Tire Crumb Questions and Answers
- Which agencies are involved with the Federal Research Action Plan?
- What research is included in the Federal Research Action Plan? Will it answer the question of whether tire crumb rubber is safe?
- What is the status of the research?
- When did the research begin and when will it end?
- Where can I find responses to the public comments on this research submitted through the Federal Register Notices?
- What is the research protocol document?
- Where are the fields located that will be studied?
- How can I find out more information about this research?
- What stakeholder outreach activities have been completed as part of this study?
- What are the key findings of the Literature Review/Gaps Analysis?
- Who regulates the management and disposal of used tires?
- How is tire crumb rubber produced?
- Will the results of the federal research be made public? Will states be given access to help them make decisions about use?
- What are the various markets for tire crumb rubber?
- What is this report and what is it not?
- What are the bottom line results of the tire crumb rubber characterization study? Is there anything communities should be concerned about?
- Why are the results being released in two separate reports? When will the results of the rest of the research effort be released?
- Originally, there was going to be an opportunity for public comment on the draft report, but now it looks like the agencies are releasing a final report without any opportunity for public comment. Why?
- States and other organizations have conducted studies on tire crumb rubber. What have they concluded? How is the Federal Government working with California?
- How is the US Federal Government working with other international government organizations interested in this topic, including the European Chemicals Agency?
- What advice do you have for communities who are concerned about the use of tire crumb rubber in fields?
- Are there any alternative materials/products that can be used?
- How is the federal study similar to and different from other research studies?
- What important data gaps is the federal study filling?
- What is the status of CPSC’s review of playgrounds with tire crumb rubber?
This plan is led and primarily implemented by the US Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention’s Agency for Toxic Substances and Disease Registry (CDC/ATSDR), in cooperation with the US Consumer Product Safety Commission (CPSC) and other agencies. Other agencies such as National Institute of Environmental Health Sciences, the U.S. Department of Defense and California’s Office of Environmental Health Hazard Assessment (OEHHA) are providing expertise, facilities, and/or sharing of information.
Q. What research is included in the Federal Research Action Plan? Will it answer the question of whether tire crumb rubber is safe?
The plan includes four research activities:
- Outreach to key stakeholders - EPA, CDC/ATSDR, and CPSC are having discussions with other government agencies that have researched or are currently researching tire crumb rubber that provide expertise to inform the federal study, and other key stakeholder groups including tire crumb rubber manufacturers, non-profit organizations, field installers and maintenance professionals, and field users.
- Analysis of data gaps - EPA, CDC/ATSDR, and CPSC evaluated the existing scientific information related to the use of tire crumb rubber in synthetic turf fields to understand the current state-of-the-science and inform the research activities. The Literature Review and Data Gaps Analysis is included in the status report released in December 2016.
- Characterization of the chemicals found in tire crumb rubber - EPA and CDC/ATSDR are testing tire crumb rubber from different manufacturing plants and fields. These tests, along with existing scientific information from the literature, will help us better understand the make-up of tire crumb rubber. The Part 1 Report on Tire Crumb Rubber Characterization is now available and can be viewed here.
- Characterization of the exposure scenarios - EPA and CDC/ATSDR are conducting several activities to better understand potential exposures that may occur when people use synthetic turf fields. This work is considering all possible ways that one may be exposed including by breathing, unintentionally ingesting, or touching tire crumb rubber or the chemicals in tire crumb rubber.
Study research activities were prioritized based on data needs and available resources. While this effort won’t provide all the answers related to this topic, the study will provide a better understanding of the chemicals found in tire crumb rubber and the potential exposures that field users may experience by using these fields. This study is not a risk assessment, however, the results of the research described in this and future reports will advance our understanding of exposure to inform the risk assessment process.
The draft report under the Federal Research Action Plan on Recycled Tire Crumb Used on Playing Fields and Playgrounds was sent for external peer-review in May 2018. The Agencies plan to release the report in two parts. The first part summarizing the Tire Crumb Rubber Characterization research is now available and can be viewed here. The second part on Exposure Characterization, which will include information from a biomonitoring study that CDC/ATSDR is currently initiating, will be released at a later date. For more information about the study and timeline, see our website on the Federal Research on Recycled Tire Crumb Used on Playing Fields.
