Microplastic Pollution In Eye Drops: Investigating Microplastic Contamination In Disposable And Multi-Use Artificial Tears

To investigate the exposure to microplastics (MP) in multi-use and disposable artificial tear (AT) products.

in vitro experiments using 5 commercial AT products (two multi-use and three disposable AT products)

AT products were used to gauge the MP levels in three scenarios: 1) initial drop and liquid remaining after opening the lid upward; 2) liquid remaining after opening the lid downward and discarding two drops; and 3) liquid remaining after opening the lid downward and discarding half of it. Raman spectroscopy was used to identify the presence, morphology, and composition of MPs, and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) was used to examine the surface traits and element signatures of MPs and AT products. The quantity and characteristics (color, shape, and polymer type) of the MPs were compared for the three scenarios.

MPs were detected in 30% of the samples, with notable differences in their concentrations across the scenarios. In the first scenario, the initial drops contained 0.44 ± 0.68 particles per 30 mL, whereas the remaining solution had 0.78 ± 0.92 particles per 30 mL. After discarding two drops in the second scenario, 0.33 ± 0.67 particles (30 mL^–1) were present in the remaining solution. No MPs were detected in any of the samples in the third scenario. Most MPs were transparent (95%) irregular fragments (55%) sized 10–20 μm (35%) and made of PE polymer types (95%). SEM images revealed fractures, scratches, ridges, and rough surfaces on the MPs and AT containers. 

MPs are found in commercially available ATs, and humans can be exposed to them; therefore, efforts are required to reduce MP contamination in ATs.