A review of rubber tyre derived micro- and nanoplastics: fate, impact and risks

Micro- and nanoplastics generated by friction- and traction-induced wear and tear of rubber tyres, designated as tyre microplastics (TMPs) and tyre nanoplastics (TNPs), are a major source of air, terrestrial and aquatic contamination. These particles are dispersed from the point of generation to distant locations via wind action and stormwater and wastewater discharges, adding to the particulate matter load in ambient air, and resulting in river and marine flora and fauna contamination. The occurrence of TMPs and TNPs in the environment is widespread, persistent and unregulated. This paper critically assesses current scientific knowledge on TMPs and TNPs by conducting a systematic review of their occurrence, methods of identification and characterisation, and knowledge gaps related to their fate, transport and environmental impacts. Their fate primarily depends on the particles’ size, shape, density, composition and possible interactions with living organisms and plants, along with processes like fragmentation, aggregation, sorption and bioaccumulation. These particles also have the potential to leach heavy metals and aromatic hydrocarbons, causing detrimental impacts on aquatic/terrestrial organisms. The lack of standardised methodologies for identification, quantification and characterisation of TMPs/TNPs poses significant challenges in terms of wider environmental risk assessment, while their sources, emissions, transport and impacts remain highly uncertain.