Q. Which agencies are involved with the research?

This plan is led and chiefly implemented by the US Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention’s National Center for Environmental Health/Agency for Toxic Substances and Disease Registry (CDC-NCEH/ATSDR), in cooperation with our agency. 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 will provide expertise, facilities and/or sharing of information.


Q. What research is included in the Federal Research Action Plan?

The plan includes four research activities:

  1. Conduct a data gaps analysis - EPA, CDC/ATSDR, and CPSC are evaluating the existing scientific information related to recycled rubber tire crumb used in artificial turf fields and on playgrounds to build on the current understanding of the state-of-the-science and inform the research activities.
  2. Characterize and test tire crumb materials - EPA, CDC/ATSDR, and CPSC are testing different types of tire crumb from manufacturing plants and from fields. These tests, along with existing scientific information from the literature, will help us better understand the make-up of tire crumb materials.
  3. Develop exposure scenarios - EPA, CDC/ATSDR, and CPSC are conducting several activities to better understand potential exposures that may occur when people use artificial turf fields and playgrounds. This work is considering all possible ways that one may be exposed including by breathing, unintentionally ingesting, or touching tire crumb or the chemicals in tire crumb. CPSC’s playground studies include gathering information about children’s behaviors on playgrounds that could promote exposure to recycled tire rubber and its chemical constituents.
  4. Outreach to key stakeholders, states, relevant federal agencies and others - EPA, CDC/ATSDR, and CPSC are having discussions with other agencies that have researched tire crumb or have research underway; agencies that can provide expertise to inform the federal study; and are having discussions with key groups including tire crumb manufactures, field installers, and field users.

While this effort may not address all of the public’s questions, the information will help answer some of the key questions that have been raised about tire crumb used in artificial turf fields and playgrounds and will provide a better understanding of potential exposures that users may experience. Depending on the findings, available resources and other considerations, additional research beyond the first year is likely to be needed. It is also important to note that the research is being conducted within an ambitious timeframe.


Q. What is the status of the research?

Researchers at EPA are currently evaluating the samples to characterize the chemical make-up of tire crumbs. An additional study activity will gather activity data from people who regularly perform activities on turf fields. Collection of tire crumb samples from fields and recycling facilities is complete. Tire crumb samples were gathered from nine tire crumb recycling plants, 19 fields located on US Army installations and 21 community fields across the U.S. The analysis of the samples is currently underway. Fields included both outdoor and indoor fields. To protect privacy, the specific locations of the fields being sampled cannot be released.

EPA, ATSDR, and CPSC have engaged various stakeholder groups through a number of outreach activities including webinars, conference calls, in-person meetings, and a public comment process. 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 Synthetic Turf Fields with Tire Crumb Rubber Infill Research Protocol document which is providing guidance for the studies has been extensively reviewed, including an external peer-review and an Institutional Review Board review, and the document is now final. One of the main research activities is gathering tire crumb samples from tire crumb manufacturing plants and from fields across the country. The data collection for the tire crumb samples and analysis went through a public comment period and an Information Collection Request review conducted by the Office of Management and Budget. Peer-review and public comments are publicly available on the OMB’s website.

CPSC is using a combination of field observations, focus groups, and a national survey of parents and child care providers to collect information on children’s behaviors on playgrounds and identify exposure factors. CPSC staff used information gathered by the field observations and focus groups to develop a national survey of parents and caregivers which is currently under OMB review. Findings of the national survey will be used to inform development of exposure scenarios and exposure factors which can be used to estimate children’s exposure to substances of concern in playground surfaces made with recycles tires. 

As it is available, updated information will be posted to EPA’s tire crumb website (www.epa.gov/tirecrumb). When the EPA and ATSDR studies are completed, the agencies intend to release a final peer-reviewed report describing the findings and conclusions of two study activities--the characterization of the chemicals and materials found in tire crumbs and the characterization of the exposure scenarios for those who use turf fields containing tire crumbs. The report will also outline any additional research needs and next steps. Our agency’s playground study will continue.

Q. What advice do you have for communities who are concerned about playgrounds with recycled tire surfaces?

We recognize that communities, parents and state and local officials are concerned about recycled tire materials used in playground surfacing. The study’s findings will provide a better understanding of potential exposures children may experience by using playgrounds with recycled tire surfacing. While this short-term study won’t provide all the answers, the information will help answer some of the key questions that have been raised.

