Nyedra W. Booker PharmD MPH and Stephanie Fox-Rawlings PhD, National Center for Health Research
Is your child playing on rubber instead of grass at the playground? The use of human-made surfaces on playgrounds has increased dramatically over the years. First developed in 1964, the first artificial turf was marketed as “Chemgrass” by Monsanto, and renamed Astroturf more than 2 years later when it was installed at the Houston Astro’s Astrodome.1 In addition to artificial grass, these artificial surfaces have expanded and many look like colorful rubber surfaces. But regardless of what they look like, all are made with materials that can be dangerous to children and adults.
As its use for various sports activities increased significantly over the years, so did the concerns. Athletes began to complain that the surface was much harder than natural grass, as some studies also began to show that the use of artificial turf could increase the risk for football and other sports-related injuries. This prompted a ban on the use of artificial turf by the English Football Association in 1988, and many ballparks and professional sports stadiums in the United States began converting back to using natural grass during the 1990s. Over time, material such as rubber was added to keep the blades of “grass” in place and provide more cushioning.1 Artificial turf containing rubber and other cushioning materials was also assumed to reduce sports-related injuries, but study results have not always supported that assumption.2 Even with modern fields, many professional athletes dislike playing on artificial turf. It increases the severity of abrasions due to sliding, puts additional stress on joints, and heats up much more than grass does in the sun – and can become dangerously hot.3,4 Following their failure to force soccer’s international governing body (FIFA) to use sod instead of artificial turf for the 2015 Women’s World Cup, an international group of women players sued FIFA, although they ultimately dropped the law suit when FIFA refused to budge.5
Artificial turf is marketed as a long-lasting “all-weather” material that does not require a lot of maintenance in the short-term. Artificial turf is currently used on more than 12,000 athletic fields in the U.S.6 The fields cost approximately half a million dollars and are usually under warranty for 8 years.
From the Tire Swings to Play Surfaces made from Tires or New Rubber
Do you remember when children used to play on tire swings in the backyard or at the park? Those same tires are now being put to a new and possibly hazardous use! Recycled rubber tires have become one of the top choice materials for surfacing children’s playgrounds.7 In 2019, approximately 290 million tires were discarded,6 of which approximately 12% were processed for sports fields and playground surfaces.8 Logically, tire scraps seemed like a surface that would be less likely to harm children if they fell. Recycling tires for use in playgrounds also keeps them out of landfills where they take up space, harbor rodents and other animals, and trap standing water that serve as breeding grounds for mosquitoes and other disease-bearing insects. However, the tire crumb from artificial turf washes away into nearby grass and waterways, and when the fields are replaced after approximately 8 years, the plastic and the rubber all end up in landfills. Meanwhile, just as tires that have been thrown away can catch fire and release many different harmful chemicals into the air and ground water, tire materials and other synthetic rubber can release chemicals into the air we breathe.9 Those chemicals can also get on our skin and even in our mouths. This is an example where what seemed like helpful recycling can instead be harmful.
The tire material and other rubber used on playgrounds can include the following:
- Loose tire shred (rubber mulch) or “crumb” on a surface that can be raked.
- Tire shreds that are combined with a binder and then poured onto a permanent surface
- Tiles made from tire shreds and binder that have been factory-molded, then glued to a playground surface.7
- Colorful rubber that is “poured in place” (PIP) that is not necessarily made from tires but contains many of the same dangerous materials.
Are Playground Surfaces Made With Rubber or Tire Crumb Safe?
