Swirls of trashed plastic litter the seven seas. But it's not the enormous plastic patches that pose the biggest pollution problem. Instead it's bits of plastic less than one millimeter in size.
Such microplastic litters shorelines like grains of sand, floats in the open ocean and even sinks down to the deep sea. And sampling the microplastic on shorelines reveals that most of it comes from sewage. That’s according to an analysis in the journal Environmental Science and Technology. [Mark Anthony Browne et al., "Accumulation of Microplastic on Shorelines Woldwide: Sources and Sinks"]
But how did the microplastic get in the sewage in the first place? Most of the particles were plastics commonly used in clothes—polyester and acrylic. Similar levels of such particles were found in the discharge from nearby sewage treatment plants. And that means most of the microplastics were coming from our washing machines.
Fleece is the worst shedder. But various plastic-based garments can lose more than 1,900 fibers per wash. The solution may be to add better filters, either to washing machines or to the sewage treatment plants that deal with all the wash water.
Otherwise, all that plastic ends up stored in cells of sea life. And that's not very clean.
[The above text is a transcript of this podcast.]