Perhaps the single most ubiquitous material in the world right now is plastic, and more specifically, microplastics. Microplastics, pieces of plastic smaller than 5 millimeters in length, can be found practically anywhere in the world. They have been found in the oceans, in the soil, and in the air. They have been found in places untouched by human civilization—from polar ice masses to the depths of the Mariana Trench [1]. These microplastics, being so widespread and hard to avoid, may have health consequences that are not well-known or studied.
Since 1907, when the first plastic was manufactured, the plastics industry has only continued to grow [2]. According to Verla et al., 0.35 million metric tons of plastic were manufactured in 1950, and in 2017, 348 million metric tons were manufactured [2]. These production numbers only increase as the demand for plastic continues. Being a resistant material relative to its weight and cost to manufacture, plastic is now everywhere in the daily lives of people worldwide.
Macroplastics, pieces of plastic larger than 5 millimeters in length, are often noted as a key environmental pollutant. They are known to harm animals, disrupt ecosystems, and accumulate in large patches in coastal areas and the ocean [3]. Environmental processes can fragment these macroplastics into smaller pieces called microplastics. In addition to being produced from the degradation of macroplastics, microplastics are also often intentionally produced for use in cosmetics and wastewater treatment [2]. As aforementioned, microplastics are incredibly widespread to the point where they are the most plentiful solid waste in the world [1].
Given how widespread microplastics are, their ingestion is difficult to prevent. Microplastics have been found in various types of food and beverages such as bottled water, fruits, and vegetables [1]. The dangers of ingesting microplastics are not particularly well-studied, but research supports the idea that microplastics negatively affect humans in three ways: chemically, physically, and biologically.
Since microplastics have a high surface area relative to their volume, they are very good at absorbing toxic chemicals including heavy metals such as arsenic, cadmium, chromium, copper, and manganese [2]. Other chemicals that can be absorbed by microplastics include pesticides and other persistent organic pollutants. According to Campanale et al., such chemicals are known to be toxic, mutagenic, or carcinogenic, effects that are very detrimental to human health [4]. Physically, microplastics can cause damage as well. If inhaled, microplastics cannot be cleared from the respiratory system, causing inflammation or respiratory lesions. Similar issues can arise in the gut following the ingestion of microplastics [2]. In addition to the toxic chemicals that they can carry, microplastics can also carry organisms like bacteria, leading to harmful infections [5]. An increase in these microorganisms can create antibiotic-resistant bacteria on microplastics, which like other chemicals, can be absorbed into microplastics. Furthermore, the combination of bacteria and antibiotics can lead to dangerous enhanced superbugs [1]. The number of ways microplastics can negatively affect human health is concerning.
Research on microplastics is a fairly recent venture, meaning there is still much that is not known about the direct effects of microplastics on human health. Much more study is needed to understand the issues microplastics can cause and to identify ways to remedy these issues. Some scientists recommend reducing waste at the source, treating waste in a way that does not release microplastics, and using plastic that can be readily biodegraded. Further research is needed to identify more specific and effective solutions, but it is known that microplastics are found in what we eat, what we drink, and what we breathe, and that the properties of microplastics make them more prone to carry toxic chemicals and microorganisms. Something so prevalent, yet with effects so unknown, certainly requires more investigation.
References
Blackburn, K., Green, D. The potential effects of microplastics on human health: What is known and what is unknown. Ambio 51, 518–530 (2022). https://doi.org/10.1007/s13280-021-01589-9
Verla, A.W., Enyoh, C.E., Verla, E.N. et al. Microplastic–toxic chemical interaction: a review study on quantified levels, mechanism and implication. SN Appl. Sci. 1, 1400 (2019). https://doi.org/10.1007/s42452-019-1352-0
Thushari, G., & Senevirathna, J. (2020). Plastic pollution in the marine environment. Heliyon, 6(8), e04709. https://doi.org/10.1016/j.heliyon.2020.e04709
Campanale, C., Massarelli, C., Savino, I., Locaputo, V., & Uricchio, V. F. (2020). A Detailed Review Study on Potential Effects of Microplastics and Additives of Concern on Human Health. International journal of environmental research and public health, 17(4), 1212. https://doi.org/10.3390/ijerph17041212
Amelia, T.S.M., Khalik, W.M.A.W.M., Ong, M.C. et al. Marine microplastics as vectors of major ocean pollutants and its hazards to the marine ecosystem and humans. Prog Earth Planet Sci 8, 12 (2021). https://doi.org/10.1186/s40645-020-00405-4