Landmark Study Finds No Significant Risk from Key Component of Synthetic Turf Fields

SACRAMENTO – The California Office of Environmental Health Hazard Assessment (OEHHA) released a study finding that recycled tires used as crumb rubber in synthetic turf are not likely to harm users or spectators. There is no evidence of significant risk for cancer or other health problems from this recycled rubber to players, coaches, referees and spectators based on the available data, even for young athletes. 

"This study should ease concerns about the safety of crumb rubber use in synthetic turf fields," said OEHHA Director Kris Thayer, "Athletes of all ages can use these fields without parents worrying about this commonly used material."

Synthetic turf fields are engineered to resemble natural grass but require less maintenance, use less water, and provide consistent playability without rest periods. These properties have led to widespread use on athletic fields, including more than 900 installations in California. 

Many fields use crumb rubber, small granules produced by grinding up recycled waste tires, as infill material placed between the synthetic grass blades. This infill helps keep the blades upright, provides cushioning, and improves traction during play. 

Informing California’s circular economy 

OEHHA studied this material to inform California’s sustainability goals. California’s Waste Tire Program sets standards for safely managing waste tires and explores appropriate markets for materials that might otherwise be landfilled. "Protecting public health is our top priority, and California is committed to making sure waste tires are managed safely so they don’t litter communities or pose risks to residents," CalRecycle Director Zoe Heller said. "CalRecycle appreciates the work of OEHHA and its partners to advance our understanding in support of a cleaner, healthier circular economy."

Comprehensive study design

To evaluate safety, OEHHA tested 35 synthetic turf fields. The sampling accounted for both old and new fields, as well as fields from every climate region in California. Multiple samples from each field were collected to account for variations in source materials. OEHHA also collected air samples both during active use of the field and when no use occurred. OEHHA’s groundbreaking study focused on more than 100 chemicals that could pose a risk — unlike past studies that only looked at a small number of chemicals. To identify the full suite of chemicals present, OEHHA coordinated with the Lawrence Berkeley National Lab to simulate sweat and digestion and identify chemicals to which the public could be exposed. 

To understand how people might be exposed to chemicals found, OEHHA worked with researchers from UC Berkeley and the University of Arizona. They studied how soccer players might contact crumb rubber—through skin, breathing, or swallowing small pieces. The team surveyed more than 1,000 soccer players, ages 7 to 71, about how they play, like sliding or diving on the field. They also recorded players during games and practices to see how often they touched the turf. Because goalies dive the most, the study used goalie data to estimate risk for players. Researchers also looked at chemical risk to toddlers who might crawl on the field. 

No significant risk found

OEHHA found no acute risk to athletes, referees, coaches, or spectators, including toddlers. In most cases, risk of sensory irritation, cancer, harm to the reproductive system or a developing fetus, or other health effects were negligible.

About the Office of Environmental Health Hazard Assessment 

The California Office of Environmental Health Hazard Assessment (OEHHA) is the lead state agency for the assessment of health risks posed by environmental contaminants. OEHHA’s mission is to protect and enhance the health of Californians and our state’s environment through scientific evaluations that inform, support and guide regulatory and other actions. As the California Environmental Protection Agency’s (CalEPA) scientific adviser, OEHHA works within CalEPA and across state government, with other state and federal agencies, businesses, community-based organizations, and Native American Tribes across California to develop actionable science that protects public health.

In addition to assessing health risks posed by chemicals, OEHHA develops data tools that support environmental health, performs outreach and education about pesticides and other chemicals, surveys exposure to harmful chemicals through Biomonitoring California, and assists in emergency response through expert consultation on matters related to chemical exposures.