Biomonitoring Study of Polycyclic Aromatic Hydrocarbon Exposure Among Users of Synthetic Turf Fields Containing Tire Crumb Rubber Infill

Background: In 2022, ATSDR conducted a biomonitoring study to supplement the pilot exposure measurement activities conducted as part of the U.S. Federal Research Action Plan on Recycled Tire Crumb Rubber Used on Playing Fields and Playgrounds. Methods: Participant recruitment took place across three athletic facilities, including two outdoor facilities and one indoor facility. The outdoor facilities featured synthetic turf fields with recycled tire crumb rubber infill co-located with natural grass fields. Seven polyaromatic hydrocarbon (PAH) metabolites were quantified from pre- and post-activity urine samples and adjusted for specific gravity and creatinine. Univariate and multivariate models of Ln-transformed concentrations were examined for statistical associations with field type (i.e., synthetic turf or natural grass) and field environment (i.e., indoor or outdoor). Results: Of 161 study participants (age range: 7-77 years), 132 (82%) used synthetic turf with tire crumb rubber infill and 29 (18%) used natural grass fields. Among synthetic turf users, 41 (31%) participants were sampled while playing indoors and 91 (69%) were sampled while playing outdoors. Overall, synthetic turf users and natural grass field users experienced similar differences in pre- and post-activity PAH concentrations. Differences in pre- and post-activity PAH concentrations did not statistically significantly differ by indoor and outdoor synthetic turf fields. Conclusions: In the current study, no significant differences were observed in pre-and post-activity PAH concentrations based on field type or field environment. The biomonitoring study contributes to our understanding of the potential for exposure to chemicals found in recycled tire crumb rubber. Disclaimer: The findings and conclusions in this presentation are those of the author(s) and do not necessarily represent the views of EPA and/or CDC/ATSDR.

Impact/Purpose

In the United States, synthetic turf fields are used at municipal and county parks; schools, colleges, and universities; professional sports stadiums and practice fields; and military installations and are designed to simulate the experience of practicing and playing on grass fields. First introduced in the 1960s, synthetic turf fields have evolved over time from first-generation systems made of tightly curled nylon fibers to third-generation systems typically made of polyethylene yarn fibers. These third-generation systems typically use small pieces of recycled tires, referred to as "recycled tire crumb rubber" (or simply "tire crumb rubber"), to fill the space between the polyethylene yarn fibers. The recycled tire crumb rubber (sometimes mixed with sand or other raw materials) is added for ballast, support for the synthetic grass blades, and as cushioning for field users. Third-generation synthetic turf field systems are widely used today. There are between 18,000 and 19,000 synthetic turf fields in the United States, with 1,200 – 1,500 new installations each year, and about half of those are replacements.[2] It is estimated that millions of people use and/or work at these fields. Some parents, athletes, schools and communities have raised concerns about the use of recycled tire crumb rubber on synthetic turf fields. To help address these concerns, the Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry (CDC/ATSDR) and the U.S. Environmental Protection Agency (EPA), in collaboration with the Consumer Product Safety Commission (CPSC), launched a multi-agency research effort in February 2016. This multi-agency research effort, known as the Federal Research Action Plan on Recycled Tire Crumb Used on Playing Fields and Playgrounds (FRAP), is focused on assessing potential human exposure, which includes conducting research activities to characterize the chemicals associated with recycled tire crumb rubber and to identify the ways in which people may be exposed to those chemicals based on their activities on synthetic turf fields. Also, the FRAP includes characterizing emissions and bioaccessibility to differentiate what is present in the recycled tire crumb rubber from what people may actually be exposed to from recycled tire crumb rubber. It is important to note that the study activities completed as part of this multi-agency research effort were not designed, and are not sufficient by themselves, to directly answer questions about potential health risks. Other studies may aid in this regard. Overall, we anticipate that the results from this multi-agency research effort will be useful to the public and interested stakeholders for understanding the potential for human exposure to chemicals associated with recycled tire crumb rubber infill material used on synthetic turf fields.

Citation

Thomas, K., T. Wang, M. Lewin, A. Ragin-Wilson, AND E. Irvin. Biomonitoring Study of Polycyclic Aromatic Hydrocarbon Exposure Among Users of Synthetic Turf Fields Containing Tire Crumb Rubber Infill. ISES 2024 Meeting, Montreal, CANADA, October 20 - 24, 2024.