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Plastics in our Bodies

Due to their poor biodegradability and inadequate recycling, plastics have exponentially been found… everywhere. And by everywhere I mean: inside our bodies, most likely since the day you were born. It has become a fact that right now there are thousands, if not millions of microplastics travelling through your blood and living in your organs comfortably and cosily. But how can this be, and in what ways does this affect us?



What are (micro)Plastics?

First of all, what are plastics? Well, plastics are primordial constituents in our day to day lives due to their affordable price and prominent physicochemical properties. In 2018, global plastic production increased to more than 260 million tonnes and is expected to triple said amount by the year 2050 -PlasticsEurope. The ubiquitous presence of plastics, specifically their polymer derived particulates defined as micro and nano plastics are the ones which currently inhabit our bodies.


Microplastics are those fragments of plastics of sizes smaller than 5 mm. For reference, a grain of rice is 6mm. Moreover, these are further diminished into nanoplastics, of size under 1 nanometer. Plastics are constructed from a long chain hydrocarbon called Napths, or more specifically, many ethylene monomers together forming polyethylene ( as well as polyvinyl chloride and polypropylene forming the 3 most commonly used plastics). This is what makes them not biodegradable as organic substances (e.g. fungi)do not contain the enzyme required to digest their bonds due to their man-made nature.


Moreover, its strong carbon-carbon bonds makes it very inert, thus making it hard to decompose by many acids and bases; inevitably just breaking into increasingly smaller fragments (microplastics), which remain in the environment as waste. In 2019, 460 million tonnes of plastics were produced and only 9% was recycled. So, plastics are everywhere around us, but how can they find their way inside us?



Next station: inside our bodies

Researchers in both Germany and Brazil state that 8/15 adults autopsied had microplastics detected within brainial smell centres, eg the olfactory bulb. This is due to the possibility of entering us via two routes:


  1. Ingestion

  2. Inhalation


  1. Ingested plastics emerge from eating food and or drinks stored in plastic containers. This was further proven by a study from 2019 where they observed 10 different water bottles and tested for microplastics within the water; all 10 came out positive. (Zuccarello, P., Ferrante, M., Cristaldi, A., Copat, C., Grasso, A., Sangregorio, D., Fiore, M. and Oliver Conti, G. (2019). Exposure to microplastics (<10 μm) associated to plastic bottles mineral water consumption: The first quantitative study. Water Research, 157, pp.365–371. doi:https://doi.org/10.1016/j.watres.2019.03.091.) Later on were microplastics found in lungs, intestines and even testes and sperm (Yang et al. 2022b; Zhao et al. 2023a) which just further proves that microplastics can cross high pressure blood-tissue barriers due to their tight junction. Another example of this is the blood brain barrier, which initially seemed to retain microplastics filtered out of the brain. However, just like sneaky rodents, they found another way.


  1. Plastics smaller than 500 micrometres are light enough to be swept by the air and inhaled by us. Sources of these are car tires, synthetic clothing, paint-base markings… For example, car tyres erode with the road. These then fly away thanks to the uplifting wind currents formed by passing cars.


They enter via the olfactory bulb (according to the team lead by Luis Fernando amaro-lourenco) as an almost involuntary response. The Nasal mucosa lying outside the brain could interact with cerebrospinal fluid, hence allowing the entry of microplastics via minuscule perforations in bony structures around the area.


So, next question: Once they have either been ingested/inhaled, how does our body deal with these miniscule penetrators? (Next station: you)



Right here, Right now

After they have entered our bodies they can either be excreted or preserved. Yes I know, what an uncomfortable sensation. This is defined as “biopersistent”, meaning that they will forever stay in the body as it disposes of no enzymes which can break them down.


  • At 100 micrometres or less: microplastics can become permanently lodged in organs within your body.

  • At 10 micrometres or less: they can penetrate the cell membrane and alter cell activity.


Don’t believe me? Here is some science to prove the horror by:


The most predominant polymer (polyethylene) was found in significantly greater amounts than all others in tissues. It demonstrated (independently) an increase over 74% between 2016 and 2024 in the brain and 44-47% in the liver and kidney, (confirmed from 5 brain samples.) From another 15 samples, nearly 44% of cases the plastic was


“What is worrying is the capacity of such particles to be internalised by cells and alter how our bodies function,” Mauad added. Moreover, internal concentrations of microplastics increase as those of microplastics outside increase - total plastic mass concentrations in brains increased over 50% in the past 8 years!


Even more experiments concluded the microplastic concentrations in deceased brain samples ranged between 7 to 30 times the concentrations seen in liver or kidneys , increasing global rates of age-corrected Alzheimer’s as well as related dementia - but that’s another forthcoming station…



In plants

Microplastics, surprise surprise, are also found in the soil! These are then taken up by the plant through two pathways: roots and foliar (through stomata). After they’ve passed through the plant cell wall and travel via translocation along the plant to the plant leaves, they are stored by the plant until ingested by other organisms as (like us) they cannot break them down.



And finally…THE EFFECTS

Truthfully, experts aren’t really sure yet about the effects of microplastics in the human body. They have, however, illustrated a rough sketch…


These ideas sprout, for example, by the way in which cells release certain proteins as an inflammatory response when in contact with these microplastics. This could be either as a response to their toxicity or due to their foreign nature. Ultimately, this is consecutive inflammation, slow and chronic, and could develop diseases such as cancer and autoimmune.


They have also been found to alter the memory and behaviour of organisms - leading to nervous system inflammation contribution as well as neurodegenerative disorders. Moreover can they also interfere with various hormone receptors, subsequently disrupting different hypothalamic axes… such as the hypothalamic-pituitary-thyroid axis [HPT], the hypothalamic-pituitary-adrenal axis [HPA], and hypothalamic-pituitary-gonadal axis. Studies in rats whose direct correlation of various metabolic disorders such as gut dysbiosis and intestinal barrier dysfunction are induced by microplastics as similarly disrupted thyroid status and biochemical stress as symptoms of neurobehavioral changes. Microplastics act as carriers, and can inevitably be even more harmful when mixed with other pollutants e.g. absorbed in water due to high their SA to volume ratio.



Last stop: SOLUTIONS

Even Though it all seems very overwhelming due to the grand scale ofthe situation, we must work as much as we can individually to abate plastic presence. Our micro-contribution to a mega-plastic problem:

  • Use natural and biodegradable materials: examples are recycled clothing, cork bags, bamboo toothbrushes.

  • Cotton wool clothing: instead of synthetic fibres.

  • Homemade face scrubs and soaps

  • Stainless steel bottles and cutlery


We are at the nano-startline.

At the very micro-beginning of understanding.

We must find out now what we can do to Mega solve it.



Blanca de H, Y12

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