What are "microplastics"?
A new term has been introduced and used in the field of marine debris--microplastics. Typically, when used it encompasses a range of small pieces of plastic marine debris. For its purposes, the NOAA Marine Debris Program defines microplastics as plastic debris pieces in the size range of 0.3-5mm (i.e., the thickness of two human hairs side by side to the size of a grain of rice).
There are two categories of microplastics:
1) Primary microplastics: Intentionally produced for direct use, or as pre-cursors to other products. Examples of sources include point-of-origin or manufacturing losses (e.g., pre-production plastic pellets) and plastic spherules in personal care products like facial scrubs (typically made of polyethylene).
2) Secondary microplastics: Formed from the breakdown of larger plastic material. Examples of sources include point-of-use losses, any polymer fragment formed by weathering, and breakdown of “bio-degradable” polymers.
Credit: http://marinedebris.noaa.gov/info/plastic.html#2
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