There has been increasing evidence that raises concerns about the safety of tire waste as well as new rubber and other synthetic materials used on playground surfaces. While rubber includes some natural rubber (called latex) from rubber trees, it also contains phthalates (chemicals that affect hormones, see Phthalates and Children’s Products), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs) and other chemicals known or suspected to cause adverse health effects.10 PAHs, for example, are natural or human-made chemicals that are made when oil, gas, coal or garbage is burned.11 According to the EPA, breathing air contaminated with PAHs may increase a person’s chance of developing cancer, and the Agency for Toxic Substances and Disease Registry (ATSDR) states that PAHs may increase the risk for cancer and also increase the chances of birth defects.11,12
Engineered Wood Fiber is a natural alternative used in playgrounds. Researchers at Harvard School of Public Health examined levels of lead in poured-in-place rubber playground surfaces and compared them to levels in soil, sand, and wood mulch materials from 28 randomly selected playgrounds in Boston. They found that average lead levels were more than twice as high for rubber as for sand or wood mulch. They concluded that the lower concentrations of lead in sand and mulch “should be used to inform playground design to optimize children’s health.” 13
What the Scientific Studies Say
The California Office of Environmental Health Hazard Assessment (OEHHA) conducted three laboratory studies in 2007 to investigate the potential health risks to children from playground surfaces made from tire waste. One study evaluated the level of chemicals released that could cause harm to children after they have had contact with loose tire shreds, either by eating them or by touching them and then touching their mouth. The other two studies looked at the risk of injury from falls on playground surfaces made from tire waste compared to wood chips, and whether tire shreds could contaminate air or water.7
It would not be ethical to ask children to eat tire shreds, so the researchers created chemical solution that mimicked the conditions of a child’s stomach and placed 10 grams of tire shreds in it for 21 hours at a temperature of 37°C. Researchers then measured the level of released chemicals in the solution and compared them to levels EPA considered risky. The study also mimicked a child touching the tire shreds and then touching her mouth by wiping recycled tire playground surfaces and measuring chemical levels on the wipes. To evaluate skin contact alone, the researchers tested guinea pigs to see if rubber tire playground samples caused any health problems. This study assumed that children would be using the playground from the ages of 1 through 12. Results of the OEHHA studies showed that a single incident of eating or touching tire shreds would probably not harm a child’s health, but repeated or long-term exposure might. Five chemicals, including four PAHs, were found on wipe samples. One of the PAHs, “chrysene,” was higher than the risk level established by the OEHHA, and therefore, could possibly increase the chances of a child developing cancer.7
A study for the New Jersey Department of Environmental Protection analyzed lead and other metals in particulate matter (dust) that is kicked up into the air by activity on the field, and thus, able to be inhaled, on 5 artificial turf fields.14 The study found that there was more inhalable particulate matter in the air around a moving object (such as a child soccer player) than a stationary collection system on the side of the field. This suggests that studies using stationary collection systems underestimate exposures. It also suggests that even low levels of activity on the field can cause particulate matter to get into the air where it can be inhaled and thus be harmful. The oldest field studied (8 years old) had more inhalable particulate matter than the younger fields (1-3 years old) in this study. The authors state, “the results suggest that there is a potential for inhalable lead to be present on turf fields that have significant amounts of lead present as detectable by surface wipes. Since no level of lead exposure is considered safe for children, “only a comprehensive mandated testing of fields can provide assurance that no health hazard on these fields exists from lead or other metals used in their construction and maintenance.”
A 2013 study analyzing rubber mulch taken from children’s playgrounds in Spain found harmful chemicals in all, often at high levels.10 Twenty-one samples were collected from 9 playgrounds in urban locations. The results showed that all samples contained at least one hazardous chemical, most contained high concentrations of several PAHs, and all released hazardous chemicals into the air, where they can be inhaled. Several of the identified PAHs can be released into the air by heat, and when that happens children are likely to inhale them. While the heat needed to do this was very high in some cases (140ºF/ 60ºC), many of the chemicals also became airborne at a much lower temperature of 77ºF (25ºC). The authors conclude, “The present study highlights the presence of a high number of harmful compounds, frequently at high or extremely high levels, in these recycled rubber materials. Therefore, they should be carefully controlled, and their final use should be restricted or even prohibited in some cases.” 10
A 2014 study evaluated recycled rubber infill that was either already installed or was yet to be installed, as well as one new sample from virgin rubber.15 It found that levels of cadmium and zinc exceeded regulatory requirements for some or all samples, respectively. It also found very high levels of PAHs released into the air from some samples. After calculating a risk assessment for PAH inhalation from synthetic fields, the authors stated that “the quantity of toxic substances it releases when heated does not make it safe for public health.”
