EPA: Federal Research on Recycled Tire Crumb Used on Playing Fields and Playgrounds

Synthetic Turf Field Recycled Tire Crumb Rubber Characterization Research Final Report: Part 2 -Tire Crumb Exposure Characterization now available. Access and download the report.

EPA and CDC/ATSDR reported research findings in two parts. Part 1, which was released in 2019, communicated the research objectives, methods, results and findings for the tire crumb rubber characterization research (i.e., what is in the material). Part 2, which was released in April 2024, includes data to characterize potential human exposures to the chemicals found in the tire crumb rubber material while using synthetic turf fields. Part 2 was released along with results from a biomonitoring study conducted by CDC/ATSDR to investigate potential exposure to constituents in tire crumb rubber. CPSC is conducting separate research on playgrounds. Learn more through the Tire Crumb Rubber Questions and Answers.

The Tire Crumb Rubber Characterization (Part 1) Report outlined that, as expected, a range of metals, semivolatile organic compounds, volatile organic compounds and bacteria were detected in recycled tire crumb rubber infill. Bioaccessibility of metals in tire crumb, related to ingestion or dermal exposure, and emissions of organic chemicals from tire crumb rubber were also measured.

EPA and ATSDR also completed a pilot-scale exposure study including collection of both indoor and outdoor field, personal, and biomarker samples for indicators of exposures; questionnaire and video-based activity assessments; and exposure modeling assessments. Following ATSDR’s completion of a supplemental biomonitoring study, EPA and ATSDR finalized and released the Tire Crumb Exposure Characterization (Part 2) in April 2024, which completes the EPA/ATSDR work with respect to playing fields.

For the work outlined in Part 2, potential exposures were determined using personal samples (skin wipe samples taken from study participants). These samples were analyzed for SVOCs and metals. Air, dust, and surface samples were also taken at the fields. All samples were analyzed for SVOCs and metals. In addition, air samples were analyzed for VOCs and total suspended particulate matter. The study participants’ biomarker samples (urine, blood, and serum) were analyzed for metals and polycyclic aromatic hydrocarbons metabolites.

A range of chemicals was found in skin wipe samples, and in air, field surface, field dust, including metals and organic chemicals. For example, for many chemicals detected during active play at the outdoor fields, concentrations in air were not different than background samples, while others, such as methyl isobutyl ketone, benzothiazole, 4-tertbutyl phenol, and several PAHs, were somewhat higher. Many chemicals were found at higher concentrations in air samples at the indoor field compared to the outdoor fields.

In general, the findings from the entire playing fields field portion of the FRAP study (both the Tire Crumb Characterization Part 1 and the Tire Crumb Exposure Characterization Part 2 combined) support the conclusion that although chemicals are present (as expected) in the tire crumb rubber and exposures can occur, they are likely limited, for example:

• Generally, only small amounts of most organic chemicals are released from tire crumb into the air through emissions. For many chemicals measured during active play at the outdoor fields, concentrations in air were not different than background samples while others were somewhat higher.
• For metals, only small fractions (i.e., <1 to 3%) are released from tire crumb rubber into simulated biological fluids compared to a default assumption of 100% bioaccessibility.
• In the biomonitoring pilot study, concentrations for metals measured in blood were similar to those in the general population.
• No differences in PAH metabolites in urine were observed between study participants using synthetic turf fields compared to those using grass fields.

Study Documents