California’s environmental safety agency has concluded that recycled tyres used as crumb rubber in synthetic turf are unlikely to cause cancer or other health problems for those who play on these pitches. This follows years of lingering debate about the safety of such artificial turf.
‘Considering the health-protective, “worst-case” assumptions and parameters used in the exposure assessment, the small exceedances in the few instances and scenarios associated with turf field-related chemicals are of low probability and of low concern, and would not require further evaluation,’ stated the report of California’s Office of Environmental Hazard Assessment (OEHHA), released on 5 March.
To reach its conclusion, the OEHHA investigated 35 synthetic turf fields across California by collecting data on their individual environmental conditions and conducting ‘non-targeted analyses’ to identify the different kinds of chemicals that are present in crumb rubber. The study also measured the potential exposure of the synthetic turf field users to these chemicals, conducted ‘time-activity’ studies to obtain data on their typical contact with the crumb rubber, and refined models previously used to assess potential exposure and health risks.
In addition, OEHHA developed a model to describe scenarios of human exposure to chemicals released from crumb rubber infill of synthetic turf fields. It illustrates, among other things, how gases from synthetic turf are released into the air and breathed in by athletes, coaches, as well as spectators.
So-called ‘third generation’ playing surfaces for sports consist of artificial grass, a layer of sand and rubber granules spread between the synthetic grass fibres. Controversy has dogged this synthetic turf for several years, however. In 2017, for example, an analysis by the Dutch National Institute for Public Health and Environment found the health risks from rubber granules on sports pitches to be negligible. But another study led by researchers at the University of Amsterdam appeared to dispute this conclusion, reporting that these rubber granules in fact release chemicals that could cause harm.
Despite anecdotes about ill health caused by these surfaces, there was little research until recently.
‘This study should ease concerns about the safety of crumb rubber use in synthetic turf fields,’ stated OEHHA’s director, Kris Thayer. ‘Athletes of all ages can use these fields without parents worrying about this commonly used material.’
But some public health experts, such as Andrew Watterson, an occupational and environmental health researcher at the University of Stirling who has researched artificial turf, are sceptical about the conclusions reached. ‘The big picture should be used to assess the material – a holistic not reductionist approach – and that would conclude a precautionary policy should be used and crumb rubber phased out from 3G pitches,’ Watterson tells Chemistry World.
‘A number of European researchers have questioned the approach and information in the OEHHA interim report and some of us have similar reservations about the final report,’ Watterson states. ‘The report has much useful detail, and the information will be valuable, but it claims far too much for modelling studies when personal and biomonitoring studies were not conducted and there are big gaps in the numbers of chemicals assessed.’ In addition, he says there is a lack of ‘good, well-conducted epidemiology studies’ of users of 3G pitches.
Hans Larsson at McGill University in Canada, who has researched the toxicological effects of the materials used to create synthetic turf, is also concerned. ‘I would rather not get into a debate about the toxicity of crumb rubber at this level,’ he says, ‘but I would question what “available data” they reference, or what data was not made available to them.’
Moreover, Larsson says he was ‘surprised to hear this from California’, given the EU and even some jurisdictions in the US have banned artificial turf. California is widely considered one of the most aggressive states when it comes to environmental regulation, and it often sets standards that are that are significantly more rigorous than federal laws.
An earlier report, released by the US Environmental Protection Agency and other federal agencies in April 2024, mirrored some of OEHHA’s conclusions, finding that the crumb rubber in artificial turf contains dangerous chemicals but that human exposure to them appears to be too low to cause significant health risks.
Meanwhile, in October 2023 the EU moved to ban the sale of tyre crumb rubber infill for use on synthetic sports surfaces under its Reach chemicals regulation, and this prohibition goes into effect in October 2031. But rather than being based on human health concerns, that action was based primarily on the concern that such crumb rubber is a major source of microplastics entering the environment.
No comments yet