# The Microplastics Cycle: An In-Depth Look at a Complex Topic
###### Abstract  
Microplastics, or plastic particles smaller than 5 mm in size, have become ubiquitous in the environment, found in places ranging from remote deep ocean trenches to minute dust particulates. From the breakdown of larger plastic products and the release of synthetic clothing fibers, these particles enter the ecosystem and cycle through the various components including aquatic, terrestrial, and human systems. Due to their durability, capacity to adhere to other toxic compounds, and potential effects on humans and ecosystems, microplastics have recently risen to the forefront of environmental and health concerns. To address these critical issues, there has been a surge in research related to the microplastics cycle, examining where they originate, how and where they travel, and their environmental and human health impacts. Research on the microplastic cycle is often broken down into its various individual components such as sources, fate, and effect, and further scattered through the literature are focuses on specific environments such as land, oceans, and freshwater, as well as on human health. Here, we review the current state of the literature on the microplastics cycle across its various environmental reservoirs. In-depth examination of the microplastics cycle is necessary for understanding the scope of the problem and developing viable solutions or mitigation strategies, such as reducing plastic production and promoting recycling. Understanding the complex microplastics cycle is an urgent issue that necessitates multidisciplinary research and action.  
microplastics; plastic pollution; micro-particles; microbeads; plastic waste; persistence; contaminants; environmental impact; human health; food chain; ecosystems +
Footnote †: journal: _sciences_  
Additionally, there is a lack of consensus, yet an identified need, regarding standardized methods for monitoring, collecting, and quantifying microplastics from the environment (e.g., soil, sediment, water, biota). Eventually, standardized field and laboratory techniques will allow for global comparisons of the amount of microplastics in the environment, which is the first step in determining the eventual distribution, and the consequences of this debris. Plastic litter, like climate change and persistent organic pollutants, is yet another troubling example of human impacts on the global biosphere. According to [PERSON] et al. [9], marine plastic pollution is irreversible and pervasive on a global scale. Therefore, it meets two of the three requirements for a global threshold hazard, except that the disruptive effect is not identified until it is a global problem [10].  
In the realm of microplastics research, the majority of published studies, comprising 61% of the corpus, have been dedicated to investigations within the marine environment. Conversely, only 39% of these studies have focused on the freshwater environment. Utilizing the comprehensive Web of Science Core Collection database, our search strategy entailed querying for the keyword \"microplastics\" within the title, abstract, author-defined keywords, and keywords. Our search spanned up to the year 2022, encompassing a substantial compilation of 11,947 research papers. As illustrated in Figure 1, the trajectory of publications on microplastics exhibits a remarkable and consistent upward trend over the years, demonstrating a substantial surge from 1986 to 2022. While numerous papers have been published on the examination and assessment of microplastic levels in water sources, these studies often indicate that the detected quantities may not have a significant impact on the metabolism of biological organisms. What is even more intriguing is the question of whether this relatively low quantity of microplastics can indeed make a substantial difference over the long term. Many of the research findings related to the impact of microplastic contamination on aquatic organisms tend to focus on short-term effects.