The Federal Research Action Plan (FRAP) launched on February 12, 2016. The data collection components of the tire crumb rubber used in turf fields study received OMB approval in August 2016. Over the period of 10 months between February 2016 and December 2016, EPA, ATSDR, and CPSC engaged various stakeholder groups through several outreach activities including a public comment process, webinars, conference calls, and in-person meetings. The final peer reviewed Literature Review and Data Gaps Analysis report along with a progress report for other components of the study was released in December 2016.
Researchers have evaluated several tire crumb rubber samples taken from fields and manufacturing plants to characterize the chemical make-up of tire crumb rubber. These study results can be found in the part 1 report on Tire Crumb Rubber Characterization, which is now available and can be viewed here.
EPA and CDC are performing research activities that incorporate the tire crumb rubber characterization data into an exposure context. This research involves gathering activity data from people who regularly perform activities on turf fields. CDC/ATSDR is initiating a biomonitoring study to assess exposure among players who play on synthetic turf fields and natural grass fields. These results of these studies activities will be released at a later date.
The Consumer Product Safety Commission’s playground study is still underway. For more information on this part of the FRAP, contact Patty Davis at PDavis@cpsc.gov.
Public comments submitted in response to the 2016 Federal Register Notice have been reviewed by EPA and CDC/ATSDR. EPA and CDC/ATSDR responses to public comments are available online here.
Public comments submitted in response to the 2017 Federal Register Notices have been reviewed by EPA and CDC/ATSDR. EPA and CDC/ATSDR responses to public comments are available online here.
Q. What is the research protocol document?
The research protocol document describes the study design and protocol for research activities in the Federal Research Action Plan including the literature review and data gaps analysis; the tire crumb rubber collection and characterization; and the characterization of human exposure to tire crumb rubber in synthetic turf fields. The document explains the study objectives, research design, methods that are being used to characterize tire crumb rubber and the exposures, data analysis techniques and the quality assurance/quality control measures in place to ensure the integrity of the research.
Tire crumb rubber samples were collected from 40 different playing fields within the four US census regions. These locations include both outdoor and indoor playing fields. Samples were also collected from nine tire crumb rubber manufacturing facilities. To protect privacy, the names of the specific locations sampled will not be released to the public.
As it is available, updated information about the study will be posted to EPA’s Tire Crumb Website.
EPA, ATSDR, and CPSC were engaged various stakeholder groups through several outreach activities including a public comment period, webinars, conference calls, and in-person meetings. Stakeholder outreach efforts were targeted to the public as well as specific stakeholder groups such as government organizations (other federal agencies, state agencies, local government and international government), industry and non-profit/interest groups.
The purpose of the stakeholder outreach was to inform the public about the Federal Research Action Plan on Recycled Tire Crumb Used on Playing Fields and Playgrounds and to encourage stakeholders to provide feedback on studies that are part of the research. The outreach to specific stakeholder groups also included information sharing around the manufacturing and the use of tire crumb rubber in synthetic turf fields.
An important component of any research is to understand the state of the science and any data gaps. The Literature Review and Data Gaps Analysis (LRGA) provides a current summary of the available literature and capture the data gaps as characterized in those publications. The overall goals of the LRGA were to inform the interagency research study and to identify potential areas for future research that might be needed. The LRGA does not include critical reviews of the strengths and weaknesses of each study but does provide the author’s conclusions regarding their research, where applicable. The LRGA also does not make any conclusions or recommendations regarding the safety of the use of tire crumb rubber in synthetic turf fields and playgrounds. The LRGA identified 90 references. Each reference reviewed was categorized according to 20 general information categories (e.g., study topic, geographic location, sample type, conditions, and populations studied) and more than 100 sub-categories (e.g., study topic subcategories: site characterization, production process, leaching, off-gassing, microbial analysis, and human risk). The research in the FRAP addresses many of the gaps identified in the LRGA, particularly with respect to tire crumb rubber characterization and exposure characterization. The review provides information useful for guiding and designing future research efforts needed to further address questions regarding exposures and risks for tire crumb rubber used in synthetic turf fields and playgrounds.
State solid waste agencies are primarily responsible for regulating the management of used tires at their end of life, including options for recycling and disposal. You can consult your state solid waste regulatory agency for information and guidance on the proper management of used tires in a particular state.