Communities, parents, state and local officials are encouraged to explore Federal Agency websites (CPSC - https://www.cpsc.gov/Safety-Education/Safety-Education-Centers/Crumb-Rubber-Safety-Information-Center and EPA - www.epa.gov/tirecrumbs) to review the research results available to date on the use of recycled rubber tires for playgrounds and artificial turf fields. In addition, concerned individuals can check their state’s public health agency websites to determine if there are state-specific recommendations.

While no specific chemical hazards from recycled tires in playground surfacing are known by the CPSC at this time, the following precautions to limit exposure are recommended:

  1. Avoid mouth contact with playground surfacing materials, including mouthing, chewing, or swallowing playground rubber. This may pose a choking hazard, regardless of chemical exposure.
  2. Avoid eating food or drinking beverages while directly on playground surfaces, and wash hands before handling food.
  3. Limit the time at a playground on extremely hot days.
  4. Clean hands and other areas of exposed skin after visiting the playground, and consider changing clothes if evidence of tire materials (e.g., black marks or dust) is visible on fabrics.
  5. Clean any toys that were used on a playground after the visit.

Q. Are there any alternative materials/products that can be used?

EPA is aware of a few alternatives to tire crumb that can be used as infill in artificial turf, such as the use of organic materials like sand, coconut husks, or cork. In addition, CPSC has suggested that the public and homeowners may use shredded wood mulch, and other materials to create a shock-absorbing surface under backyard and public playgrounds.  

Q. When will the research begin and when will it end?

The Federal Research Action Plan was released on February 12, 2016. The data collection components of the tire crumbs used in turf fields study received OMB approval in August 2016. The final peer reviewed Literature Review and Data Gaps analysis report along with a progress report for other components of the study is being released as part of this report. The agencies intend to release a final peer-reviewed report describing the findings and conclusions of two tire crumb studies–the characterization of the chemicals and materials found in tire crumbs, and the characterization of the exposure scenarios for those who use turf fields containing tire crumbs. The peer-review report will also outline any additional research needs and next steps.  It is also important to note that the research is being conducted within an ambitious timeframe and has limited resources. The Consumer Product Safety Commission’s playground study has a longer timeline.


Q. How can I get involved and find out more information about this research?


As it is available, updated information about the study will be posted on our agency’s Crumb Rubber Information Center

Q. What stakeholder outreach activities have been completed as part of this study?

EPA, ATSDR, and CPSC have engaged various stakeholder groups through a number of outreach activities including webinars, conference calls, in-person meetings, and a public comment process. 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.


Q. What are the various markets for crumb rubber?

In the U.S., markets for crumb rubber include new rubber products, playground and other sports surfacing, and rubber-modified asphalt.  The crumb rubber used in these ground rubber applications consumed 975,000 tons of scrap tires in 2013, or about 25% of the volume of scrap tires generated. Approximately 31% of the ground rubber market was used for the combination of playground, mulch, and animal bedding purposes (a more precise percentage used for only playgrounds were not available). Sports surfaces accounted for 17% of crumb rubber use. 

Ground Rubber Markets

 

Molded/Extruded Rubber Products (e.g. rubber gaskets)

33%

Playground/Mulch/Animal Bedding

31%

Sports Surfaces

17%

Asphalt

7%

Automotive

6%

Export

6%

Source: Rubber Manufacturers Association:  2013 U.S. Scrap Tire Management Summary  


Q. What types of playground surfaces are included in the CPSC’s studies?

Playground surfaces can be divided into two main categories: loose-fill systems and unitary systems. A loose-fill system consists of small, independent, moveable components, such as sand, gravel, wood chips, engineered wood fiber, rubber particles, and similar materials. A unitary system consists of one or more components bound together, such as foam composites, urethane/rubber systems, like prefabricated blocks, tiles, or mats, or as poured-in-place and similar materials. Our agency’s Public Playground Safety Handbook describes that appropriate playground surfacing should be designed and tested to comply with ASTM F1292-13, Standard Specification for Impact Attenuation of Surfacing Materials Within the Use Zone of Playground Equipment.

