Microplastics are plastic particles smaller than 5 millimeters that arise both from the breakdown of larger plastic items and from products that intentionally contain tiny plastic beads or fibers. They are now found in oceans, rivers, lakes, soils, the atmosphere, and even in remote regions such as the Arctic and high mountains.

Research shows that microplastics are ingested by a wide range of organisms, from plankton to fish, birds, and mammals. Ingested particles can accumulate in digestive systems and tissues, sometimes impairing feeding, growth, and reproduction. Microplastics can also act as carriers for other pollutants, such as persistent organic chemicals or heavy metals, which may adhere to their surfaces and then transfer into organisms.

Humans are exposed through food, drinking water, air, and household dust. Microplastics and even smaller nanoplastics have been detected in human stool, blood, lungs, placenta, and other tissues. Laboratory studies suggest they can trigger inflammation, oxidative stress, and immune responses, although the health implications of typical environmental exposure levels remain uncertain. There is concern about effects on cardiovascular disease, metabolism, and pregnancy, but clear causal links in real-world conditions are still being established.

Research priorities include understanding how much microplastic people actually absorb, which particle sizes and shapes are most harmful, how attached chemicals contribute to toxicity, and how chronic exposure affects ecosystems and human health over decades. Scientists also emphasize prevention through reduced plastic production, better waste management, and development of safer materials that degrade more completely in the environment.