Plastic is one of the most remarkable materials ever created. It\u2019s cheap, lightweight and endlessly versatile. It can be shaped into anything from shopping bags to lifesaving tools in hospitals, and it\u2019s clean, safe and can be sterilised. Depending on its purpose, it can be used just once \u2013 for example, in medical settings where hygiene is critical \u2013 or kept in service for years.<\/p>\n
Perhaps surprisingly, plastic can even have environmental benefits thanks to its light weight, which reduces fuel use in transport<\/a>. But we have become so dependent on plastic that global production reached around 414 million tonnes in 2023<\/a> \u2013 a figure that continues to rise every year.<\/p>\n Plastic is part of countless everyday objects<\/a>. Take a toothbrush: the bristles are usually nylon, while the handle is often made from lightweight polyethylene or polypropylene. A manual toothbrush might have a volume of 8.5-19 cm\u00b3. Now imagine that over time, it breaks down into microplastics \u2013 fragments smaller than five millimetres \u2013 or even nanoplastics, which are a thousand times smaller.<\/p>\n If microplastics<\/a> can be as small as 1 micrometre (about the size of a bacterium) \u2013 or even 0.1 micrometres (roughly the size of the SARS-CoV-2 virus) \u2013 a single toothbrush could theoretically break into 8.5-19 trillion microplastics. And these particles are small enough to be inhaled or ingested.<\/p>\n<\/p>\n Plastics don\u2019t simply \u201cvanish\u201d in the environment: they fragment. Sunlight, especially ultraviolet-B (UV-B) radiation, makes plastic brittle<\/a>; physical stress \u2013 waves, wind, abrasion \u2013 breaks it into ever-smaller pieces. Even the state of the stratospheric ozone layer, which controls how much UV-B reaches Earth, can influence how quickly plastics degrade<\/a>. Some bacteria and fungi can also contribute to breaking down certain plastics<\/a>, but this is slow and often incomplete<\/a>.<\/p>\n The result? Most plastic waste ends up as a soup of micro- and nanoplastics drifting through our environment.<\/p>\n While larger plastic debris can cause obvious harm, such as entangling wildlife or being swallowed by seabirds, microplastics are a quieter but potentially more insidious problem.<\/p>\n Plastic everywhere<\/p>\n Microplastics have now been found inside 1,300 species of invertebrates<\/a> and are present at every level of the food chain. These particles are oil-like (hydrophobic), which helps them cross biological membranes and enter the cells of living organisms \u2013 unlike water-loving (hydrophilic) particles such as grains of sand, which follow a different biological path.<\/p>\n Their size matters, too. Smaller particles can travel more easily within the body, reaching organs far from where they first entered. Exposure can occur through swimming in polluted water or via food and drink \u2013 either because the food itself contains plastic particles (such as seafood from contaminated waters) or because it\u2019s been contaminated during packaging or industrial processing.<\/p>\n Micro- and nanoplastics can also be inhaled in airborne dust, particularly in certain workplaces, such as textile manufacturing or sandblasting with plastic-based materials. In everyday life, we can breathe in synthetic fibres shed from our clothes or tiny particles released from tyre wear.<\/p>\n Once inside, microplastics have been found to move \u2013 a process called translocation<\/a> \u2013 within animals, a phenomenon that has not been found in humans yet.<\/p>\n<\/p>\n Evidence now shows<\/a> that micro- and nanoplastics are present in human liver, kidney, lung, spleen, blood, heart and brain. In one study<\/a>, nanoplastic shards of polyethylene were detected in human brains, at higher concentrations than in the liver and kidney. They have been found in the fat plaque in arteria which is related to cardiovascular problems<\/a>. They have also been found in the placenta and breast milk<\/a>, suggesting that these particles can be transferred across generations. <\/p>\n Given how common plastics are in food and drink, their presence in the human body isn\u2019t surprising \u2013 but detecting them is technically challenging<\/a>. Samples are often collected in hospital environments where plastics are everywhere, creating a high risk of contamination.<\/p>\n Are they harmful?<\/p>\n Researchers are beginning to investigate<\/a> associations between plastic particles and human health conditions including cardiovascular disease<\/a>, pulmonary fibrosis<\/a> \u2013 a lung disease in which tissue becomes scarred and stiff, making it harder to breathe \u2013 as well as liver and bowel disease<\/a>.<\/p>\n Read more: But the science is still young. Large-scale epidemiological studies, which could take years to complete, will be needed<\/a> to determine whether plastics directly cause these illnesses.<\/p>\n
\n Plastics threaten ecosystems and human health, but evidence-based solutions are under political fire<\/a><\/p>\n