Microplastics: Environmental Occurrence and Analytical Challenges

Plastic pollution is a major societal, economic, and environmental issue. Upon release into the environment, plastics are altered by biological and physicochemical processes that influence their fate and transport within ecosystems. Large plastic debris can fragment into smaller pieces and are called microplastics (MPs) when occurring at sizes between 1 µm and 5 mm, fragmented or produced in this range. These small pieces of plastics are ubiquitous anthropogenic contaminants found throughout the world; however, the environmental consequences and effects on biota are not clearly understood. Scientific literature on the environmental implications of MP pollution is expanding rapidly and critical review of this literature is necessary to identify areas of evolving consensus and remaining gaps in knowledge. Herein a comprehensive literature review was performed to assess (i) the sources and distribution of MPs in different environmental compartments, (ii) the analytical methods that have been applied worldwide, and the key analytical challenges that remain in assessing MPs in the environment, and, finally, (iii) to integrate the findings of Brazilian MP research, which showed that since 2004 (80 papers up to 2020) has documented the presence of MPs in aquatic matrices and sediments with focus on marine ecosystems, mainly identified by visual inspection.