What are microplastics?
The first time the accumulation of small plastic granules in the environment was noted dates back to the early 1980s, but it was only in 2004 that Thompson et al. coined the term “microplastics”. Today, the commonly accepted definition of microplastics is the one given by the European Chemicals Agency (ECHA), wherein it states that microplastics are “solid plastic particles composed of mixtures of polymers and functional additives.”
Microplastics can form accidentally, i.e. through abrasion, or be added to food deliberately in order to achieve certain characteristics. According to the European Food Safety Authority (EFSA), microplastics range in size from 0,1 – 5000 μm, whereas nanoplastics are 1 – 100 nm in size.
Where are microplastics found?
In studying microplastics it can unfortunately be concluded that they are unavoidable. Microplastics can come from floor abrasion, furniture and textiles, cosmetics intended for personal use (lip glosses, toothpastes containing microgranules, shower gels and facial cleansers doubling as a peeling agent), various paints, artificial sports surfaces, products containing glitter, and 3D printing. In fact, plastic materials can also be airborne. An analysis of dust and air in households has shown the extent of domestic microplastic pollution, which poses a health and hygiene issue. One of the largest sources of microplastics in the world is automobile tyre abrasion.
Various research conducted in the last 5 years has proven the existence of microplastics in 128 samples of table salt from different distributors in 38 countries around the world. It has also been found in bottled drinking water, where its source are bottle caps. Beer, energy drinks and other beverages also contain microplastics, and so do fruit and vegetables – in the pulp as well as the rind. The existence of plastic microbeads has been confirmed in more than 60% of coastal surface water (So et al., 2018.). Microplastics have also been found while examining soil quality. The atmosphere, food and water are all contaminated with microplastics.
How do microplastics affect our organism?
This all begs the question: to what extent are people exposed to microplastics and how does it affect the human body? The most common intake pathways are through the gastrointestinal and respiratory systems as well as through skin, but due to the small size of microplastic particles, translocation to other tissues is possible as well. For example, the presence of microplastic particles has been proven in kidneys and placenta.
While there is not enough research conducted using humans as a model organism, various research conducted on other model organisms has demonstrated the effects of microplastics on a living organism. The very presence of microplastics in an organism has an abrasive effect which leads to inflammation, oxidative stress and cytotoxicity. The chemical effect of microplastics arises from the release of additives and/or chemicals adsorbed from the environment, which leads to reproductive and developmental toxicity, as well as an immune response. Bacteria can adhere to microplastic particles and form a biofilm, therefore acting as a pathogen in the organism and causing an infection and/or gut microflora dysbiosis. These bacteria can be antibiotic resistant, which makes these infections hard to treat and even life-threatening. In fact, antibiotics themselves can be adsorbed onto microplastic particles which then make their way into the organism.
Taking into account that the general populace breathes in multiple hundred microplastic particles a day on average, intake through inhalation is an even more concerning pathway. The inhalation of plastic fibres leads to respiratory disease, inflammation and oxidative stress; the textile industry poses the biggest danger.
Based on data collected throughout 10 years of research, it has been concluded that microplastics as well as nanoplastics exhibit cardiotoxic properties; direct cardiac toxicity includes abnormal heart rate, impaired cardiac function, pericardial edema and myocardial fibrosis. On a microvascular level, microplastic particles lead to haemolysis, thrombosis, blood coagulation and vascular endothelial damage. On a molecular level, the aforementioned particles cause oxidative stress, inflammation, apoptosis and pyroptosis, as well as interacting with cellular structures.
The future and microplastics
The actual concentration of microplastics accumulated in the human body is not yet known. A detailed inquest into the effect of microplastics on human health, especially its effect on inflammation and cellular damage, is yet to follow. The focus is also on using various methods to purify urban water systems and cleanse them of micro- and nanoplastic pollution.
Translated by: Anđela Jakiša
Literature
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