---
source: https://iinventedlight.com/library/notes/microplastics.md
title: "Microplastics in the ocean"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NOAA, What are microplastics?, US government work, public domain; NOAA, Microplastics, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "ocean: pollution"
tags: ['ocean', 'microplastics', 'plastic', 'pollution']
sources:
  - id: S1
    title: "What are microplastics?"
    publisher: NOAA
    url: https://oceanservice.noaa.gov/facts/microplastics.html
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "Microplastics"
    publisher: NOAA
    url: https://marinedebris.noaa.gov/what-marine-debris/microplastics
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# Microplastics in the ocean

**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).