**Abstract**

Plastics have been critical in human development due to their unique properties. However, when discarded, they accumulate in the natural environment due to their lack of biodegradability and when exposed to environmental conditions, these polymers become microplastics (MPs). Many experimental studies have detected MPs in the environment, but the identification and separation methods used, work for certain types of MPs while overlooking or damaging others, which can affect the development and application of systematic risk evaluations such as the ecological risk assessments (ERAs). A literature review was conducted of papers published up to 2021 looking for ERAs made for MPs on experimental studies. The eight selected articles were analyzed and scored based on concentration, toxicology, and quality assurance (QA) criteria. The hazard index (HI), the pollutant load index (PLI), the potential ecological risk index (RI), and the risk quotient (RQ) based on species sensitivity distribution (SSD) were compared and assessed. To compare the indexes correctly, modifications were made to previous studies.

**Keywords:** microplastics, polymer, environmental risk assessment, risk, comparison, review
