When most people think of plastic pollution in the sea, they tend to picture bottles washing up on beaches, say, or the vast garbage patch in the Pacific.

What few may realize is that waste water from washing machines is an important source of plastic pollution in oceans, according to a recent article in Environmental Science and Technology.

Over the last decade, scientists have become increasingly alarmed about a type of pollution that cannot be seen. Micrometer-size fragments of plastics like acrylic, polyethylene, polypropylene, polyamide and polyester have contaminated the surface waters of the northeast Atlantic as well as shoreline habitats in Britain, Singapore and India, the researchers write.