California’s Office of Environmental Health Hazard Assessment completed a sweeping, nine-year review and found no evidence of significant health risks from crumb rubber infill made from recycled tires used on synthetic turf fields. The assessment is the most comprehensive state-level look to date and should settle many long-running questions about the material’s safety for athletes and spectators.
The investigation evaluated 35 fields across California, analyzed more than 100 chemicals, and relied on extensive air sampling paired with exposure assessments involving more than 1,000 soccer players. Researchers examined potential exposures for players, coaches, referees and nearby spectators, including young athletes and toddlers, to build a broad picture of real-world use.
Key findings show no meaningful cancer risk linked to crumb rubber exposure under the conditions studied. The report also found no evidence of acute health effects such as sensory irritation, and no indication of reproductive harm or impacts on fetal development among the groups evaluated.
OEHHA Director Kris Thayer summed up the result plainly: ‘This study should ease concerns about the safety of crumb rubber use in synthetic turf fields. Athletes of all ages can use these fields without parents worrying about this commonly used material.’
The final report, released April 28, 2025 after public comments and an advisory panel review, upheld the original conclusions with no major changes. That procedural review and the unchanged findings add weight to the agency’s assessment.
This landmark evaluation addresses a debate that has lingered for years between public health advocates, community groups and the tire recycling industry. For manufacturers and recyclers, it is a timely validation; for school districts and parks departments, it supports continued use of crumb rubber without heightened worry. Tire Review Magazine highlighted the study’s relevance to the tire recycling sector, affirming crumb rubber’s safety profile: https://www.tirereview.com/oehha-crumb-rubber-study/.
The study does not mark the end of scrutiny, but it does change the conversation. With this level of evidence, communities and facility managers can make decisions based on a large, systematic data set rather than uncertainty and speculation.
