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NCHR Comments on CPSC Priorities for FY2021/2022

National Center for Health Research, April 2020


Diana Zuckerman, Ph.D., President of the National Center for Health Research

Comments on the U.S. Consumer Product Safety Commission
Agenda and Priorities for FY2021/2022

April 2020

The National Center for Health Research is a nonprofit research center staffed by scientists, medical professionals, and public health experts who analyze and review research on a range of health issues. Thank you for the opportunity to share our views concerning the Consumer Product Safety Commission’s (CPSC) priorities for fiscal years 2021 and 2022. We greatly respect the essential role of the CPSC, as well as the challenges you face in selecting the most important priorities.

We want to start by emphasizing two issues involving chemicals in products that affect our and our children’s health, (1) artificial turf and playground surfaces and equipment, and (2) organohalogen flame retardants. We will also briefly discuss sport and recreational helmets, sleep-related products for infants, furniture stability, home elevators, and liquid nicotine packaging. All these issues should be CPSC priorities.

Artificial Turf and Playgrounds: Risky Chemicals and Lead

We expressed our concerns about artificial turf and playgrounds last year. Our concerns are even greater this year because of increasing evidence of lead exposure from these products, as well as from playground equipment.

Requiring testing for artificial turf, playground surfaces, and the paint used for playground equipment needs to be a priority, because children are exposed to these synthetic rubber and plastic fields and playground surfaces as well as playground equipment – and the lead and harmful chemicals they contain – day after day, year after year.

A new issue that arose in the last year is research indicating that the paint used on outdoor playground equipment contains lead. Professor Alexander Wooten from Morgan State conducted studies in Maryland that indicate that paint with lead is widely used on playground equipment, such as climbing structures, in some cases at very dangerous levels.1 We have learned that there are no federal restrictions on lead used in outdoor paint, even for products used exclusively by young children. CPSC should investigate this issue immediately.

The rubber and plastic that make up turf and playground surfaces contain chemicals with known health risks, which are released into the air and get onto skin and clothing. Crumb rubber – whether from recycled tires or “virgin rubber”– includes endocrine disruptors such as phthalates, heavy metals such as lead and zinc, as well as other carcinogens and skin irritants such as some polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs).2,3,4,5,6 Other plastic or rubber surfaces used in playgrounds also contain many of these chemicals.7 Moreover, the plastic grass in artificial turf also has dangerous levels of lead, PFAS, and other toxic chemicals as well. PFAS are of particular concern because they are “forever chemicals” that get into the human body and are not metabolized, accumulating over the years. Replacing tire waste with silica, zeolite, and other materials also has substantial risks.

Tire crumb is widely used as infill for artificial turf fields and also used for colorful rubber playground surfaces. In addition to the chemicals noted above, these playground surfaces contain lead and create lead dust on the surface that is invisible to the eye but that children are breathing in when they play.8

The CPSC is well aware that no level of lead exposure is safe for children, because lead can cause cognitive damage even at low levels. Some children are even more vulnerable than others, and this vulnerability can be difficult or even impossible to predict. Since lead has been found in tire crumb as well as new synthetic rubber, it is not surprising that numerous artificial turf fields and playgrounds made with either tire crumb or “virgin” rubber have been found to contain lead. However, the Centers for Disease Control and Prevention (CDC) also warns that the “plastic grass” made with nylon or other materials also contain lead. Whether from infill or from plastic grass, the lead doesn’t just stay on the surface – it can get into clothes, on the skin, or into the air that children breathe.

While one-time or sporadic exposures are unlikely to cause long-term harm, children’s repeated exposures, especially during critical developmental periods, raise the likelihood of serious harm. There are few activities that children engage in for as many hours in their early years as those on playgrounds and playing fields.

We appreciate the CPSC’s ongoing efforts to investigate the safety of crumb rubber on playgrounds and playing fields. As your study using focus groups to examine children’s use of playgrounds and exposure to playground surfaces has shown, children who use playgrounds with artificial surfaces could be exposed to the chemicals in these surfaces.9 It is unfortunate that the EPA report on artificial turf (which did not include playground surfaces or playground materials) did not provide the scientific evidence needed to support their assumptions that the likely levels of exposure to dangerous chemicals was low enough that it was not likely to harm children. The EPA did not study the actual impact of the exposure to endocrine disrupting chemicals on children and did not study lead exposure from synthetic playground surfaces, leaded paint used on playground equipment, or artificial turf.10

Meanwhile, we have repeatedly heard the companies that make these products and those that install them make erroneous claims at the state and local government levels, falsely stating that CPSC and other federal agencies have concluded that these materials are proven safe. As we all know, that is not correct.

We encourage you to closely evaluate the research that has been done, focusing on independently funded research of short-term and long-term safety issues. We need information that can protect our children from harm. In addition, we strongly urge you to convene a Chronic Hazard Advisory Panel (CHAP) to examine the short-term and long-term risks of different types of artificial turf used in playing fields and children’s playgrounds, including surfaces and lead paint used on climbing equipment and other materials.

In addition to the risks of lead and the long-term risks of cancer and other health problems caused by hormone disruption, these fields can cause short-term harms. Artificial turf generates dust which may exacerbate children’s asthma.11,12 Fields heat up to temperatures far higher than ambient temperature, reaching temperatures that are more than 70 degrees warmer than nearby grass; for example, 180 degrees when the temperature is in the high 90’s and 150-170 degrees on a sunny day when the air temperature is only in the 70’s.13,14 We have measured the temperatures ourselves and been shocked by the results. These temperatures can cause heat stress and burns.