A 2018 study examined particulate matter and chemicals from 1 sample of recycled tire rubber, 2 new tire rubber, a single 7-year-old sample of natural rubber, and 1 sample of last-generation thermoplastic elastomer crumb (TPE).16 The recycled tire rubber had a greater concentration of toxic elements, such as heavy metals. TPE released the lowest amount of elements with high concentrations of only magnesium and calcium. Natural rubber was more sensitive to aging and more easily broke down into small pieces that could be inhaled. The authors concluded, “The use of natural rubber and of not-recycled thermoplastic materials, which are progressively replacing recycled tire scraps as synthetic turf fillers, does not seem to be adequately safe for human health, particularly when considering that children are the most exposed bracket of population. Exposure risks arising from the use of these materials deserve to be further deepened.”
A 2018 study in Spain evaluated the amount of chemicals released into the air from samples of recycled tire rubber infill from 15 soccer fields.17 They found high levels of PAHs, including the highly toxic B[a]P. The levels of PAHs exceeded REACH Regulations for consumer products. The study also found heavy metals such as cadmium, chromium and lead, as well as phthalates, adipates, vulcanizing agents and antioxidants that could leach into runoff. They concluded that “The environmental and health risks derived from the use of these surfaces have to be considered and some regulations should be adopted.
A 2018 report by Yale scientists analyzed the chemicals found in 6 samples of tire crumbs from different companies that install school athletic fields, and 9 different samples taken from 9 different unopened bags of rubber mulch intended for household use. The researchers detected 92 chemicals in the samples. A little under a half have never been studied for their health effects, so their risks are unknown, and the other chemicals have been tested for health effects, but those tests were not thorough. Based on the studies that were done, 20% of the chemicals that had been tested are considered to probably can cause cancer, and 40% are irritants that can cause breathing problems such as asthma, and/or can irritate skin or eyes.18 They concluded that “ people routinely ingest, inhale, handle, and have abrasions which contact ground tire material. That being so, it is prudent to assume that any chemicals in the tires or released by them can be transferred to exposed individuals. This study shows that a large number of compounds, many of them carcinogenic or irritants, are released from shredded recycled tires through several potential routes. Caution would argue against use of these materials where human exposure is likely, and this is especially true for playgrounds and athletic playing fields where young people may be affected.”
A 2019 Yale study based on previously published research, identified 306 chemicals found in crumb rubber.19 Fifty-two of these chemicals were classified as carcinogens by the U.S. EPA and/or the European ECHA. Then the researchers used the known characteristics of each chemical, such as the structure, to predict whether or not it was likely to be a carcinogen. Using this process, 197 were predicted to be carcinogens. They concluded, “Our study highlights a vacuum in our knowledge about the carcinogenic properties of many chemicals in crumb rubber infill.” “The crumb rubber infill of artificial turf fields contains or emits chemicals that can affect human physiology.”
Out of the 32 playgrounds surfaced in recycled tires that the researchers in California looked at, only 10 met that state’s 2007 standard for “head impact safety” to reduce brain injury and other serious harm in children who fall while playing. In contrast, all five surfaces made of wood chips met the safety standard.7
Artificial turf fields get hard over time, and so hardness is supposed to be tested annually; unfortunately, many fields are not tested as recommended. When concerned parents and public health advocates convinced Washington, D.C. government officials to test the hardness of artificial turf fields at schools, more than 20% of the 52 fields tested failed, even though the city used less stringent standards for failing than the turf industry recommends.20
NCHR’s own research on the heat of artificial turf fields and playgrounds found that on warm or sunny days, the heat of these surfaces can be 60 degrees or hotter than the temperature of the air or of natural grass. So, for example on a 90 degree day, the grass is also approximately 90 degrees, but artificial turf and rubber playgrounds can exceed 150 degrees Fahrenheit.
