Microplastics in the air are infiltrating human lungs, triggering oxidative stress, inflammation and cellular damage that may contribute to a range of serious respiratory diseases, a comprehensive new scientific review has warned.
The paper, published in Food Bioscience, synthesises evidence from dozens of studies examining the impact of inhaled microplastics on lung health. It concludes that these pervasive environmental pollutants are not passive passengers in the respiratory tract but active agents of harm.
The review highlights multiple pathways through which microplastics may drive disease. In asthma, the particles have been shown to disrupt the epithelial barrier – the lung’s first line of defence – by reducing key proteins that hold cells together. They also promote inflammatory cell infiltration, mucus overproduction and airway remodelling, all hallmarks of severe asthma.
In chronic obstructive pulmonary disease, microplastic exposure was associated with impaired lung function, alveolar wall thickening, and collagen deposition. Gene analysis revealed disruptions in pathways governing mitochondrial health and endoplasmic reticulum stress, both implicated in COPD progression.
The evidence for pulmonary fibrosis is particularly concerning. Animal studies show that inhaled microplastics can trigger fibroblast hyperactivation and excessive collagen deposition – the scarring process that stiffens lung tissue and destroys its ability to exchange oxygen. One study found that microplastics accumulated in lung tissue, promoting fibrosis even at relatively low doses.
The review also points to a potential link between microplastics and lung cancer. Human tumour tissues have been found to contain significantly higher levels of microplastics than healthy tissue, with lung cancer samples showing the greatest burden and polymer diversity. Laboratory studies suggest microplastics may promote cancer cell migration and metastasis, even at very low concentrations.
The lungs are particularly vulnerable to microplastic injury due to their anatomy. Particles smaller than 2.5 micrometres can bypass the upper airway defences and settle deep in the alveoli, where gas exchange occurs. Unlike the gut, which can expel particles, the lungs lack efficient clearance mechanisms for nanosized plastics, allowing them to persist and accumulate.
The review also highlights how microplastics interact with lung surfactant – the delicate lipid-protein film that reduces surface tension and prevents alveolar collapse. This interaction impairs surfactant function, potentially compounding respiratory damage.
The research was led by Dr Keshav Raj Paudel from the University of Technology Sydney, who said: ‘Earlier research on microplastics focused mainly on oceans and human exposure through eating seafood, however growing evidence suggests that inhalation may be an equally, if not more significant route.
‘The lungs are particularly vulnerable to microplastic damage due to their large surface area and limited ability to clear particles, particularly smaller ones that travel deep into the lungs. Lung cancer tumours have been found to contain more microplastics than healthy tissue.
‘Different plastics also have varying degrees of toxicity. For example, polystyrene microplastics can stick to the lungs’ protective coating, disrupt air sac function and trigger chemical reactions that may damage lung tissue.’
The full research can be read here.
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