Fields made of crumb rubber have been marketed as reducing injuries compared to grass. However, research has shown that this is not the case. We have spoken to students terribly harmed by turf burn, and studies have indicated increased risk for some types of injuries, including joint, foot, and brain injuries.15,16,17 That is the reason that only two Major League Baseball parks use artificial turf and why the men’s soccer World Cup is now always played on grass.  In response to the demands of women soccer players, the Women’s World Cup will require grass in 2023.

Organohalogen Flame Retardants

The National Academies of Sciences, Engineering, and Medicine issued their scoping plan to assess the hazards of organohalogen flame retardants (OFRs) last year.18 The report concluded that OFRs can be divided into subclasses on the basis of chemical structure, physicochemical properties, and predicted biologic activity. As noted in their summary of the report:

The committee identified 14 subclasses that can be used to conduct a class-based hazard assessment and concluded that the best approach is to define subclasses as broadly as is feasible for the analysis; defining subclasses too narrowly could defeat the purpose of a class approach to hazard assessment.

We encourage you to convene a CHAP to use this scoping plan to evaluate OFRs and to develop regulations to address OFRs in children’s products, upholstered residential furniture, mattresses/mattress pads, and the plastic casing of electronic devices. In addition, it is essential to consider current flammability standards to determine if there are changes that would improve their safety from chemical exposures as well as exposures during a fire.

OFRs are not bound to products to which they are added, so they migrate out of products and into dust. This allows them to get onto our skin and food and into the air. Because of their widespread use and the long-lasting nature of OFRs, consumers are continuously exposed to OFRs19 and many bioaccumulate in our food supply.20,21 As a result, OFRs are present in nearly all people in the U.S.22,23 For these reasons, CPSC should focus on the potential for hormone disruption, altered brain development, reduced ability to get and stay pregnant, and the timing of puberty.24,25 While not all OFRs have been adequately studied to determine whether all are unsafe, those that have been sufficiently studied have proved to be harmful to health.

We share the Commission’s concerns about fire hazards as well, but there is evidence that these flame retardants may not be effective at preventing deaths in real world situations.26,27 When the chemicals burn during a fire, the inhaled smoke is more toxic to humans, and exposures could result in serious harms, including death.

Helmets for Sport and Recreational Activities

There are up to 3.8 million concussions reported each year related to sport or recreational activities, with most reported for children and adolescents.28 This number is likely an underestimate.29 We urge the CPSC to focus greater attention on the need to ensure the effectiveness of helmets intended to protect against brain injuries during athletic activities. Currently, CPSC only provides guidelines for bicycle helmets, even though many organized sports and recreational activities use helmets to reduce the risk for severe head injuries, including baseball, football, snow sports, skiing/snowboarding, and climbing. Unfortunately, these helmets are not necessarily designed to prevent mild concussions.30 We encourage CPSC to consider how design changes could improve the ability of helmets to prevent severe head injuries as well as mild concussions, and to develop guidelines for helmets that reduce these risks without interfering with vision or hearing or other safety concerns.

Baby Products and Products Posing Risks to Young Children

The CPSC is the major safeguard to protect infants and young children from unsafe products that are widely sold and inadequately studied. Crib bumpers and infant sleepers are two examples that have received CPSC attention but CPSC has not adequately protected families from the tragedies of infant deaths caused by these products.

There is nothing more tragic than when an infant or young child dies due to a product in the home that families or loved ones purchased because they erroneously assumed they were tested and found to be safe. The standard for these products should not be based on the number of deaths per year, but rather the 1) risk to benefit ratio of the product and 2) whether regulations or restrictions would make the product safer. In the case of crib bumpers, they have no benefit. In the case of inclined infant sleepers, products were sold that were promoted as superior to other available products but in fact had no comparative benefits and were less safe.

Furniture that tips over and home elevators are two other examples of products that have resulted in deaths of young children. In both cases, CPSC should do more to prevent the sale of products that can be redesigned or modified to make them safe.

Liquid Nicotine Packaging

We agree with other public health and consumer organizations that have urged CPSC to immediately remove from the market dangerous liquid nicotine products lacking the child-resistant packaging and flow restrictors required under the Child Nicotine Poisoning Prevention Act of 2015. The law requires the CPSC to enforce a mandatory child-resistant packaging standard for liquid nicotine containers, including the use of flow restrictors.

Liquid nicotine is a highly toxic product that can seriously harm or kill children. Since liquid nicotine can be quickly absorbed through the skin, flow restrictors are an essential safeguard to reduce the risk of nicotine poisoning in children.

Effective CPSC enforcement measures to remove noncompliant products from the market are long overdue, and that enforcement should be an immediate priority.

Final Thoughts

CPSC is the only federal agency whose mission is to protect children and adults from harmful products used in their daily life. Flame retardants and lead and many different chemicals in artificial turf and playground surfaces and equipment get into the air and dust and thus into our bodies. These chemicals tend to have greater risks for fetuses and children. There are large gaps in our knowledge about the chemicals in the products on the market, because the companies do not provide that information to the public. Ideally, the potential health impact of all of these chemicals would be evaluated in the final product before it was sold. If that doesn’t happen, CPSC must do more to identify the health risks as soon as possible after children and adults have been exposed.

Too often, the lack of independently funded and publicly available research has been used to mislead the public. Claims that “there is no evidence of harm” are misunderstood to mean “there is no harm.”

While reducing exposures to dangerous products is key, there will always be some potential for harm. Whether those harms are from the intended use of a consumer product or an unintended but foreseeable use, CPSC has a very important role to play in reducing harm. Improving the timeliness and targeting of information campaigns to warn parents and children about harmful products is also a key task of the CPSC.

