Based on the paper Frias & Nash (2018), microplastics are defined as “synthetic solid particles or polymer matrices, with regular or irregular shapes and with sizes ranging from 1 mm to 5 mm, both primary and secondary products originating from manufacturing and insoluble in water.”
The amount of microplastics is very large and has also spread throughout the world, especially in the last 70 years. The distribution and quantity of microplastics are so large that they even make their own stratification layers in soil or rock, therefore many scientists have made microplastics a separate epoch: Plasticene (Campanale et al. 2020). However, the impact of microplastics is not fully understood, especially their impact on human health. This is due to the very complex physical and chemical properties of microplastics. Microplastics consist of two types of chemical compounds, namely 1. Additive compounds and raw polymer materials (including reinforcing materials, plasticizers, antioxidants, UV stabilizers, lubricants, dyes and flame retardants) and 2. Chemical compounds that are absorbed from the environment. It is feared that microplastics can enter the food chain, accumulate, and are consumed by humans through biomagnification. The idea of biomagnification comes from Rachel Carson’s book entitled “The Silent Spring” about the accumulation of DDT compounds which causes chicken and eagle eggs become thin-shelled and causes the death of these eggs.
Biomagnification is “the process by which xenobiotic substances (chemical compounds that are naturally absent in organisms) are transferred from organisms to other organisms in the food chain resulting in a higher concentration compared to their source.” (Rand et al., 1995). Although the biomagnification phenomenon is used to explain the accumulation of chemical compounds in food webs, microplastics which are physical objects are also assumed to have the same pattern. Microplastic is one of the xenobiotics that many researchers have started to research as a result of the increasing number and distribution of plastics in the environment over the last few years (Gray, 2002).
From the research of Saley et al. (2019) in the journal marine Pollution Bulletin, the accumulation of microplastics even occurs in the food chain in coastal ecosystems that are far from humans, these microplastics are found in high concentrations in aquatic herbivore populations (especially snails). If, in remote aquatic ecosystems, microplastics can accumulate to detectable concentrations, aquatic ecosystems with a closer distance to human populations are assumed to have more microplastics.
Based on research by Miller et al. (2020) in the journal Plos One, microplastics have accumulated and are present at all levels in the food web in aquatic ecosystems, especially in the ocean. Although there is no indication in the field that the accumulation of microplastics that occurs in living things is biomagnification. Still, it cannot be denied that microplastics exist in freshwater and marine animals that we consume, even in land animals.
Research on the dangers of microplastics on human health has become common. Although there are no conclusive results from these studies, there are indications that microplastics are harmful to the human body because they are toxic to cells in the body. Aside from that, microplastics can be carriers of microorganisms or other compounds, like heavy metals, which have bad effects to human health. Microplastics can enter the human body through digestion, inhalation, and in contact with the skin.
Microplastics can enter the digestive system through food and it can adversely affect the digestive system and excretory system. Based on the research by Barboza et al. (2018), microplastics with a size of 10 µm can enter cell membranes, organs, and the placenta. In addition, microplastics smaller than 2.5 µm can enter the digestive tract through endocytosis by M cells. The entry of microplastics into the gastrointestinal tract can cause poisoning caused by inflammation. The severity of inflammation is influenced by the concentration of microplastics in the digestive tract. In fact, the human excretory system is capable of removing up to 90% micro and nano plastics (Campanale et al. 2020). Even so, more than 10% of the rest can still cause inflammation.
Microplastics are also present in the air, which can come from waste processing sites, synthetic clothing, industrial emissions, dust, and agriculture. These microplastics can enter the respiratory system through the air and it can adversely affect the respiratory system. The effects of these microplastics vary depending on susceptibility, dose, and body metabolism, but some people can develop asthma, pneumonia, inflammation, bronchitis, and even pulmonary cancer (as found in employees in the textile industry) (Campanale et al. 2020). In addition, there is another danger of possible transmission of microorganisms to the respiratory tract from adhering microorganisms to microplastics.
Microplastics can also enter the skin through physical contact with the skin when washing the skin with water or from cosmetics. However, only microplastics that are less than 100 nm in size can enter. These microplastics contain organic pollutants, antibiotics, and heavy metals which have high cytotoscity (the level of damage to a substance in cells) (Campanale et al. 2020). For example, there are aluminum and antimony metals which can cause breast cancer and manganese metal which can cause abnormalities in the nervous system.
The details of the dangers of microplastics and their effects on the human body have not been widely studied. It could be that microplastics are more dangerous to human health than previous studies. Therefore, it is very important for us to reduce plastic waste so that the distribution and amount of microplastics in rivers and oceans can be reduced and it does not endanger human health and other living things.
Greeneration Foundation is also preventing microplastic on waterways through Citarum Repair program to help solve the problem of garbage in the Citarum River and also help educate residents around the Citarum River regarding plastic, river and sea waste.
Barboza, L. G. A., Vethaak, A. D., Lavorante, B. R., Lundebye, A. K., & Guilhermino, L. (2018). Marine microplastic debris: An emerging issue for food security, food safety and human health. Marine pollution bulletin, 133, 336-348.
Campanale, C., Stock, F., Massarelli, C., Kochleus, C., Bagnuolo, G., Reifferscheid, G., & Uricchio, V. F. (2020). Microplastics and their possible sources: The example of Ofanto river in Southeast Italy. Environmental Pollution, 258, 113284.
Frias, J. P. G. L., & Nash, R. (2019). Microplastics: finding a consensus on the definition. Marine pollution bulletin, 138, 145-147.
Gray, J. S. (2002). Biomagnification in marine systems: the perspective of an ecologist. Marine Pollution Bulletin, 45(1-12), 46-52.
Miller, M. E., Hamann, M., & Kroon, F. J. (2020). Bioaccumulation and biomagnification of microplastics in marine organisms: A review and meta-analysis of current data. Plos one, 15(10), e0240792
Rand GM, Wells PG, McCarty LS. Introduction to aquatic toxicology. (1995). In: Rand GM, editor. Fundamentals of aquatic toxicology: Effects, environmental fate, and risk assessment. North Palm Beach: Taylor & Francis. pp. 3–67
Saley, A. M., Smart, A. C., Bezerra, M. F., Burnham, T. L. U., Capece, L. R., Lima, L. F. O., … & Morgan, S. G. (2019). Microplastic accumulation and biomagnification in a coastal marine reserve situated in a sparsely populated area. Marine pollution bulletin, 146, 54-59.