CPSC staff identified five general types of playground surfaces that are made with recycled tire materials:

  1. Loose-Fill Rubber is a loose-fill system consisting of rubber nuggets or buffings and is sometimes described as rubber mulch. The nuggets or buffings are typically created from recycled tires. Rubber mulch intended or marketed for landscaping or gardening uses may not be appropriate for use as a playground surfacing; consumers should verify on the packaging or product label that it is safe for use on playgrounds. The Public Playground Safety Handbook notes that loose-fill systems should be avoided for playgrounds intended for toddlers
  2. Rubber Tiles provide a unitary system consisting of factory-formed tiles, mats, or pavers made of an energy-absorbing material, such as recycled tire rubber. Rubber pieces of varying sizes are formed into solid design shapes with pressure and heat and/or a binder such as polyurethane.
  3. Poured-in-Place (PIP) describes a unitary system that consists of a combination of rubber crumb, chips, or buffings, or all three, with a polymer binder in specific percentages determined by the manufacturer/installer that is mixed proximate to the playground and poured in one or more layers on a prepared base to provide a smooth and seamless surface. The poured-in-place surface is generally installed in two layers, with the lower layer being a cushioning layer and the top being a wear-coarse layer. The wear-coarse layer may be colored for cosmetic effect and provides a durable contact surface to protect the cushioning rubber crumb layer from wear and erosion. ASTM standard F2479-12 describes the standards for specification, installation, and maintenance of PIP surfacing.
  4. Bonded Rubber describes a type of PIP system that is typically made with a single layer of buffing-size rubber particles mixed with a polymer binder and less densely applied than the two-layer PIP systems described above. Bonded rubber is porous, allowing water to flow through it.
  5. Synthetic Turf is an engineered artificial grass product that gives a playground surface the appearance of natural grass but offers impact attenuation protection. Less information is available on synthetic turf as a playground surface type than for the loose-fill and PIP surfaces. Synthetic turf used on playgrounds appears to differ from the synthetic turf used on athletic fields and consists of an artificial grass “carpet” installed over a PIP unitary system (buffing or crumb-size rubber) or a layer of porous closed-cell composite or other cushioning material. CPSC staff was unable to find any installers that use recycled tire crumb as an infill as it is used in athletic fields. Sand with or without a polymer coating appears to be the most common infill material used on playground turf. The Public Playground Safety Handbook does not address synthetic or artificial turf as a playground surfacing material. The published ASTM standards for synthetic turf appear to be specific to turf used on athletic fields and not playgrounds

Other non-rubber surfacing types commonly found on playgrounds include loose-fill wood products (e.g., mulch, chips, and engineered wood fiber), sand, and pea gravel. These non-rubber options are not addressed in the Federal Research Action Plan. Additionally, the current studies do not include the use of playground equipment (e.g., tire swings or climbing structures) made from whole or partial tires.


Q. How are tire crumb and tire mulch produced?

Tire crumb 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 standards for specifying different size ranges for tire crumb applications. ASTM D5603 Standard Classification for Rubber Compounding Materials-Recycled Vulcanizate Particulate and ASTM D5644 Test Methods for Rubber Compounding materials-Determination of Particle Size Distribution of Recycled Vulcanizate Particle Rubber.


Q. States and other organizations have done studies on tire crumb. What have they concluded?

Current information from a number of studies does not show an elevated health risk from playing on fields with tire crumb. However, these studies do not comprehensively address the concerns about the potential health risks associated with exposure to tire crumb.


Q. Will the results of all of this research be made public?  Will states be given access to help them make decisions about use?

The agencies intend to release a final peer-reviewed report describing the findings and conclusions of two tire crumb studies including characterization of the chemicals and materials found in tire crumbs used in artificial turf fields and the characterization of the exposure scenarios for those who use turf fields containing tire crumbs. The peer-review report will also outline any additional research needs and next steps.


Q. Who regulates the management and disposal of used tires and defines a product as a solid waste?

State and local governments are the primary agencies for regulating the management of used tires and have been responsible for assessing the environmental and public health impacts and challenges of managing tire piles, which can be vectors for mosquitoes and/or at risk for tire fires. Concerned individuals can check their state’s public health agency websites to determine if there are state-specific recommendations for what to do if children and others come in contact with tire crumbs.