The Microplastics Iceberg: Filling Gaps in Our Understanding

Abstract

Plastic is an indispensable material in modern society; however, high production rates combined with inadequate waste management and disposal have resulted in enormous stress on ecosystems. In addition, plastics can become smaller particles known as microplastics (MPs) due to physical, chemical, and biological drivers. MP pollution has become a significant environmental problem affecting terrestrial and aquatic ecosystems worldwide. Although the topic is not entirely new, it is of great importance to the field of polymers, drawing attention to specific gaps in the existing literature, identifying future areas of research, and improving the understanding of MP pollution and its environmental impacts. Despite progress in this field, problems remain. The lack of standardized methods for MP sampling, separation, extraction, and detection makes it difficult to collect information and establish links between studies. In addition, the distribution and pathways of MPs in ecosystems remain unknown because of their heterogeneous nature and the complex matrices in which they occur. Second, toxicological tests showed that MPs can be ingested by a wide range of organisms, such as Danio rerio and Eisenia fetida, resulting in gut obstruction, physical damage, histological changes, and oxidative stress. The uptake of MP and their toxicological effects depend on their shape, size, concentration, and polymer composition. Furthermore, MPs can enter the food chain, raising concerns regarding potential contaminations for human and environmental health. This review paper sheds light on the pressing issue of MP pollution and highlights the need for interdisciplinary collaboration between scientists, policymakers, and industry leaders.

Keywords: analytical methods; ecotoxicity; emerging contaminants; oxidative stress; plastic pollution.

Figure 1

Types of plastic debris found on a beach in Northern Portugal. The plastic materials include: (a) a plastiglomerate, (b) mesoplastic fragments, (c,d) microplastics.

Figure 2

Sources and routes of microplastics and plastic-related chemical pollution in soil environment.

Figure 3

The main steps involved in analysing microplastics in environmental samples: pretreatment, extraction, and identification.

Figure 4

Factors that lead to the ingestion or absorption of microplastics causing potential ecotoxicological and toxicological impacts.