Deep dive into the chronic toxicity of tyre particle mixtures and their leachates

Particles from the tread of vehicle tyres are a global pollutant, which are emitted into the environment at an approximate rate of 1.4 kg.year-1 for an average passenger-car. In this study, popular tyre brands were used to generate a tyre tread microparticle mixture. The chronic toxicity of both particles and chemical leachates were compared on a planktonic test species (Daphnia magna). Over 21 days of exposure, pristine tyre tread microparticles were more toxic (LC50 60 mg.L-1) than chemical lechates alone (LC50 542 mg.L-1). Microparticles and leachates showed distinct effects on reproduction and morphological development at environmentally relevant concentrations, with dose-dependent uptake of particles visible in the digestive tract. Chemical characterization of leachates revealed a metal predominance of zinc, titanium, and strontium. Of the numerous organic chemicals present, at least 54 were shared across all 5 tyre brands, with many classified to be very toxic. Our results provide a critically needed information on the toxicity of tyre tread particles and the associated chemicals that leach from them to inform future mitigation measures. We conclude that tyre particles are hazardous pollutants of particular concern that are close to or possibly above chronic environmental safety limits in some locations.

Tyre granulate on the loose; How much escapes the turf? A systematic literature review

Tyre granulate used as infill for artificial turf is hailed by some as a good example of reuse, while others see it as a baleful means to dispose of discarded tyres. Because the particles are applied loosely to the surface, they will inevitably disperse into the environment. The possible environmental and health impacts of the particles are a source of societal concern. In response to this, policies to limit particle losses are being developed at the European level. To make informed decisions, data on the quantity of tyre granulate released into the environment are required. So far, however, there are no systematic reviews on or estimates of these losses. The aim of the present study was to identify the various pathways through which infill leaves a football turf and, subsequently, to estimate the quantity of infill leaving the turf by each of these pathways. Data on the pathways including the associated volumes were collected in a systematic literature review following the PRISMA method. The quality of the evidence reported in the retrieved literature was assessed using the GRADE method. The resulting pathways and corresponding quantities were captured in a mass balance. This study estimates that, without mitigation measures, approximately 950 kg/year (min. 570 kg/year, max. 2280 kg/year) of infill leaves the surface of an average artificial football turf via known pathways. Clearing snow can result in an additional loss of 830 kg/year (min. 200 kg/year, max. 2760 kg/year) of infill material. To mitigate the dispersion of infill, one could focus on snow removal, brushing and granulate picked up by players. Mitigation measures for these pathways are well-established and relatively easy to implement and maintain. Although the amount of granulate picked up from the turf by players is relatively small, the measure will promote environmental awareness among the players.

Microplastic pollution in a stormwater floating treatment wetland: Detection of tyre particles in sediment

Synthetic rubber particles released from car tyres are expected to be an important type of microplastics in the environment, with road runoff and stormwater likely to transport tyre particles to the aquatic environment. Stormwater treatment wetlands are one of the key methods for treating road runoff and stormwater, but the presence and concentration of synthetic rubber microplastics from tyre particles in wetlands are largely unknown. In addition, constructed floating wetlands can be built using recycled PET plastic bottles, raising concerns about potential release of microplastics to the environment. In this study, we measured the concentrations of microplastics in water and sediment from the inlet and outlet of a stormwater floating treatment wetland on Queensland's Gold Coast. An average of 0.9 ± 0.3 and 4.0 ± 2.4 microplastic particles/L were detected in the water phase in the inlet and outlet samples, respectively. The sediment contained an average of 595 ± 120 and 320 ± 42 microplastic particles/kg dry sediment in inlet and outlet sediments, respectively. Between 15 and 38% of microplastics in the sediment were identified by FTIR as synthetic rubber-carbon filled particles, most likely derived from car tyres. The presence of synthetic rubber microplastics confirms that tyres can contribute to microplastic pollution in stormwater, with road runoff likely to be an important pathway. No microplastics with the same characteristics and polymer composition as the floating wetland construction material were detected in the water and sediment samples, indicating that the microplastics in the water and sediment detected here did not originate from the floating wetland's material. However, further investigation of older treatment wetlands is required to better understand the potential role of floating treatment wetlands as a source of microplastics.