Microplastics are tiny plastic particles, typically smaller than 5 millimeters, that originate from the breakdown of larger plastic items or are manufactured at small sizes, such as microbeads and fibers. They are now found in oceans, rivers, lakes, soil, air, food, and drinking water, making them a pervasive environmental contaminant.

Research shows that microplastics come from sources like tire wear, synthetic clothing, packaging, personal care products, and degraded fishing gear. Wastewater treatment plants remove some particles but not all, allowing microplastics to pass into rivers and seas. Wind and atmospheric transport also spread them, leading to deposition even in remote regions such as the Arctic and high mountains.

In aquatic ecosystems, microplastics are ingested by organisms ranging from plankton to fish and marine mammals. Laboratory and field studies indicate potential impacts including reduced feeding, energy loss, impaired growth and reproduction, and physical damage to tissues. Microplastics can also carry chemical additives and pollutants that may transfer to organisms.

Humans are exposed by inhaling airborne particles and consuming contaminated food and water. Recent studies have detected microplastics in human blood, lungs, placenta, and stool. While the health implications are not yet fully understood, concerns include inflammation, oxidative stress, and interference with cellular processes, especially for the smallest particles, known as nanoplastics.

Ongoing research focuses on better measurement methods, understanding exposure pathways, clarifying health risks, and evaluating mitigation strategies, such as reducing plastic use, improving waste management, developing alternative materials, and capturing microplastics at key sources like washing machines and wastewater plants.