The impact of micro- and nanoplastics on human pulmonary health; an umbrella review

The pervasive environmental contamination of microplastics (MPs) and nanoplastics (NPs) has raised significant public health concerns, with the respiratory tract being a critical route of exposure. While a growing body of evidence suggests adverse pulmonary effects, a comprehensive synthesis of systematic reviews (SRs) is lacking. This umbrella review systematically consolidates evidence from published SRs to evaluate the impact of MP and NP exposure on human pulmonary health. Accordingly, a comprehensive literature search was conducted across multiple databases. Fifteen SRs meeting the inclusion criteria were critically appraised using the AMSTAR-2 tool and included for narrative synthesis. The evidence unequivocally links MP/NP exposure to a spectrum of respiratory pathologies. Key determinants of toxicity can include particle size, shape, and polymer chemistry. NPs penetrate deeply into alveoli, causing oxidative stress, inflammation, and translocation, while MPs act as persistent irritants in the airways. Exposure is associated with acute conditions (airway inflammation, alveolar damage) and chronic diseases, including chronic bronchitis, chronic obstructive pulmonary disease (COPD) exacerbation, and pulmonary fibrosis. These effects lead to functional impairments such as reduced gas exchange and a progressive decline in lung function. Urban residents, occupational workers, and children are identified as high-risk populations due to heightened exposure and susceptibility. This synthesis study establishes MPs and NPs as a significant and multifaceted hazard to respiratory health. Addressing the global plastic pollution crisis at its source is paramount for protecting respiratory health.