Where do microplastics come from?

Microplastic pollution is not limited to bottles and straws. Many important sources are created gradually as products wear, shed, and weather.

Left: an artificial turf pitch filled with black rubber crumb. Right: a hand holding rubber crumb granules found in soil beside a stream — The same material in two places: rubber crumb infill on an artificial pitch (a), and crumb carried off that pitch by rain and found in the ground beside a nearby stream (b). Sports surfaces and other outdoor plastics shed where they are used, then travel. Soleincitta, Wikimedia Commons · CC BY-SA 4.0

Sources hidden in everyday use

Well established

Composite photograph of a researcher at a microscope and a researcher collecting water from a dock — Laboratory and field work connect tire-wear pathways with effects testing in estuarine fish. NOAA NCCOS, Tire-wear particle research · U.S. government work

Tire wear: Friction between tires and roads produces particles that can move with road dust, runoff, and air.
Synthetic textiles: Polyester, nylon, and other synthetic materials can shed fibres during manufacturing, wear, washing, and drying.
Paint and coatings: Building paint, road markings, marine coatings, and other painted surfaces release particles as they weather and abrade.
Artificial turf: Plastic grass blades and infill can fragment and migrate beyond playing surfaces.
Packaging and litter: Sunlight, heat, wind, waves, and friction make larger plastic brittle and break it into smaller pieces.
Industrial pellets: Small resin pellets used to manufacture plastic products can be lost during production and transport.
Personal-care and industrial products: Some products use intentionally manufactured small plastic particles, although restrictions differ by country and product.

Source: U.S. EPA microplastics research

A polyester garment’s possible path

Emerging

Fibres can be released while a garment is produced, worn, washed, or dried. Some are captured by filters or wastewater treatment; others may remain in sludge, enter rivers, settle into soil, or travel through air.

There is no single path for every fibre. Product construction, washing conditions, treatment systems, and local waste practices all affect where it goes.

Rainwater flowing along a curb and into a storm drain — Rain carries material from streets into storm-drain systems—the first leg of an important California transport pathway. U.S. Geological Survey, USGS storm-drain photograph · Public domain

1 · Make and wear: Cutting, finishing, friction, and ordinary wear release fibres.
2 · Wash and dry: Water and mechanical action carry shed fibres into wastewater; dryers can also move fibres into air and lint.
3 · Capture or pass through: Filters and treatment retain some material. Performance changes with particle size and the local system.
4 · Water, sludge, soil, or air: Uncaptured fibres and retained sludge follow different local pathways rather than one universal route.