Microplastics, an unknown future

Microplastics, until relatively recently, were an unknown topic. They were first described in the 70s, but the interest in studying them did not arise until the early 2000s. This makes all of us who are not experts in the subject ask ourselves: Are they dangerous for us?

What are microplastics?

Microplastics are plastic pieces with a diameter of less than 5 mm1 .These particles have diverse sources: there are primary particles (created for a purpose, such as in cosmetics) and secondary ones (product of the fragmentation of larger plastics).

Secondary microplastics comprise a wide variety of plastic types with completely different compositions. Because of this high diversity of origin and composition, it is difficult to group them into a single category, which makes it hard to generalize about microplastics.

The primary source of secondary microplastics is from plastic garbage along coastlines that are broken down over time by the sun. For this reason, plastic waste found on beaches or rivers is more likely to makes its way into the ocean and turn into microplastics 2.

Therefore, cleanups of plastic waste on beaches, coastlines, or along rivers can help prevent higher production of microplastics from improperly managed plastic

An additional source of microplastics in the environment are microfibers, which are formed from the shedding of synthetic fibers, like polyester and acrylic, from clothing and other fabrics.

 

What do we know about microplastics?

Microplastics are such an emerging field of science that they are still in a grey area regarding their toxic / harmful potential. What we do know is that they are everywhere 3, even in Antarctica 4.

This then begs the question, are we eating them? The short answer is yes. In a recent unpublished dataset, microplastics were found in in human feces 5. However, all we can know for sure based on these findings is that there is no risk of obstruction after ingesting them, as they are eliminated fecally without problems.

Nonetheless, a lot of controversy remains about their supposed toxicity and the associated health problems they may cause. This is in no small part due to the additional finding that polystyrene microspheres can get through the gut cells in some mammal models, which would imply their access into the organism6.  In this scenario ingested microplastics could likely lead to possible health problems7,8. As I have mentioned in other posts, plastic is a complex material, with many additives. Therefore, the so-called toxicity of microplastics will depend on their individual composition and will ultimately be multifactorial2, though it can be more or less generalized into the following three sources:

  • Residual monomers present at the time of production (as the famous BPA)
  • Toxicity associated with the partial degradation of the material (for example, burning polystyrene can release aromatic compounds).
  • Persistent Organic Pollutants (POPs) that are toxic chemicals, which are classified as pesticides, organochlorine insecticides, herbicides..

So, are they dangerous?

So far, microplastics have not turned out to pose a short-term risk to human health, but they surely don’t benefit us either. Irrational fear with no scientific basis is never warranted, so until we reach some conclusive answers from the scientific community we will simply have to stay calm and wait.

However, the concentration of microplastics is growing higher as plastic production increases and reaches all areas of the Earth. That is why, despite our lack of toxicity data, this does not exempt us from the need to reduce the production, distribution and improper disposal of plastics.

It is undeniable that the use of limited resources for the unlimited production of derived materials is not feasible in the long term. The greenhouse gases released during the extraction, processing, manufacturing and distribution of plastic items that will then only be used for 10 minutes before being thrown away is a significant part of the problem.

With all that being said, this is our take-home message:

Are we really going to wait for proof of their health hazard to start to reduce their use?

Team work is always better

This post was a collaboration with Laura Markley, who is a PhD Student of Civil and Environmental Engineering at Syracuse University. We invite you to follow her in instagram and subscribe to her blog Waste-free PhD. She addresses scientific topics related with zero waste under her moto “research, reduce, recycle” .

References

  1. Arthur, Courtney; Baker, Joel; Bamford, Holly (Enero de 2009). «Proceedings of the International Research Workshop on the Occurrence, Effects and Fate of Microplastic Marine Debris». NOAA Technical Memorandum.
  2. Andrady, A. L. (2011). Microplastics in the marine environment. Marine pollution bulletin62(8), 1596-1605.
  3. D.K.A. Barnes, F. Galgani, R.C. Thompson, M. BarlazAccumulation and fragmentation of plastic debris in global environments Philos. Trans. R. Soc. B, 364 (2009), pp. 1985-1998
  4. C. Zarfl, M. MatthiesAre marine plastic particles transport vectors for organic pollutants to the Arctic? Marine Pollution Bull., 60 (10) (2010), pp. 1810-1814
  5. Pappo, J., & Ermak, T. H. (1989). Uptake and translocation of fluorescent latex particles by rabbit Peyer’s patch follicle epithelium: a quantitative model for M cell uptake. Clinical and experimental immunology76(1), 144.
  6. Micro- and Nano-plastics and Human Health Tamara S. Galloway
  7. Polystyrene microplastics induce gut microbiota dysbiosis and hepatic lipid metabolism disorder in mice. Author links open overlay panel. Liang Lu, Zhiqin Wan, Ting Luo, Zhengwei Fu, Yuanxiang Jin. Science of The Total Environment Volumes 631–632, 1 August 2018, Pages 449-458

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