Environment and Health: Influence of Microplastic and Nanoplastics on Lung Cells

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Macroscale plastic waste polluting the earth is now a well-known issue, triggering policies that aim to limit the production and use of plastic bags and bottles, and increase of recycling. However, plastics at much smaller scale, namely, microplastics (particles < 5 mm) and nanoplastics (particles < 1 um), can have insidious effects, which raise growing awareness and concern. These particles are produced from a variety of sources, such as breakdown of larger plastic debris into smaller pieces, synthetic clothing fibres, dust from tyres, and even from chewing gums and toothpastes. MNPLs are ubiquitous in the marine environment, which are now found inside living organisms, and can have diverse impact on marine ecosystems and humans through physical damage and chemical transfer of toxicants. Humans are extensively and inevitably exposed to environmental MNPLs, mainly through inhalation and ingestion.1-3 MNPLs are now ubiquitous in our daily life; for example, a recent analysis of tap water samples from around the world found that a high proportion (>80%) of drinking water is contaminated with MNPLs. MNPLs can cause oxidative stress, inflammatory lesions, increased internalization or translocation through tissues. Once internalized, MNPLs can release toxic compounds added during manufacture to enhance the polymers' performance. Additionally, MNPLs can adsorb and facilitate the transport of other environmental contaminants and pathogens into living organisms, in the way of a Trojan horse. Microplastics have recently been detected in human lungs, phlegm and bloodstream; and studies suggest that exposure to MNPLs contributes to respiratory problems in certain groups of workers.4-6 Experiments in rodents support a detrimental role of MNPLs in lung health, e.g., via changes in the epithelial cells that line the airways, increased inflammation, and airway tissue thickening (termed "fibrosis").7,8 This project will study the effects of MNPLs on airway smooth muscle (ASM) and epithelial cells that surround the airways in fibres/bundles, which are important as they help maintain the airway calibre in health and can become dysfunctional in respiratory disease that contributes to breathing difficulties. The lung microbial community also plays a major role in respiratory health and disease, which will be influenced by MNPLs and will be explored.