggests that the large MPs may have been cut into smaller MPs during processing and bring more risk of MPs. It alerts us to the fact that pharmaceuticals and even commonly touched food products may pose a greater risk of MPs due to processing.