Road run-off and associated snow, water recipient and sediment/soil samples were collected in six Nordic countries in spring/summer 2023 and analysed for the presence of 15 tire related chemicals including antioxidants/antiozonants, transformation products and a crosslinking agent. Additionally, 20 blue mussel samples were analysed, summing up to a total of 87 samples. Tire related chemicals were found in 98% of samples, with one compound (TPPD; N-Phenyl-N'-tolyl-p-phenylenediamine) being predominant in all sample matrices. Direct road run-off samples exhibited highest concentrations, while recipient waters were generally less contaminated. A high variability in chemical concentrations and relative abundance of individual compounds was however observed depending on sample type and location. This variability might be driven by the use of different additives in tire formulations, environmental factors (UV irradiation, rainfall) or population density, car use and traffic conditions.
The Nordic countries might be particularly prone to contamination by tire wear and associated chemicals due to a prolonged period in which softer winter tires are used, the use of studded tires and potentially bad road conditions due to harsh climatic conditions. However, while the amount of scientific literature on tire related chemicals is generally increasing, data on the environmental occurrence of TPPD is currently lacking.
The aim of this study was to provide a first assessment of the presence of tire related chemicals in road run-off and associated samples in the Nordic countries. Future studies might monitor the occurrence of these compounds in locations identified as potential hotspots or increase the spatial and/or temporal sampling coverage.