Microplastics are plastic fragments under 5 millimeters. Primary sources include synthetic clothing fibers (released in laundry), tire wear, and intentionally added microbeads in cosmetics and exfoliants — the last of which are now banned in many countries.
Microplastics have been found in human blood, lungs, placentas and drinking water. Long-term health effects are still under research; the precautionary case for reducing exposure is strong.
Practical actions: choose natural fibers where possible, use a Guppyfriend or Cora Ball laundry catch, switch to bar soaps and powder detergents, and support extended producer responsibility (EPR) policies.