References

  1. Wooten, Alexander, Lead and Playgrounds, Presentation at the Takoma community forum in Washington, DC, July 29, 2019.
  2. California Office of Environmental Health Hazard Assessment (OEHHA). Evaluation of Health Effects of Recycled Waste Wires in Playground and Track Products. Prepared for the California Integrated Waste Management Board. 2007. https://www2.calrecycle.ca.gov/Publications/Details/1206
  3. Llompart M, Sanchez-Prado L, Lamas JP, et al. Hazardous organic chemicals in rubber recycled tire playgrounds and pavers. Chemosphere. 2013;90(2):423-431. https://www.ncbi.nlm.nih.gov/pubmed/22921644/
  4. 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 and Analytical Toxicology. 2014;5(2):1133-1149. https://www.hilarispublisher.com/open-access/release-of-polycyclic-aromatic-hydrocarbons-and-heavy-metals-from-rubber-crumb-in-synthetic-turf-fields-2161-0525.1000265.pdf
  5. 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;229:64. https://link.springer.com/article/10.1007/s11270-018-3711-7
  6. Perkins AN, Inayat-Hussain SH, Deziel NC, et al. Evaluation of potential carcinogenicity of organic chemicals in synthetic turf crumb rubber. Environmental Research. 2018;169:163–172. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396308/
  7. KimS, Yang JY, Kim HH, et al. Health risk assessment of lead ingestion exposure by particle sizes in crumb rubber on artificial turf considering bioavailability. Environmental Health and Toxicology. 2012;27:e2012005. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3278598/
  8. Baca, N. Parents demand answers on playground lead in DC. wusa9.com. October 2, 2019. https://www.wusa9.com/article/news/local/dc/parent-forum-lead-playgrounds/65-45401b01-3371-436a-8f55-a364be0c07d3
  9. Consumer Product Safety Commission. Summary of Playground Surfacing Focus Groups. 2018. https://www.cpsc.gov/s3fs-public/Playground_Surfacing_Focus_Group_Report_2018.pdf
  10. National Center for Health Research. Children and Athletes at Play on Toxic Turf and Playgrounds. Center4research.org. http://www.center4research.org/children-athletes-play-toxic-turf-playgrounds/
  11. Shalat, SL. An Evaluation of Potential Exposures to Lead and Other Metals as the Result of Aerosolized Particulate Matter from Artificial Turf Playing Fields. Submitted to the New Jersey Department of Environmental Protection. 2011. http://www.nj.gov/dep/dsr/publications/artificial-turf-report.pdf
  12. Mount Sinai Children’s Environmental Health Center. Artificial Turf: A Health-Based Consumer Guide. 2017. http://icahn.mssm.edu/files/ISMMS/Assets/Departments/Environmental%20Medicine%20and%20Public%20Health/CEHC%20Consumer%20Guide%20to%20Artificial%20Turf%20May%202017.pdf
  13. Serensits TJ, McNitt AS, Petrunak DM. Human health issues on synthetic turf in the USA. Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology. 2011;225(3):139-146. https://plantscience.psu.edu/research/centers/ssrc/documents/human-health-issues-on-synthetic-turf-in-the-usa.pdf
  14. Penn State’s Center for Sports Surface Research. Synthetic Turf Heat Evaluation- Progress Report. 2012. http://plantscience.psu.edu/research/centers/ssrc/documents/heat-progress-report.pdf
  15. Theobald P, Whitelegg L, Nokes LD, et al. The predicted risk of head injury from fall-related impacts on to third-generation artificial turf and grass soccer surfaces: A comparative biomechanical analysis. Sports Biomechanics. 2010;9(1):29-37. https://www.ncbi.nlm.nih.gov/pubmed/20446637
  16. Balazs GC, Pavey GJ, Brelin AM, et al. Risk of anterior cruciate ligament injury in athletes on synthetic playing surfaces: A systematic review. American Journal of Sports Medicine. 2015;43(7):1798-804. https://www.ncbi.nlm.nih.gov/pubmed/25164575
  17. Mack CD, Hershman EB, Anderson RB, et al. Higher rates of lower extremity injury on synthetic turf compared with natural turf among national football league athletes: Epidemiologic confirmation of a biomechanical hypothesis. American Journal of Sports Medicine. 2019;47(1):189-196. https://www.ncbi.nlm.nih.gov/pubmed/30452873
  18. National Academies of Sciences, Engineering, and Medicine; Division on Earth and Life Studies; Board on Environmental Studies and Toxicology; Committee to Develop a Scoping Plan to Assess the Hazards of Organohalogen Flame Retardants. A Class Approach to Hazard Assessment of Organohalogen Flame Retardants. Washington (DC): National Academies Press (US). 2019. https://www.ncbi.nlm.nih.gov/books/NBK545458/
  19. Allgood JM, Vahid KS, Jeeva K, et al. Spatiotemporal analysis of human exposure to halogenated flame retardant chemicals. Science of the Total Environment. 2017;609:272-276. https://www.ncbi.nlm.nih.gov/pubmed/28750230
  20. Lupton SJ, Hakk H. Polybrominated diphenyl ethers (PBDEs) in US meat and poultry: 2012-13 levels, trends and estimated consumer exposures. Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment. 2017;34(9):1584-1595. https://www.ncbi.nlm.nih.gov/pubmed/28604253
  21. Schecter A, Colacino J, Patel K, et al. Polybrominated diphenyl ether levels in foodstuffs collected from three locations from the United States. Toxicology and Applied Pharmacology. 2010;243(2):217-224. https://www.ncbi.nlm.nih.gov/pubmed/19835901
  22. Centers for Disease Control and Prevention. Fourth National Report on Human Exposure to Environmental Chemicals, Updated Tables. 2019. http://www.cdc.gov/exposurereport/
  23. Ospina M, Jayatilaka N, Wong LY, et al. Exposure to organophosphate flame retardant chemicals in the U.S. general population: Data from the 2013-2014 National Health and Nutrition Examination Survey. Environment International. 2017;110:32–41. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6261284/
  24. Dishaw L, Macaulay L, Roberts SC, et al. Exposures, mechanisms, and impacts of endocrine-active flame retardants. Current Opinion in Pharmacology. 2014;19:125-133. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4252719/
  25. Kim YR, Harden FA, Toms LM, et al. Health consequences of exposure to brominated flame retardants: A systematic review. Chemosphere. 2014;106:1-19. https://www.ncbi.nlm.nih.gov/pubmed/24529398
  26. Shaw SD, Blum A, Weber R, et al. Halogenated flame retardants: Do the fire safety benefits justify the risks? Reviews on Environmental Health. 2010;25:261-305. https://www.ncbi.nlm.nih.gov/pubmed/21268442
  27. McKenna S, Birtles R, Dickens K, et al. Flame retardants in UK furniture increase smoke toxicity more than they reduce fire growth rate. Chemosphere. 2018;196:429-439. https://www.ncbi.nlm.nih.gov/pubmed/29324384
  28. Halstead ME, Walter KD, Moffatt K, et al. Sport-related concussion in children and adolescents. Pediatrics. 2018;142(6):e20183074. https://pediatrics.aappublications.org/content/142/6/e20183074
  29. Baldwin GT, Breiding MJ, Dawn Comstock R. Epidemiology of sports concussion in the United States. Handbook of Clinical Neurology. 2018;158:163-74. https://www.ncbi.nlm.nih.gov/pubmed/30482376
  30. Consumer Product Safety Commission. Which helmet for which activity? https://www.cpsc.gov/safety-education/safety-guides/sports-fitness-and-recreation-bicycles/which-helmet-which-activity
  31. Perry, C. Why Inclined Baby Sleepers Are So Dangerous. Parents.com. November 8, 2019. https://www.parents.com/baby/sleep/basics/why-inclined-baby-sleepers-are-so-dangerous/

