What are microplastics and nanoplastics?

There is growing interest in the threats that microplastics and nanoplastics pose on the health of humans and the environment. In this article we answer the questions: what are microplastics and nanoplastics? where do they come from? and more.

What are microplastics and nanoplastics?

Microplastics (MPs) and nanoplastics (NPs) are tiny pieces of plastics measuring less than 5 millimetres and between 1 and 1000 nanometres in diameter, respectively (1).

Where do they come from?

MPs and NPs can originate from the breakdown of larger pieces of plastic articles that end up in the environment or can be added to manufactured products such as personal care products and clothing (1, 2).

Where can they be found?

Pretty much everywhere: bodies of water (such as oceans, rivers and lakes), air, soil, drinking water, food, marine animals, earthworms (1), human urine and faeces (1, 3).

How do they get there?

  • Water: MPs used as additives on personal care products find their way down the sink and into water treatment plants (2).
  • Compost: Some plastic escapes sorting processes in compost and make it into the final product (2). This is relevant because compost is used in farm soil, which means MPs and NPs can make their way into food grown for animal and human consumption.
  • Landfill: All the non-degradable plastic that ends up in landfill is exposed to environmental conditions over a long period of time that can facilitate its degradation and leaching into the environment (2).
  • Land to sea transfer: MPs and NPs can make their way from land to the sea via erosion and run-off (2).
  • Marine activities: Boats, ropes and fishing nets also leach MPs and NPs into the ocean (2).

How to they get into humans?

  • Seafood: MPs and NPs are most commonly found in the digestive tracts of fish and seafood. Therefore, we are exposed to them when eating small fish and seafood that are eaten whole such as small fish and shellfish (e.g. clams, mussels, oysters). In addition, MPs and NPs have also been found in the flesh of some fish species we eat (2, 3).
  • Other food: MPs and NPs have also been found in beer, honey, sugar, salt, bottled and tap water (2, 4, 5). Pigs (and potentially other livestock) can be exposed to MPs and NPs through feed which includes seafood viscera and/or soil (3). Finally, fruits and vegetables can accumulate MPs and NPs from soil (5, 6).
  • Air: We are also exposed to MPs and NPs from the air we breathe (2).
  • Absorption through the skin: This is not a confirmed but nevertheless plausible route of exposure to MPs and NPs (3).

References

  1. Jiang B, Kauffman AE, Li L, McFee W, Cai B, Weinstein J, et al. Health impacts of environmental contamination of micro- and nanoplastics: a review. Environ Health Prev Med. 2020 Jul;25(1):29.
  2. Bradney L, Wijesekara H, Palansooriya KN, Obadamudalige N, Bolan NS, Ok YS, et al. Particulate plastics as a vector for toxic trace-element uptake by aquatic and terrestrial organisms and human health risk. Environ Int. 2019 Oct;131:104937.
  3. Zarus GM, Muianga C, Hunter CM, Pappas RS. A review of data for quantifying human exposures to micro and nanoplastics and potential health risks. Sci Total Environ. 2021 Feb;756:144010.
  4. Barboza LGA, Dick Vethaak A, Lavorante BRBO, Lundebye A-K, Guilhermino L. Marine microplastic debris: An emerging issue for food security, food safety and human health. Mar Pollut Bull. 2018 Aug;133:336–48.
  5. Campanale C, Massarelli C, Savino I, Locaputo V, Uricchio VF. A Detailed Review Study on Potential Effects of Microplastics and Additives of Concern on Human Health. Int J Environ Res Public Health. 2020 Feb;17(4).
  6. Oliveri Conti G, Ferrante M, Banni M, Favara C, Nicolosi I, Cristaldi A, et al. Micro- and nano-plastics in edible fruit and vegetables. The first diet risks assessment for the general population. Environ Res. 2020 Aug;187:109677.

[Photo by Naja Bertolt Jensen on Unsplash]

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