Nyedra W. Booker, PharmD, MPH and Stephanie Fox-Rawlings, PhD
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 during the 1960s primarily for athletic fields, these artificial surfaces were also part of a strategy to provide children with more opportunities for outdoor physical activity, particularly in the inner city where outdoor playgrounds were scarce. The first artificial turf (marketed as “Chemgrass”) was made of plastic, yet looked a lot like natural grass. Since then, 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, while 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. 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. 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. 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 are suing the FIFA.
Some of the benefits of artificial turf are that it’s a long-lasting “all-weather” material that does not require a lot of maintenance in the short-term or potentially dangerous pesticides. Artificial turf is currently used on more than 12,000 athletic fields in the U.S. Unfortunately, these surfaces often don’t last as long as expected.
From the Tire Swings to Play Surfaces Made from Tires
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.  In 2013, approximately 233 million scrap tires were generated, of which 8% (approximately 17.5 million tires) was processed for playground surface cover and 4% (almost 10 million tires) for sports surfaces.  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. But 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. 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.
- 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 Recycled Tires 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 natural rubber 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. PAHs, for example, are natural or human-made chemicals that are made when oil, gas, coal or garbage is burned. 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.
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.
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.
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.
A 2012 study analyzing rubber mulch taken from children’s playgrounds in Spain found harmful chemicals in all, often at high levels. Twenty-one samples were collected from 9 playgrounds in urban locations. The results showed that all samples contained at least one hazardous chemical, and most contained high concentrations of several PAHs. 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 (140 degrees Fahrenheit/ 60 ºC), many of the chemicals also became airborne at a much lower temperature of 77 ºF (25 ºC). The authors concluded that the use of rubber recycled tires on playgrounds “should be restricted or even prohibited in some cases.”
A 2015 report by Yale scientists analyzed the chemicals found in 5 samples of tire crumbs from 5 different companies that install school athletic fields, and 9 different samples taken from 9 different unopened bags of playground rubber mulch. The researchers detected 96 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.
What the EPA Has Done
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.” There were limitations to this study, however. The study did not measure the concentration of organic chemicals that are known to vaporize during summer heat (called SVOCs). SVOCs include PAH.
Due to the small number of samples and sampling sites used, the EPA stated that it is not possible to know if these findings are typical of other playgrounds or fields until additional studies are conducted. 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.
A meeting was then 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. In the case of PAHs, the EPA has concluded that while there are currently no human studies available to determine their effects at various levels, based on laboratory findings, “breathing PAHs and skin contact seem to be associated with cancer in humans.” 
In February 2016, the U.S. government announced a new action plan to better understand the likely health risks of tire crumb and similar artificial surfaces. This initiative involves 4 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. 
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. 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.”
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.
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.
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