CPTF Statement Supporting Maryland House Bill to Ban State Funds for Artificial Turf and Playgrounds

Diana Zuckerman, PhD, National Center for Health Research, March 5, 2020


CPTF Statement Supporting Maryland House Bill 1098
To Ban State Funds for Artificial Turf and Playgrounds
March 5, 2020

Diana Zuckerman, PhD, President

Thank you for the opportunity to express our strong support for of HB 1098, to restrict the funding of additional artificial turf fields and playground surfaces in Maryland.

As a long-time resident of Montgomery County and president of the National Center for Health Research (NCHR), I am hoping that this bill will finally get the support it deserves.  NCHR is a non-profit public health organization which analyzes and explains scientific and medical information that can be used to improve policies, programs, services, and products.

Our organization has been testifying and writing about the dangers of synthetic turf and playground surfaces for several years, and we’ve testified before state, local and federal legislative bodies and regulatory agencies.  Our scientific staff has reviewed all publicly available scientific studies pertaining to the health impact of the lead and toxic chemicals that are in artificial turf and playground surfaces, compared to natural surfaces such as grass and engineered wood fiber.

In the last year, scientists have reported finding potentially dangerous levels of lead in artificial turf fields and playground surfaces.  In addition, plastic and synthetic rubber are made with different types of hormone-disrupting chemicals, some of which are known to be particularly harmful to growing children.  Scientists at the National Institute of Environmental Health Sciences, which is an institute of NIH, have concluded that these chemicals can be threats to health even at low levels.  According to research at Yale University, 20% of the 96 chemicals they found in samples at five different synthetic turf companies were classified as probable carcinogens.[1]

Manufacturers and advocates for synthetic turf often state that artificial turf has been declared safe by federal authorities.  That is completely untrue.  It is essential to understand that there are no federal requirements for safety testing of these synthetic turf products before they are sold.   Although the EPA and the federal Consumer Product Safety Commission are jointly studying the chemicals used in these products, they have not released any data on studies of children exposed to these fields and playgrounds day after day and week after week.

We commend you for considering how to reverse the dangerous trend of replacing natural fields and playground surfaces with materials that are dangerous to our children’s health, potentially dangerous to adult fertility and health, and bad for our environment.  In the last year, we’ve learned new information about lead and PFAS in artificial turf, as well as the risks of some of the newer infill materials that turf companies are using to replace tire crumb.

Tire crumb, used as infill for artificial turf fields and also used for colorful rubber playground surfaces, has well-known risks, containing lead as well as chemicals that have the potential to increase obesity; contribute to early puberty; cause attention problems such as ADHD; exacerbate asthma; and eventually cause cancer.  However, the plastic grass itself has dangerous levels of lead, PFAS, and other toxic chemicals as well.  PFAS are of particular concern because they are “forever chemicals” that get into the human body and are not metabolized, accumulating over the years. Replacing tire waste with silica, zeolite, and other materials also has substantial risks.

Federal agencies such as the EPA and the U.S. Consumer Product Safety Commission have been investigating the safety of these products.  Despite claims to the contrary, none have demonstrated that artificial turf is safe.  Although the Trump Administration’s EPA stated that there was no conclusive evidence that the levels of chemicals in artificial turf was harmful to children, they made it clear that their research was based on assumptions rather than scientific research on children.

