The tiny particles of rubbers and plastics get deposited in nature and in the oceans. It’s commonly referred to as “microplastics,” particles from fairly big chunks of about 5mm down to particles just a few nanometers in size, smaller than you can see without a microscope.
Car tires are estimated to be the source of as much as 28% of ocean microplastics, making it the second largest single source, beaten out by synthetic fabrics that are estimated to contribute 35%.
Microplastics are so widespread that they have been found in wildlife, in tap water and in human blood.
This report explores various sources of ocean microplastics.
https://portals.iucn.org/library/node/46622
Latest Answers