What the EPA Says
The EPA created a working group that collected and analyzed data from playgrounds and artificial turf fields that used tire material. Samples were collected at six turf fields and two playgrounds in four study sites (Maryland, North Carolina, Georgia and Ohio). In a report released in 2009, the agency concluded that the level of chemicals monitored in the study and detected in the samples were “below levels of concern.” However, the study did not measure the concentration of organic chemicals that are known to vaporize during summer heat (called SVOCs). SVOCs include PAH. And, the EPA concluded that while there were currently no human studies available to determine the effects of PAHs at various levels, based on laboratory findings, “breathing PAHs and skin contact seem to be associated with cancer in humans.” 11
A meeting was convened by the EPA in 2010, bringing together various state and federal agencies to discuss safe levels of chemical exposure on playgrounds made from tire rubber, and opportunities for additional research. When announcing the results of the study, EPA joined other organizations in recommending that as a precaution, young children wash their hands frequently after playing outside.21
n February 2016, the U.S. government announced a new action plan involving four U.S. government agencies: the EPA, Centers for Disease Control and Prevention (CDC), Agency for Toxic Substances and Disease Registry (ATSDR) and Consumer Product and Safety Commission (CPSC). In December 2016, they released a status report 22 and in July 2019 they released a final report. The latter concluded that many chemicals were found in tire crumb rubber found in tire recycling plants that produce artificial turf and in artificial turf infill “including a range of metals, PAHs, phthalates and other tire rubber related chemicals.” 23 The EPA report also specified that “VOC and SVOC laboratory chamber emission experiments provided information about the potential for chemicals associated with tire crumb rubber to be released into the air and to become available for inhalation exposure.” The report was not a risk assessment and it specified that EPA did not study tire crumb “fine particles and nanoparticles” or the impact on children.22 Our review of the EPA report indicates that the authors state that more research is needed before determining the likely risks to children, and yet the EPA website for the report downplays the risks and seems aimed at reassuring the public rather than providing an objective summary.24
We agree with experts who have also noted that the EPA’s summary ignored the cumulative impact of exposures to chemicals and lead in artificial turf. For example, Jeff Gearhart, Research Director at the Ecology Center, told NCHR that “Even at the EPA’s low estimate of 3% bioavailability, a child ingesting a 3,000-4,000 ppm lead shred would contribute to lead poisoning.” The EPA report estimated that only 3% of the lead in the rubber would remain in the body during digestion. However, because high levels of lead have been found in tire crumb rubber, a child could still get a lot of lead from eating a small amount of rubber.
What is the Impact on Our Environment?
Although this article focuses on the impact of artificial turf on health, it is worth noting that artificial turf also has a negative impact on the environment. Sarah-Jeanne Royer, PhD, a postdoctoral fellow at the University of Hawaii who has published research on the impact of degrading plastic on greenhouse gasses, explained to National Center for Health Research staff that artificial turf fields are made of polyethylene and sometimes nylon so they produce greenhouse gasses.25 The “outgassing” from the plastic is higher during the day but continues at lower levels at night. Because the artificial turf fields have millions of fragments, they have a very high surface area that produces much more greenhouse gas than a flat carpet would.
How to Protect your Children
So how can you protect your child at the playground? Remember that children are much more likely to be harmed by exposure to chemicals in their environment than adults because they are smaller (so the exposure is greater) and because their bodies are still developing. This is why it’s important to significantly reduce (or try to eliminate) any contact your child may have with substances that are known or suspected to be harmful. If you have more than one playground in your area, choose the one that doesn’t have a recycled rubber play surface or other types of rubber or synthetic surface.
Parents can actively persuade local officials that playgrounds should use wood chips rather than rubber or other substances that are less safe when children fall, and more dangerous in terms of chemicals that they breathe or get on their hands.