Lead

The American Academy of Pediatrics states that no level of lead exposure is safe for children, because lead can cause cognitive damage even at low levels.  Some children are even more vulnerable than others, and that can be difficult or even impossible to predict.  Since lead has been found in tire crumb as well as new synthetic rubber, it is not surprising that numerous artificial turf fields and playgrounds made with either tire crumb or “virgin” rubber have been found to contain lead.  However, the Centers for Disease Control and Prevention (CDC) also warns that the “plastic grass” made with nylon or some other materials also contain lead.  Whether from infill or from plastic grass, the lead doesn’t just stay on the surface.  With wear, the turf materials turn to dust that is invisible to the eye but that children are breathing in when they play.

Why are chemicals that are banned from children’s toys allowed in artificial turf and rubber playground surfaces?

Synthetic rubber and plastic are made with different types of endocrine (hormone) disrupting chemicals (also called EDCs) and other toxins.  There is very good evidence regarding these chemicals in tire crumb, based on studies done at Yale and by the California Office of Environmental Health Hazard Assessment (OEHHA).

The California OEHHA conducted three laboratory studies to investigate the potential health risks to children from playground surfaces made from tire waste.1 The researchers created a 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.  One study 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.  Results of the OEHHA studies showed that 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.

A 2018 report by Yale scientists detected 92 chemicals in samples from 6 different artificial turf companies, including unused bags of tire crumb. Unfortunately, the health risks of most of these chemicals had never been studied.  However, 20% of the chemicals that had been tested are classified as probable carcinogens and 40% are irritants that can cause asthma or other breathing problems, or can irritate skin or eyes.[2]

There are numerous studies indicating that endocrine-disrupting chemicals found in rubber and plastic cause serious health problems. Scientists at the National Institute of Environmental Health Sciences (which is part of NIH) have concluded that unlike most other chemicals, hormone-disrupting chemicals can be dangerous at very low levels, and the exposures can also be dangerous when they combine with other exposures in our environment.

That is why the Consumer Product Safety Commission has banned numerous endocrine-disrupting chemicals from toys and products used by children. The products involved, such as pacifiers and teething toys, are banned even though they would result in very short-term exposures compared to artificial turf or playground surfaces.

A report warning about possible harm to people who are exposed to rubber and other hormone disrupting chemicals at work explains that these chemicals “can mimic or block hormones and disrupt the body’s normal function, resulting in the potential for numerous health effects… Similar to hormones, EDC can function at very low doses in a tissue-specific manner and may exert non-traditional dose–response because of the complicated dynamics of hormone receptor occupancy and saturation.”[3]

Studies are beginning to demonstrate the contribution of skin exposure to the development of respiratory sensitization and altered pulmonary function. Not only does skin exposure have the potential to contribute to total body burden of a chemical, but also the skin is a highly biologically active organ capable of chemical metabolism and the initiation of a cascade of immunological events, potentially leading to adverse outcomes in other organ systems.

Scientific Evidence of Cancer and Other Serious Harm

It is essential to distinguish between evidence of harm and evidence of safety. Like the Trump Administration’s EPA, companies that sell and install artificial turf often claim there is “no evidence children are harmed” or “no evidence that the fields cause cancer.” This is often misunderstood as meaning the products are safe or are proven to not cause harm. Neither is true.

It is true that there no clear evidence that an artificial turf field has caused specific children to develop cancer. However, the statement is misleading because it is virtually impossible to prove any chemical exposure causes one specific individual to develop cancer.

As an epidemiologist, I can also tell you that for decades there was no evidence that smoking or Agent Orange caused cancer.  It took many years to develop that evidence, and the same will be true for artificial turf.

I have testified about the risks of these materials at the U.S. Consumer Product Safety Commission, as well as previous Maryland hearings.  I am sorry to say that I have repeatedly seen and heard scientists paid by the turf industry and other turf industry lobbyists say things that are absolutely false.  They claim that these products are proven safe (not true) and that federal agencies have stated there are no health risks (also not true).

However, we know that the materials being used in artificial turf and rubber playground surfaces contain carcinogens, and when children are exposed to those carcinogens day after day, week after week, and year after year, they increase the chances of our children developing cancer, either in the next few years or later as adults.  That should be adequate reason not to install them in your community.  That’s why I have spoken out about the risks of artificial turf in my community and on a national level.  The question must be asked: if they had all the facts, would Maryland families choose to spend millions of taxpayer dollars on fields that are unhealthy and unsafe rather than well-designed natural grass fields?

Dangerously Hot and Hard Fields

Summers in Maryland can get hot.  Even when the temperature is a pleasant 80 degrees Fahrenheit, artificial turf and playground surfaces can reach 150 degrees or higher.  Obviously, turf and playground surfaces are likely to be even hotter than 150 degrees on a sunny 90 degree day.  That can cause “heat poisoning” as well as burns.

Artificial turf fields get hard as well.  Turf companies recommend annual tests at 10 locations on each turf field, using something called a Gmax scores.  A Gmax score over 200 is considered extremely dangerous and is considered by industry to pose a death risk.  However, the synthetic turf industry and ASTM (American Society for Testing and Materials), suggest scores should be even lower — below 165 to ensure safety comparable to a grass field.  Are Maryland communities paying to have these tests conducted on all public artificial turf fields?

