Measurement of microplastic release after use of polypropylene nasal irrigation bottles.

Objectives Microplastics from plastic materials can affect human health. This study aimed to assess their presence in nasal irrigation fluids obtained from reused bottles based on usage duration. Methods Readily available nasal irrigation bottles made of polypropylene were purchased. Unused irrigation bottles served as controls. Bottles mimicking 1-, 3-, and 6-month reuse were prepared as test samples. Nasal irrigation fluid samples (n=12) were collected from each set of irrigation bottles: three from new control bottles and nine from bottles mimicking 1-, 3-, and 6-month reuse. Raman spectroscopy was employed to detect microplastics in the nasal irrigation samples; the results were compared according to the bottle use duration. Results An average of 33.00±20.42 (ea/300 mL) microplastic particles was detected in the nasal irrigation fluid from the control bottles relative to an average of 68.66±30.07, 261.66±20.59, and 204.33±52.16 (ea/300 mL) from bottles used for 1, 3, and 6 months, respectively. The majority of the detected microplastics were 10-100 μm in size and fragmentshaped in form. The predominant microplastic was polypropylene, indicating direct release from irrigation bottles. Conclusion We found microplastics in nasal irrigation fluids, likely originating from the repeated use of nasal irrigation bottles. The quantity of microplastics was notably elevated in the samples obtained from bottles simulating 3 months of use compared to those in the control samples. Thus, we propose developing guidelines regulating the duration of nasal irrigation bottle usage to mitigate microplastic infiltration into the body through the sinonasal cavity.