Pollution from micro- and nanoplastics currently represents one of the main environmental challenges, raising concerns both for its ecological consequences and for the potential risks to human health. After two decades of data collection since the first appearance of the term “microplastic” in the scientific literature, research is moving toward a new direction—that of assessing ecological and human health risks. In this perspective, a rising interest is converging on the use of indices, which may represent an effective tool for describing environmental quality in a clear and straightforward manner.

This contribution, based on the systematic review of 316 papers collected from the Web of Science database, aims to examine the use of indices for environmental risk assessment from both an editorial perspective (when the first publication dates back to, how the topic has evolved over time, and which publishers and journals have shown the greatest interest) and a technical point of view (which and how many indices have been proposed to date, which environmental matrices have been considered, and which geographical areas have received the most attention). Furthermore, what limitations does each index present, and how can they be improved? The goal is to gather and summarize all information on the topic, which to date remains somewhat fragmented, and propose a roadmap to guide researchers and practitioners through an informed, accurate, and standardized use of indices for ecological risk assessment of microplastic pollution.