The hardness of natural grass fields is substantially influenced by maintenance, rain and other weather; if the field gets hard, aeration water will make it safe again.  In contrast, once an artificial turf field has a Gmax score above 165, it needs to be replaced because while the scores can vary somewhat due to weather, the scores will inevitably get higher because the turf will get harder.  Gmax testing involves testing 10 different areas of a playing fields, to make sure all are considered safe.  Some officials average those 10 scores to determine safety; however, experts explain that is not appropriate.  If a child (or adult) falls, it can be at the hardest part of the field, which is why safety is determined based on each area tested.

Environmental Issues

In addition to the health risks to school children and athletes, approximately three tons of infill materials migrate off of each synthetic turf field into the greater environment each year.  About 2-5 metric tons of infill must be replaced every year for each field, meaning that tons of the infill have migrated off the field into grass, water, and our homes.  The fields also continuously shed microplastics as the plastic blades break down.[4,5] These materials may contain additives such as PAHs, flame retardants, UV inhibitors, etc., which can be toxic to marine and aquatic life; and microplastics are known to migrate into the oceans, food chain, and drinking water and can absorb and concentrate other toxins from the environment.[6,7,8]

Synthetic surfaces also create heat islands.[9,10]  In contrast, organically managed natural grass saves energy by dissipating heat, cooling the air, and reducing energy to cool nearby buildings.  Natural grass and soil protect groundwater quality, biodegrade polluting chemicals and bacteria, reduce surface water runoff, and abate noise and reduce glare.[11]

Envirofill and Alternative Infills

Envirofill artificial turf fields are advertised as “cooler” and “safer,” but our research indicates that these fields are still at least 30-50 degrees hotter than natural grass. Envirofill is composed of materials resembling plastic polymer pellets (similar in appearance to tic tacs) with silica inside. Silica is classified as a hazardous material according to OSHA regulations, and the American Academy of Pediatrics specifically recommends avoiding it on playgrounds. The manufacturers and vendors of these products claim that the silica stays inside the plastic coating.  However, sunlight and the grinding force from playing on the field breaks down the plastic coating. For that reason, even the product warranty admits that only 70% of the silica will remain encapsulated. The other 30% can be very harmful as children are exposed to it in the air.

In addition, the Envirofill pellets have been coated with an antibacterial called triclosan.  Triclosan is registered as a pesticide with the EPA and the FDA has banned triclosan from soaps because manufacturers were not able to prove that it is safe for long-term use.  Research shows a link to liver and inhalation toxicity and hormone disruption.  The manufacturer of Envirofill says that the company no longer uses triclosan, but they provide no scientific evidence that the antibacterial they are now using is any safer than triclosan.  Microscopic particles of this synthetic turf infill will be inhaled by children, and visible and invisible particles come off of the field, ending up in shoes, socks, pockets, and hair.

In response to the concerns of educated parents and government officials, other new materials are now being used instead of tire crumb and other very controversial materials.  However, all the materials being used (such as volcanic ash, corn husks, and Corkonut) have raised concerns and none are proven to be as safe or effective as well-designed grass fields.

Conclusions

There have never been any safety tests required prior to sale that prove that any artificial turf products are safe for children who play on them regularly.  In many cases, the materials used are not publicly disclosed, making independent research difficult to conduct.  None of these products are proven to be as safe as natural grass in well-constructed fields.

I have cited several relevant scientific articles on artificial turf in this letter, and there are numerous studies and growing evidence of the harm caused by these synthetic materials.  I would be happy to provide additional information upon request (dz@center4research.org).

I am not paid to write this statement.  I am one of the many parents and scientists who are very concerned about the impact of artificial fields on our children.  Your decisions about artificial turf and playground materials will directly and indirectly help educate parents throughout the state, making it even more important that your decision is based on scientific evidence, not on sales pitches by individuals with conflicts of interest.

Officials in communities all over the country have been misled by artificial turf salespeople. They were erroneously told that these products are safe.  But on the contrary, there is clear scientific evidence that these materials are harmful.  The only question is how much exposure is likely to be harmful to which children?  We should not be willing to take such a risk.  Our children deserve better.

Please pass HB 1098 and thank you for addressing this critical public health issue.

 

References

  1. 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
  2. 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;229:64. https://doi.org/10.1007/s11270-018-3711-7
  3. Anderson SE and Meade BJ. Potential Health Effects Associated with Dermal Exposure to Occupational Chemicals. Environmental Health Insights. 2014; 8(Suppl 1):51–62. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270264/
  4. Magnusson K, Eliasson K, Fråne A, et al. Swedish sources and pathways for microplastics to the marine environment, a review of existing data. Stockholm: IVL- Swedish Environmental Research Institute. 2016. https://www.naturvardsverket.se/upload/miljoarbete-i-samhallet/miljoarbete-i-sverige/regeringsuppdrag/utslapp-mikroplaster-havet/RU-mikroplaster-english-5-april-2017.pdf
  5. Kole PJ, Löhr AJ, Van Belleghem FGAJ, Ragas AMJ. Wear and tear of tyres: A stealthy source of microplastics in the environment. International Journal of Environmental Research Public Health. 2017;14(10):pii: E1265. https://www.ncbi.nlm.nih.gov/pubmed/29053641/
  6. Kosuth M, Mason SA, Wattenberg EV. Anthropogenic contamination of tap water, beer, and sea salt. PLoS One. 2018,13(4): e0194970. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5895013/
  7. Oehlmann J, Schulte-Oehlmann U, Kloas W et al.  A critical analysis of the biological impacts of plasticizers on wildlife. Philosophical Transactions of the Royal Society B. 2009;364:2047–2062. http://rstb.royalsocietypublishing.org/content/364/1526/2047
  8. Thompson RC, Moore CJ, vom Saal FS, Swan SH. Plastics, the environment and human health: Current consensus and future trends. Philosophical Transactions of the Royal Society B. 2009;364:2153–2166. https://royalsocietypublishing.org/doi/full/10.1098/rstb.2009.0053
  9. Thoms AW, Brosnana JT, Zidekb JM, Sorochana JC. Models for predicting surface temperatures on synthetic turf playing surfaces. Procedia Engineering. 2014;72:895-900. http://www.sciencedirect.com/science/article/pii/S1877705814006699
  10. Penn State’s Center for Sports Surface Research. Synthetic turf heat evaluation- progress report. 012. http://plantscience.psu.edu/research/centers/ssrc/documents/heat-progress-report.pdf
  11. Stier JC, Steinke K, Ervin EH, Higginson FR, McMaugh PE. Turfgrass benefits and issues. Turfgrass: Biology, Use, and Management, Agronomy Monograph 56. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America. 2013;105–145. https://dl.sciencesocieties.org/publications/books/tocs/agronomymonogra/turfgrassbiolog

