**4. Conclusions**

The present review highlights the need to adequately create an environmental risk analysis for MPs, as it allows for better and simpler comparisons between studies, a way to communicate the hazards of MPs to society, and a basis for future regulations. The approaches used by the authors of the reviewed articles can serve as a foundation for future risk analysis. Still, they have some limitations, such as not including all the ways in which a MP can be toxic, not including all the uncertainties in the statistical analysis of SSD, not indicating the differences in their experimental methodologies (that generate difficult-to-compare articles), and others. Some corrections were made to the reviewed articles to determine more comparable parameters. In every case, significant variations were obtained due to the difference in the detection methods used or the studied waterbody.

The most integral approach is the one in which the RQ or PNEC values are estimated based on an SSD, because the toxicological studies included many types, sizes, shapes, and concentrations of MPs, as well as several control species. In the future, this approach may narrow the toxicological studies used as mentioned above and with the aid of statistics will probably become more and more accurate overtime. The least complete approach is the one based on the toxicity of the monomers as it does not consider any other toxicological aspects of the MP.

The article also highlights the importance on the reporting of the MPs detection methodology and the importance of QA in experimental articles.

Other authors may use this article to identify some key parameters to make comparisons between experimental articles and risk analysis of MPs.
