> <i>In recent years, studies have revealed the kind of threat microplastics pose to marine creatures. This has included weakening the adhesive abilities of muscles, impairing the cognitive ability of hermit crabs and causing aneurysms and reproductive changes in fish. They've turned up in the guts of sea turtles all over the world, and been discovered in seal poo as evidence of them traveling up the food chain. Research has also shown they can alter the shape of human lung cells</i><p>> <i>researchers at Daegu Gyeongbuk Institute of Science and Technology orally administered polystyrene microplastics two micrometers in size or smaller to mice over the course of seven days[: ...] in the brain ... the particles built up in the microglial cells, ... and this had a significant impact on their ability to proliferate. This was because the microglial cells saw the plastic particles as threat, causing changes in their morphology and ultimately leading to apoptosis (programmed cell death).</i><p>> <i>The study shows that microplastics, especially microplastics with the size of 2 micrometers or less, start to be deposited in the brain even after short-term ingestion within seven days, resulting in apoptosis, and alterations in immune responses, and inflammatory responses</i><p>This abridgement is just for comfort: the divulgative article is quite short.<p>Original research article: <i>Microglial phagocytosis of polystyrene microplastics results in immune alteration and apoptosis in vitro and in vivo</i>, <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969721058952?via%3Dihub" rel="nofollow">https://www.sciencedirect.com/science/article/abs/pii/S00489...</a><p>An infographic is present ( <a href="https://ars.els-cdn.com/content/image/1-s2.0-S0048969721058952-ga1_lrg.jpg" rel="nofollow">https://ars.els-cdn.com/content/image/1-s2.0-S00489697210589...</a> ), but the main information that 10 micrometers particles should not pass the barrier, while 2 micrometers particles may.