Tire crumb rubber is manufactured by reducing scrap tires down to various sizes depending on its intended application and market use, and by removing 99 percent or more of the steel and fabric from them. The tire crumb is classified by sifting screens that return oversize pieces back into the reduction process. Magnets are used throughout the process to remove the wire and other metal contaminants and air separators are used to remove the fabric. The American Society for Testing Materials (ASTM) has a standard test method (ASTM D5644) for determining the particle size distribution of vulcanized particulate rubber (a.k.a. tire crumb rubber). ASTM D5603 classifies vulcanized particulate rubber based on particle size distribution and origin of the rubber.
The agencies will release to the public a final peer-reviewed report describing the findings and conclusions of the studies. As of right now, the first three parts of the research have been completed: Outreach to key stakeholders, Analysis of data gaps, and Characterization of the chemicals found in tire crumb rubber. The final part, Characterization of the exposure scenarios, is still underway.
In the U.S., markets for tire crumb rubber include new rubber products, playground and other sports surfacing, and rubber-modified asphalt. The tire crumb rubber used in these ground rubber applications consumed 1,020,000 tons of scrap tires in 2015, or about 26% of the volume of scrap tires generated. Sports surfaces accounted for 25% of tire crumb rubber use.
Ground Rubber Markets
Molded/Extruded Rubber Products (e.g. rubber gaskets)
Source: Rubber Manufacturers Association: 2015 U.S. Scrap Tire Management Summary.
Tire Crumb Rubber Characterization Research Q&A's
Part 1 provides tire crumb rubber characterization research results that provide greater insight into potential human exposure to chemicals present in the material. Neither Part 1 nor Part 2 of this study, separately or combined, will constitute a human health risk assessment of playing on synthetic turf fields with tire crumb rubber. The results of the research described in the final versions of both Part 1 and Part 2 of this study can inform future risk assessments.
In general, and as expected, our findings support the premise that while chemicals are present in the tire crumb rubber as expected, human exposure may be limited based on what is released into air or simulated biological fluids. Where comparative data are available from this study and previous studies, concentrations of most metal and organic chemicals found in tire crumb rubber were similar. Further, emissions of many organic chemicals into air were found to be below detection limits or test chamber background and releases of metals into simulated biological fluids were very low when compared to the typical assumption of 100% bioaccessibility. All tire crumb rubber samples tested positive for bacteria. This is not surprising, as bacteria are present in soil and on surfaces in our environment.
A webinar was held on August 6, 2019, that provided an overview of the tire crumb rubber FRAP Part I characterization study, the slides and Q&A can be viewed here.
In 2016 the Obama Administration, in response to ongoing questions about tire crumb rubber used on synthetic turf fields asked EPA, CDC/ATSDR and CPSC to conduct a study.
In 2016, the EPA recognized that without exposure there is no risk and, in an attempt to develop a timely response to ongoing concerns identified gaps in its knowledge about the potential exposures to the chemicals contained in tire crumb rubber. After consultation with the Obama Administration, EPA, ATSDR, and CPSC launched this coordinated federal effort to fill important data gaps particularly with respect to understanding potential exposures to chemicals in tire crumb rubber. This research will inform future risks assessments.
The goal of the Federal Research Action Plan on Recycled Tire Crumb Used on Playing Fields and Playgrounds (FRAP) is to characterize potential human exposures to the substances contained in tire crumb rubber. Results of the research effort for synthetic turf fields are being reported in two parts. Part 1 (the document that is being released now), communicates the research objectives, methods, results, and findings for the tire crumb rubber characterization research (i.e., what is in the material). Part 2, to be released at a later date, will attempt to characterize potential human exposures to the chemicals found in the crumb rubber material during use on synthetic turf fields. The Part 2 exposure characterization will include results (not currently available) from a biomonitoring study being conducted by CDC/ATSDR.
Q. Originally, there was going to be an opportunity for public comment on the draft report, but now it looks like the agencies are releasing a final report without any opportunity for public comment. Why?
The report has undergone independent, external peer review in accordance with EPA and CDC policies. A summary of external peer review comments is provided in Appendix V. A response-to-peer review comments document will be released with Part 2. Feedback about the study or report can be sent to RecycledTireCrumb@epa.gov.
The Washington State Department of Health (DOH), in collaboration with the University of Washington School of Public Health conducted a health evaluation, which can be viewed here.
California’s Office of Environmental Health Hazard Assessment (OEHHA), under contract from CalRecycle, is conducting an evaluation of tire crumb rubber. That can be viewed here.
