A systematic literature review of research on end-of-life tyres has found that chemicals leaching out of products made from waste tyres can be harmful to aquatic organisms.
These findings are particularly significant, as Australia generated more than 500,000 tonnes of used tyres in 2023–24. Around a quarter of these tyres were recycled or reused in products such as playground surfaces, roads and artificial turf.
The literature review is a synthesis document authored by researchers Dr Peta Neale and Professor Frederic Leusch, both from Griffith University, and Dr Glen Walker, Principal Regulatory Scientist and Director from the Australian Government's Department of Climate Change, Energy, the Environment and Water. The review examined 99 international peer reviewed studies between 1993 to 2026.
Together, these studies tested leachate from waste tyre products and tyre particles on 41 and 32 species, respectively, including fish, crustaceans and algae.
The water flea Ceriodaphnia dubia was among the most sensitive species tested to leachate from crumbed rubber.
Zinc was often identified as a main cause of toxicity. Other chemicals linked to effects included benzothiazole, aniline and 6PPD-quinone, a transformation product of a tyre antioxidant.
The researchers found that tyre particles could be more harmful than leachate alone, as organisms may be affected by both the chemicals released and the particles themselves.
But comparisons between studies remain difficult: different leaching conditions can change which chemicals are in the leachate and in what amounts.
The review also found too little evidence to compare cell-based tests with conventional tests on whole organisms.
The authors note the importance of future research that tests leachates from waste tyre products under consistent conditions, combining both kinds of tests with chemical analysis – which forms the next phase of this project.
The review is part of a wider project led by Leusch, with Neale and Associate Professor Will Bennett, testing whether effect-based methods can help assess the environmental risks of chemicals released from products made from end-of-life tyres.
The team is also developing a framework for assessing potential hazards and compiling chemical and toxicity data in a reusable electronic format that will make the information more useful for other researchers and regulators.
The work aims to help regulators and policy makers determine whether leachates from waste tyre products could harm the environment, and how risks can be assessed quickly and without the need for testing on animals.
Read the Report: Ecotoxicity of tyre wastes: A systematic literature review
