Characteristics and influencing factors of microplastics entering human blood through intravenous injection

The presence of microplastics in the human body and their potential health risks have drawn widespread attention in recent years. Microplastics have been detected in human blood, though their pathways of entry remain unclear. This study employed Raman spectroscopy and energy dispersive spectroscopy to evaluate the microplastic release characteristics of intravenous medical devices, aiming to investigate the influencing factors and the risk of microplastics entering the bloodstream. The results showed that microplastics were found in three widely-used medical devices, with abundances ranging from 0.44 to 2.00 items/n. Polyethylene, polypropylene (46.2 %), fragments (96.7 %), and white (86.8 %) were the predominant characteristics. Factors such as brand, specifications, and usage scenarios influence microplastic release, leading to differences in detection rates among different medical devices (0–100 %). Repeated use significantly increases the risk of microplastic release (p < 0.05). Notably, built-in filtration membranes do not completely retain microplastics and may pose a risk of shedding fibers themselves. Using the exposure assessment model, the estimated microplastic release per person per year was 3.75 items for syringe, 6.22 items for infusion set, and 0.35 items for vein detained needle. Overall, although the amount of microplastics entering the human body through intravenous injection is significantly lower than that from dietary exposure and other pathways, the risk of direct entry into the bloodstream remains a concern. This research provides critical evidence for understanding the direct pathways and risks of microplastic exposure in human blood from plastic medical devices, offering significant scientific value for assessing exposure pathways and the safety of medical device use.