The U.S. National Toxicology Program (NTP), at the request of California’s OEHHA, initiated a research program to conduct short term in vivo and in vitro toxicology studies to enhance understanding of potential health impacts of chemicals released from synthetic turf, with an emphasis on crumb rubber in athletic fields. Those studies can be viewed here.
Several organizations have published important information on this topic since the FRAP literature review and data gaps analysis was completed and published in December 2016. Brief summaries of some of these research efforts and publications have been included in the current Part 1 report.
The European Chemicals Agency (ECHA) contacted EPA expressing their interest in the U.S. study. ECHA is an agency of the European Union that implements chemical legislation for the protection of human health and the environment. This interest has resulted in regular calls with ECHA and an in-person meeting. During these meetings, information related to research efforts are shared. In addition, the Netherlands and France are studying tire crumb rubber and communications with these organizations are on-going. More information about ECHA’s study is available here.
Concerned individuals and community members are encouraged to explore the federal agencies’ websites (CPSC and EPA) to review the research results available to date on the use of tire crumb rubber in playgrounds and synthetic turf fields. In addition, concerned individuals can check their state’s public health agency websites to determine if there are state-specific recommendations. EPA has compiled a list of information sources from state government websites, which can be found here.
Materials that have been used in synthetic turf fields include organic materials like coconut husks or cork. Other synthetic materials have also been used as infill for synthetic turf fields. In addition, CPSC has suggested that the public and homeowners may use shredded mulch, and other materials to create a shock-absorbing surface under backyard and public playgrounds. However, EPA has not independently studied or evaluated any of these alternative materials.
The study shares similarities with ongoing and recent studies like those conducted by Cal-OEHHA, NTP, and RIVM, but also has important differences. Together, these studies provide a range of information that is complementary, while significantly increasing our knowledge about the physical and chemical properties of tire crumb rubber, how people are exposed to these chemicals, and whether there may be health concerns related to the use of tire crumb rubber. For example, NTP is providing some additional information about the chemicals that may be associated with tire crumb rubber, which aligns and compliments with findings gained from the EPA and CDC/ATSDR tire crumb rubber research activities. NTP is additionally examining methods that might be used for toxicity testing and conducting short-term in-vivo and in-vitro toxicity tests.
The federal study is characterizing tire crumb rubber from recycling plants, indoor, and outdoor fields across the United States, while Cal-OEHHA focuses on outdoor fields in California and RIVM studied outdoor fields in the Netherlands. Many of the same metal and organic chemicals are being measured in the studies, with some differences in measured chemicals across the studies that will broaden our understanding of the chemical landscape. Altogether, approximately 175 fields are included across the three studies, improving our understanding about the range and variability of chemicals associated with tire crumb rubber. The federal study includes indoor fields while the other studies do not. All three studies are examining the bioaccessibility of some chemicals.
While multiple studies are applying exposure modeling approaches, the federal study is also assessing the availability and suitability of measurement data and exposure parameter information for exposure modeling.
Previous studies in the United States that assessed chemicals in tire crumb rubber have been based on samples collected only from a few fields and measured only a limited number of chemicals. The federal study is systematically measuring a wide range of physical, chemical, and microbial characteristics, and is assessing the variability of these characteristics across a large number of recycling plants and fields. The study is also measuring important exposure-related characteristics including emissions and bioaccessibility. The federal study will also address important knowledge gaps for synthetic field user exposures that will be included in a later report (Part 2). There is limited information for assessing exposures for both adults and children, particularly for the dermal and ingestion exposure pathways. Biomonitoring data are lacking. The Federal study is assessing the human activity parameters that affect exposures, developing and applying exposure measurement methods for children and adults, applying biomonitoring measurements, and assessing human exposure modeling approaches. The Federal study will help fill important knowledge gaps for tire crumb rubber characterization and provide a better understanding of how people using synthetic turf fields may actually be exposed to chemicals associated with tire crumb rubber.
As part of the Federal Research Action Plan (FRAP), CPSC conducted a playground use survey gathering information about children’s behavior on playgrounds. This survey has been completed and is currently being reviewed by CPSC staff. It could be released as early as fall 2019. CPSC will continue its work on playgrounds by conducting a risk assessment of children’s exposure to playground surfaces made of tire rubber. This work will use the CPSC survey as well as data from EPA’s FRAP Part 1 (characterization of the chemicals and materials in tire rubber crumb), released July 25, and CDC’s (ATSDR) FRAP Part 2 (characterization of potential exposures for those who use turf fields containing tire crumb rubber) after it is released.