Modes of harm
Researchers have several theories about how plastic specks might be harmful. If they’re small enough to enter cells or tissues, they might irritate just by being a foreign presence — as with the long, thin fibres of asbestos, which can inflame lung tissue and lead to cancer. There’s a potential parallel with air pollution: sooty specks from power plants, vehicle exhausts and forest fires are known to deposit in the airways and lungs, and high concentrations can damage respiratory systems.
Marine life
Fibres seem to be a particular problem. Compared with spheres, fibres take longer to pass through zooplankton, Lindeque says. In 2017, Australian researchers reported that zooplankton exposed to microplastic fibres produced half the usual number of larvae and that the resulting adults were smaller. The fibres were not ingested, but the researchers saw that they interfered with swimming, and identified deformations in the organisms’ bodies. Another study in 2019 found that adult Pacific mole crabs (Emerita analoga) exposed to fibres lived shorter lives.
Although microplastics don’t seem like a big problem right this instant, it will have a huge impact on different species including us. This may mean that the individuals capable of surviving extremes will be alive for a longer period of time, for example some people may have bodies that are able to store large amounts of microplastics.