National Center for Health Research Written Statement to Greenwich Board of Education

National Center for Health Research, February 19, 2020


Written Statement to Greenwich Board of Education

Diana Zuckerman, PhD, National Center for Health Research

February 19, 2020

Dear Chairman Bernstein and Members of the Greenwich Board of Education:

I am disappointed that I was unable to be there in person for your meeting on February 20, but I wanted to update you on the latest research about the health risks of artificial turf for children and adults.

As President of the National Center for Health Research, I want to share the information we have provided to Members of Congress, state and federal agencies, state and local legislators, parents, and others who want to ensure that our children are not exposed to dangerous chemicals or metals when they play on artificial turf or playgrounds. Our nonprofit think tank is located in Washington, D.C. Our scientists, physicians, and health experts conduct studies and scrutinize research. Our goal is to explain scientific and medical information that can be used to improve policies, programs, services, and products.

We commend you for considering the possible risks of replacing grass fields with artificial turf. In the last year, we’ve learned new information about lead and PFAS in artificial turf, as well as the risks of some of the newer infill materials that turf companies are using to replace tire crumb. Tire crumb has well-known risks, containing chemicals that have the potential to increase obesity; contribute to early puberty; cause attention problems such as ADHD; exacerbate asthma; and eventually cause cancer. However, the plastic grass itself has dangerous levels of lead, PFAS, and other toxic chemicals as well.  PFAS are of particular concern because they are “forever chemicals” that get into the human body and are not metabolized, accumulating over the years. Replacing tire waste with silica, zeolite, and other materials also has substantial risks.

Federal agencies such as the EPA and the U.S. Consumer Product Safety Commission have been investigating the safety of these products. Despite claims to the contrary, none have concluded that artificial turf is safe. Although the Trump Administration’s EPA stated that there was no conclusive evidence that the levels of chemicals in artificial turf was harmful to children, they made it clear that their research was based on assumptions rather than scientific research on children.

Lead

As you know, the American Academy of Pediatrics states that no level of lead exposure should be considered safe for children, because lead can cause cognitive damage even at low levels. Some children are more vulnerable than others, and that can be difficult or even impossible to predict. Since lead has been found in tire crumb as well as new synthetic rubber, it is not surprising that numerous artificial turf fields and playgrounds made with either tire crumb or “virgin” rubber have been found to contain lead. However, the Centers for Disease Control and Prevention (CDC) also warns that the “plastic grass” made with nylon or some other materials also contain lead. Whether from infill or from plastic grass, the lead doesn’t just stay on the surface. With wear, the turf materials turn to dust that is invisible to the eye but that children are breathing in when they play.

Why are chemicals that are banned from children’s toys allowed in artificial turf and rubber playground surfaces?

Synthetic rubber and plastic are made with different types of endocrine (hormone) disrupting chemicals (also called EDCs). There is very good evidence regarding these chemicals in tire crumb, based on studies done at Yale and by the California Office of Environmental Health Hazard Assessment (OEHHA).[1]

A 2018 report by Yale scientists detected 92 chemicals in samples from 6 different artificial turf companies, including unused bags of tire crumb. Unfortunately, the health risks of most of these chemicals had never been studied. However, 20% of the chemicals that had been tested are classified as probable carcinogens and 40% are irritants that can cause asthma or other breathing problems, or can irritate skin or eyes.[2]

There are numerous studies indicating that endocrine-disrupting chemicals found in rubber and plastic cause serious health problems. Scientists at the National Institute of Environmental Health Sciences (which is part of NIH) have concluded that unlike most other chemicals, hormone-disrupting chemicals can be dangerous at very low levels, and the exposures can also be dangerous when they combine with other exposures in our environment. 

That is why the Consumer Product Safety Commission has banned numerous endocrine-disrupting chemicals from toys and products used by children. The products involved, such as pacifiers and teething toys, are banned even though they would result in very short-term exposures compared to artificial turf or playground surfaces.

A report warning about possible harm to people who are exposed to rubber and other hormone disrupting chemicals at work explains that these chemicals “can mimic or block hormones and disrupt the body’s normal function, resulting in the potential for numerous health effects. Similar to hormones, EDC can function at very low doses in a tissue-specific manner and may exert non-traditional dose–response because of the complicated dynamics of hormone receptor occupancy and saturation.”[3]

Studies are beginning to demonstrate the contribution of skin exposure to the development of respiratory sensitization and altered pulmonary function. Not only does skin exposure have the potential to contribute to total body burden of a chemical, but also the skin is a highly biologically active organ capable of chemical metabolism and the initiation of a cascade of immunological events, potentially leading to adverse outcomes in other organ systems.

