Detection and characterization of microplastics in commercial eye drops: A novel ocular exposure pathway

• This study employed three techniques, namely LDIR, Py-GCMS, and SEM, to characterize microplastics in eye drops. • Among the four brands eye drop solutions, a minimum of 2 microplastic particles and a maximum of 14 microplastic particles were detected, encompassing various types such as PE, PER, PP, ACR, and PET. • PVC is one of the main microplastic pollutants, with its content in some samples exceeding 60% of the total microplastics. Microplastics (MPs), as emerging contaminants, have infiltrated various environments and consumer products, and are widely present in human tissues and bodily fluids. Currently, there is limited research on microplastic contamination in pharmaceuticals, particularly in eye drops that directly contact the ocular surface, where the risk of microplastic exposure urgently requires evaluation. This study investigated microplastic contamination in eye drops, aiming to assess the presence of microplastics in over-the-counter eye drops used directly on the ocular surface. The study employed multiple analytical methods, including laser direct infrared spectroscopy (LDIR), pyrolysis gas chromatography-mass spectrometry (Py-GC/MS), and scanning electron microscopy (SEM), to test commercially available eye drop samples. The results revealed that microplastics were present in all tested brands of eye drops, with most particles being smaller than 100 µm and primarily composed of polymers such as polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (PP). Variations in the quantity, type, and morphology of microplastics were observed among different brands, suggesting that production processes or packaging may be sources of contamination. The study indicates that microplastic contamination in eye drops, which are formulations that directly contact the ocular surface, may pose potential risks to ocular health. Current pharmaceutical quality control standards do not yet cover such contaminants, highlighting the urgent need for attention from regulatory authorities, manufacturers, and medical professionals.