Published on: 2.12.2019
Information produced by Finnish Environment Institute
Microplastics in water

Microplastics are not a problem that exclusively affects the oceans. They are also found in Finnish lakes and rivers, where they can pose an environmental risk.
Pieces of plastic less than 5 millimetres in size are known as microplastics. These small bits of plastic make their way into rivers and lakes from many sources.
Municipal wastewaters, which contain microplastics from cosmetics and clothes made from artificial fibres, are a significant source. When wastewater is treated, most of the microplastics are bound in the resulting sludge, and while they are kept away from water bodies, they end up being disposed in soil with the sludge.
Road traffic is another significant source of microplastics: the constant wear on car tyres may create several tons of dust on a busy stretch of street annually. The microplastics contained in this dust are carried into stormwater drains and from there into lakes and rivers.
Plastic litter from the streets goes down the same drains – including cigarette butts, which contain a large share of plastic. In winter, plastics may also end up in water with snow removed from the streets and dumped into the sea. As plastic is a durable material, instead of getting decomposed it is ground into smaller and smaller particles.
Other potential sources of microplastics include the raw materials of the plastic industry and 3D printing.
Image: © Lasse Ansaharju, Vastavalo