The CDC, Consumer Product Safety Commission (CPSC) and EPA all recommend that you teach your child the importance of frequent hand washing, especially after playing outside and before eating.20 The President’s Cancer Panel advised to “minimize children’s exposure to toxics” and “both mothers and fathers should avoid exposure to endocrine-disrupting chemicals and known or suspected carcinogens prior to a child’s conception and throughout pregnancy and early life, when risk of damage is greatest.” 26
The Consumer Product Safety Commission recommends the following precautions:
- Avoid mouth contact with playground surfacing materials, including mouthing, chewing, or swallowing playground rubber. This may pose a choking hazard, regardless of chemical exposure.
- Avoid eating food or drinking beverages while directly on playground surfaces, and wash hands before handling food.
- Limit the time at a playground on extremely hot days.
- 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.
- Clean any toys that were used on a playground after the visit.26
To learn more about artificial turf and concerns about cancer risks for kids and young adults, watch this ESPN news video here.
All articles on our website have been approved by Dr. Diana Zuckerman and other senior staff.
- Claudio L. Synthetic Turf-Health Debate Takes Root. Environmental Health Perspectives. 2008;116(3):A117-22. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2265067/
- New York State Department of Health. Fact Sheet: Crumb-Rubber Infilled Synthetic Turf Athletic Fields. August 2012 (last revised). http://www.health.ny.gov/environmental/outdoors/synthetic_turf/crumb-rubber_infilled/fact_sheet.htm
- Dubois L. Artificial Turf Controversy a Constant in Backdrop of Women’s World Cup. Sports Illustrated. June 24, 2015. http://www.si.com/planet-futbol/2015/06/23/womens-world-cup-artificial-turf-canada.
- Goff S. Women’s World Cup will be played on lush, green artificial turf. Washington Post. June 5, 2015. https://www.washingtonpost.com/sports/womens-world-cup-will-be-played-on-lush-green-artificial-turf/2015/06/05/a786a0ac-0b8d-11e5-951e-8e15090d64ae_story.html
Baxter K. Women’s World Cup to Go Forward on Artificial Turf. Los Angeles Times. January 21, 2015. https://www.latimes.com/sports/sportsnow/la-sp-sn-womens-world-cup-lawsuit-artificial-turf-20150121-story.html
Woodall C. ‘Running out of room’: How old turf fields raise potential environmental, health concerns. York Daily Record. November 18, 2019. https://www.ydr.com/in-depth/news/2019/11/18/old-artificial-turf-fields-pose-huge-waste-problem-environmental-concerns-across-nation/2314353001/
- State of California-Office of Environmental Health Hazard Assessment (OEHHA), Contractor’s Report to the Board. Evaluation of Health Effects of Recycled Waste Tires in Playground and Track Products. January 2007. http://www.calrecycle.ca.gov/publications/Documents/Tires%5C62206013.pdf
- Rubber Manufacturers Association. US Scrap Tire Markets 2013. November 2014. https://rma.org/sites/default/files/US_STMarket2013.pdf
- US Environmental Protection Agency (EPA). Wastes-Resource Conversation-Common Wastes & Materials – Scrap Tires (Frequent Questions). http://www.homepages.ed.ac.uk/shs/Hurricanes/Frequent%20Questions%20%20%20Scrap%20Tires%20%20%20US%20EPA.html
- Llompart M, Sanchez-Prado L, Lamas JP, Garcia-Jares C, et al. Hazardous Organic Chemicals in Rubber Recycled Tire Playgrounds and Pavers. Chemosphere. 2013;90(2):423-431. http://www.sciencedirect.com/science/article/pii/S0045653512009848
- US Environmental Protection Agency (EPA). Polycyclic Aromatic Hydrocarbons (PAHs)-Fact Sheet. November 2009. https://www.epa.gov/north-birmingham-project/polycyclic-aromatic-hydrocarbons-pahs-fact-sheet
