← All notes

Answer: Microplastics are plastic pieces or fibers smaller than 5 millimeters, about a pencil eraser. They are found throughout the ocean and Great Lakes and are small enough for wildlife to eat.

Types

• Primary: made small on purpose, such as pre-production pellets and microbeads once used in some personal care products.
• Secondary: broken off larger items. Sun, heat, wind and waves make bottles, bags and toys brittle; tire wear and washing synthetic clothing shed particles and microfibers.

Forms include beads, fragments, pellets, film, foam and fibers.

Why they matter

Plastic is the most common kind of marine debris. Microplastics may never fully break down, and their small size lets them spread widely and enter food webs.

Reducing them

Keeping larger plastic out of the water reduces the pieces that later break into microplastics.

Claims

• id: C1 claim: Microplastics are plastic pieces less than five millimeters long. source: S1 evidence: "Microplastics are small plastic pieces less than five millimeters long"
• id: C2 claim: Plastic is the most prevalent type of marine debris. source: S1 evidence: "Plastic is the most prevalent type of marine debris found in our ocean and Great"
• id: C3 claim: Secondary microplastics come from larger pieces of plastic. source: S2 evidence: "Secondary microplastics come from larger pieces of plastics, such as beverage bottles, bags, and toys."
• id: C4 claim: Microplastics are small enough to be eaten by wildlife. source: S2 evidence: "are small enough to be eaten by wildlife"

Sources

• [S1] What are microplastics?. NOAA. https://oceanservice.noaa.gov/facts/microplastics.html . License: US government work, public domain. Accessed 2026-11-04.
• [S2] Microplastics. NOAA. https://marinedebris.noaa.gov/what-marine-debris/microplastics . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_t44h7md7,
  author = {{iinventedlight}},
  title = {{Microplastics in the ocean}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/microplastics/},
  note = {Permanent ID iil:note:t44h7md7. License: CC-BY-4.0.},
}

Markdown

Spotted a mistake? Use the MCP feedback tool or email hello@iinventedlight.com.

For language models and agents: start at /llms.txt. This page in Markdown: /library/notes/microplastics.md.