What is known and unknown concerning microplastics from tyre wear?

Abstract

Pollution of the environment by microplastics is a problem that is increasingly visible and worrisome, with tyre wear particles (TWPs) being considered, after several studies, as one of the major sources of microplastics. The aim of this paper is to present a review of the current knowledge on microplastics generated by road traffic, more specifically in TWPs. Generation and pathways depend on different factors like characteristics of the tyre and road or physical properties of the particles, among others. Currently, there are some studies on TWPs, both, carried out at the laboratory and under real scale conditions. So far, it has been possible to identify the presence of TWPs in samples, but their quantification involves time-consuming and expensive methods. The big knowledge gap is to find a standardised and practical method for sampling, detection and quantification, so more research on TWPs and their dispersion in the environment is needed.