This document establishes a general framework and considerations for assessing the environmental fate of tyre tread chemical additives in cured polymer and tyre and road wear particles (TRWP) throughout a tyre lifecycle. This document is applicable to laboratory-generated TRWP from cured tread polymer of known composition.
Testing strategies are described for assessing the environmental fate and transport of tyre chemicals in the following processes that can occur during the tyre lifecycle:
a) transformation of chemical additives in tread during tyre curing;
b) transformation of chemical additives during TRWP generation (tyre use);
c) transformation of chemical additives during TRWP aging and weathering;
d) leaching of chemical additives and transformation products from TRWP to water;
e) availability of chemical additives and transformation products from TRWP in sediment ecosystems.
Mass concentrations and fractions of chemicals released or available from TRWP for the five lifecycle steps are used to estimate
a) cumulative fraction of tread chemical(s) and transformation product(s) released to water, and
b) cumulative fraction tread chemical(s) and transformation products(s) environmentally available.