The Impact of Microplastics on Allergy: Current Status and Future Research Directions

BACKGROUND: Microplastics (MPs) constitute an emerging category of environmental pollutants that have attracted considerable scientific scrutiny due to their widespread global distribution and documented health hazards. Importantly, these particles pose a threat to human health by disrupting epithelial barriers, which in turn heightens susceptibility to allergic sensitization and exacerbates pre-existing allergic conditions. SUMMARY: This review consolidates contemporary evidence regarding the involvement of MPs in allergic diseases, focusing on their principal sources, such as environmental degradation and consumer products, as well as their exposure pathways, including inhalation, ingestion, and dermal contact. It elucidates the mechanisms by which MPs provoke immune disturbances - specifically Th2 polarization, alarmin release, and oxidative stress - that collectively contribute to allergic inflammation. Furthermore, the analysis underscores the epidemiological correlation between MPs and the increased incidence and severity of asthma, allergic rhinitis, and atopic dermatitis, in alignment with the epithelial barrier hypothesis. KEY MESSAGES: MPs compromise epithelial barriers and promote type 2 inflammation. There is an urgent need to elucidate dose-dependent immunotoxicological mechanisms. Evidence-based policies are required to mitigate exposure and allergy burden.