Pigment microparticles and microplastics found in human thrombi based on Raman spectral evidence

Introduction: Environmental microparticle is becoming a global pollutant and the entire population is increasingly exposed to the microparticles from artificial materials. The accumulation of microparticles including microplastics and its subsequent effects need to be investigated timely to keep sustainable development of human society.Objectives: This study aimed to explore the accumulation of environmental particles in thrombus, the pathological structure in the blood circulation system.Methods: Patients receiving cardiovascular surgical operations were screened and twenty-six thrombi were collected, digested and filtered. Non-soluble microparticles were enriched on the filter membrane and then were analyzed and identified with Raman Spectrometer. The associations of particle status (presence or absence) or particle number in the thrombus and clinical indicators were examined. One strict quality control-particle detection system was designed to eliminate environmental contaminations.Results: Among twenty-six thrombi, sixteen contained eighty-seven identified particles ranging from 2.1 to 26.0 lm in size. The number of microparticles in each thrombus ranged from one to fifteen with the median reaching five. All the particles found in thrombi were irregularly block-shaped. Totally, twenty-one phthalocyanine particles, one Hostasol-Green particle, and one low-density polyethylene microplas-tic, which were from synthetic materials, were identified in thrombi. The rest microparticles included iron compounds and metallic oxides. After the adjustment for potential confounders, a significantly pos-itive association between microparticle number and blood platelet levels was detected (P < 0.01).Conclusion: This study provides the first photograph and Raman spectrum evidence of microparticles in thrombi. A large number of non-soluble particles including synthetic material microparticles could accumulate in arteries, suggesting that the risk of microparticle exposure was under-estimated and the reevaluation of its health effects is urgently needed. There will be a series of reports on assessing the health effects of microparticle exposure in humans in the future and this research provided clues for the subsequent research.& COPY; 2022 The Authors. Published by Elsevier B.V. on behalf of Cairo University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study aimed to investigate the accumulation of environmental particles in thrombus and their effects on the blood circulation system. Non-soluble microparticles, including synthetic material microparticles and iron compounds, were found in a large number in thrombi. The study also revealed a significant positive correlation between microparticle number and blood platelet levels. These findings suggest that the risk of microparticle exposure has been underestimated and further research is urgently needed to assess its health effects.