- Agency for Toxic Substances and Disease Registry (ATSDR). Polycyclic Aromatic Hydrocarbons. September 1996. http://www.atsdr.cdc.gov/toxfaqs/tfacts69.pdf
- Almansour KS, Arisco NJ, Woo MK, et al. Playground Lead Levels in Rubber, Soil, Sand, and Mulch Surfaces in Boston. PLoS One. 2019;14(4):e0216156. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0216156
- Shalat SL. An evaluation of potential exposures to lead and other metals as the result of aerosolized particulate matter from artificial turf playing fields. 2011. New Jersey Department of Environmental Protection. http://www.nj.gov/dep/dsr/publications/artificial-turf-report.pdf
- Marsili L, Coppola D, Bianchi N, et al. Release of polycyclic aromatic hydrocarbons and heavy metals from rubber crumb in synthetic turf fields: Preliminary hazard assessment for athletes. Journal of Environmental & Analytical Toxicology. 2014;5(2):265 http://dx.doi.org/10.4172/2161-0525.1000265
- Canepari S, Castellano P, Astolfi ML, et al. Release of particles, organic compounds, and metals from crumb rubber used in synthetic turf under chemical and physical stress. Environmental Science and Pollution Research International. 2018;25(2):1448-1459. https://doi.org/10.1007/s11356-017-0377-4
- Celeiro M, Dagnac T, Llompart M. Determination of priority and other hazardous substances in football fields of synthetic turf by gas chromatography-mass spectrometry: A health and environmental concern. Chemosphere. 2018;195:201-211. https://doi.org/10.1016/j.chemosphere.2017.12.063
- Benoit G, Demars S. Evaluation of organic and inorganic compounds extractable by multiple methods from commercially available crumb rubber mulch. Water, Air, & Soil Pollution. 2018;229(3):64. https://doi.org/10.1007/s11270-018-3711-7
- Perkins AN, Inayat-Hussain SH, Deziel NC, et al. Evaluation of potential carcinogenicity of organic chemicals in synthetic turf crumb rubber. Environmental Research. 2019;169:163-172. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396308/
- Sadon R. Hardness test results reveal wider scope of artificial turf failures. DCist. October 12, 2017. https://dcist.com/story/17/10/12/even-more-artificial-turf-fields-fa/
- US Environmental Protection Agency (EPA). Fact Sheet – The Use of Recycled Tire Materials on Playgrounds & Artificial Turf Fields. http://www.emcmolding.com/uploads/files/file130102132640.pdf
- EPA. Federal Research on Recycled Tire Crumbs Used on Playing Fields. December 2016. https://www.epa.gov/sites/production/files/2016-12/documents/federal_research_action_plan_on_recycled_tire_crumb_used_on_playing_fields_and_playgrounds_status_report.pdf.
- EPA. Synthetic Turf Field Recycled Tire Crumb Rubber Research Under the Federal
Research Action Plan: FINAL REPORT PART 1–TIRE CRUMB RUBBER CHARACTERIZATION VOLUME 1. July 2019. https://www.epa.gov/sites/production/files/2019-08/documents/synthetic_turf_field_recycled_tire_crumb_rubber_research_under_the_federal_research_action_plan_final_report_part_1_volume_1.pdf
- EPA. July 2019 Report: Tire Crumb Rubber Characterization. https://www.epa.gov/chemical-research/july-2019-report-tire-crumb-rubber-characterization-0
- Astroturf. https://www.astroturf.com/synthetic-turf-products/sports-grass-infill/
- Reuben S. Reducing Environmental Cancer Risk What We Can Do Now. Annual Report President’s Cancer Panel. U.S. Department of Health and Human Services. 2010. https://deainfo.nci.nih.gov/advisory/pcp/annualReports/pcp08-09rpt/PCP_Report_08-09_508.pdf.
- CPSC. Crumb Rubber Information Center. https://www.cpsc.gov/Safety-Education/Safety-Education-Centers/Crumb-Rubber-Safety-Information-Center