Microplastics in different nasal irrigation options.

Purpose: We aimed to assess the presence of microplastics in nasal irrigation methods commonly used in the treatment of sinusitis and rhinitis, and to evaluate human exposure.

Methods: A total of 150 samples were included in the study, consisting of nasal wash bottles containing nasal irrigation solution, seawater spray, syringes for nasal irrigation with isotonic solution. The amount of microplastics per millilitre in the samples and patient exposure during single use were assessed separately for each method and product. All samples were filtered using a stainless steel vacuum filter on filter paper with a pore size of 1.2 μm, washed at least three times with distilled water and incubated at 45 °C for 24 h to prevent mould growth. Identification and counting of microplastics was performed using a Leica Flexacam C1 camera connected to an M80 stereomicroscope. The presence of microplastics was confirmed by the hot needle method and Nile red staining.

Results: An average of 6.49 ± 13.08 microplastics/product was detected in all filtered samples. The lowest microplastic count was 0 microplastics/product in syringes and the highest was 92 microplastics/product in nasal wash bottles. Significant differences in the amount of microplastics individuals were exposed to during a single use were found between nasal wash bottles and seawater brands, while no significant differences were found between syringe brands. When nasal wash kits, seawater sprays and isotonic nasal rinses were evaluated separately, significant differences were found in the number of microplastics, the microplastics/ml ratio and the number of microplastics exposed during a single use. The highest microplastic exposure was found in nasal irrigation bottles.

Conclusion: The exposure of individuals to microplastics increases with medical support treatments, regardless of intranasal or intravenous administration. Due to the inflammation, oxidative stress and proliferation caused by microplastics, new regulations and inspections of production conditions should be implemented worldwide to reduce exposure.