Scientific Evidence of Cancer and Other Systemic Harm

It is essential to distinguish between evidence of harm and evidence of safety. Like the Trump Administration’s EPA, companies that sell and install artificial turf often claim there is “no evidence children are harmed” or “no evidence that the fields cause cancer.” This is often misunderstood as meaning the products are safe or are proven to not cause harm. Neither is true.

It is true that there no clear evidence that an artificial turf field has caused specific children to develop cancer. However, the statement is misleading because it is virtually impossible to prove any chemical exposure causes one specific individual to develop cancer.

As an epidemiologist, I can also tell you that for decades there was no evidence that smoking or Agent Orange caused cancer. It took many years to develop that evidence, and the same will be true for artificial turf. 

I have testified about the risks of these materials at the U.S. Consumer Product Safety Commission as well as state legislatures and city councils. I am sorry to say that I have repeatedly seen and heard scientists paid by the turf industry and other turf industry lobbyists say things that are absolutely false. They claim that these products are proven safe (not true) and that federal agencies have stated there are no health risks (also not true). 

However, we know that the materials being used in artificial turf and rubber playground surfaces contain carcinogens, and when children are exposed to those carcinogens day after day, week after week, and year after year, they increase the chances of our children developing cancer, either in the next few years or later as adults. That should be adequate reason not to install them in your community. That’s why I have spoken out about the risks of artificial turf in my community and on a national level. The question must be asked: if they had all the facts, would Greenwich or any other community choose to spend millions of dollars on fields that are less safe than well-designed natural grass fields?

Dangerously Hot and Hard Fields

I lived in Connecticut for several years while on the faculty at Yale and Vassar, and I know the climate well. When the weather is warm and/or sunny, it is usually quite pleasant to be outside – as long as you aren’t on artificial turf or an outdoor rubber surface. Even when the temperature above the grass is 80 degrees Fahrenheit, artificial turf can reach 150 degrees or higher. Obviously, a 90 degree day is likely to be even hotter than 150 degrees on turf. That can cause “heat poisoning” as well as burns.

Artificial turf fields get hard as well. Turf companies recommend annual tests at 10 locations on each turf field, using something called a Gmax scores. A Gmax score over 200 is considered extremely dangerous and is considered by industry to pose a death risk. However, the synthetic turf industry and ASTM (American Society for Testing and Materials), suggest scores should be even lower — below 165 to ensure safety comparable to a grass field. Is Greenwich paying to have these tests conducted on all your public artificial turf fields?

The hardness of natural grass fields is substantially influenced by rain and other weather; if the field gets hard, rain or watering will make it safe again. In contrast, once an artificial turf field has a Gmax score above 165, it needs to be replaced because while the scores can vary somewhat due to weather, the scores will inevitably get higher because the turf will get harder. Gmax testing involves testing 10 different areas of a playing fields, to make sure all are considered safe.  Some officials average those 10 scores to determine safety; however, experts explain that is not appropriate. If a child (or adult) falls, it can be at the hardest part of the field, which is why that is the way safety is determined.

Environmental Issues

In addition to the health risks to school children and athletes, approximately three tons of infill materials migrate off of each synthetic turf field into the greater environment each year. About 2-5 metric tons of infill must be replaced every year for each field, meaning that tons of the infill have migrated off the field into grass, water, and our homes.[4] The fields also continuously shed microplastics as the plastic blades break down.[5,6] These materials may contain additives such as PAHs, flame retardants, UV inhibitors, etc., which can be toxic to marine and aquatic life; and microplastics are known to migrate into the oceans, food chain, and drinking water and can absorb and concentrate other toxins from the environment.[7,8,9]

Synthetic surfaces also create heat islands.10,11 In contrast, organically managed natural grass saves energy by dissipating heat, cooling the air, and reducing energy to cool nearby buildings. Natural grass and soil protect groundwater quality, biodegrade polluting chemicals and bacteria, reduce surface water runoff, and abate noise and reduce glare.[12]

Envirofill and Alternative Infills

Envirofill artificial turf fields are advertised as “cooler” and safer, but our research indicates that these fields are still at least 30-50 degrees hotter than natural grass. Envirofill is composed of materials resembling plastic polymer pellets (similar in appearance to tic tacs) with silica inside. Silica is classified as a hazardous material according to OSHA regulations, and the American Academy of Pediatrics specifically recommends avoiding it on playgrounds. The manufacturers and vendors of these products claim that the silica stays inside the plastic coating. However, sunlight and the grinding force from playing on the field breaks down the plastic coating. For that reason, even the product warranty admits that only 70% of the silica will remain encapsulated. The other 30% can be very harmful as children are exposed to it in the air. 

In addition, the Envirofill pellets have been coated with an antibacterial called triclosan. Triclosan is registered as a pesticide with the EPA and the FDA has banned triclosan from soaps because manufacturers were not able to prove that it is safe for long-term use. Research shows a link to liver and inhalation toxicity and hormone disruption. The manufacturer of Envirofill says that the company no longer uses triclosan, but they provide no scientific evidence that the antibacterial they are now using is any safer than triclosan. Microscopic particles of this synthetic turf infill will be inhaled by children, and visible and invisible particles come off of the field, ending up in shoes, socks, pockets, and hair.

In response to the concerns of educated parents and government officials, other new materials are now being used instead of tire crumb and other very controversial materials. However, all the materials being used (such as volcanic ash, corn husks, and Corkonut) have raised concerns and none are proven to be as safe or effective as well-designed grass fields. 

Conclusions

There have never been any safety tests required prior to sale that prove that any artificial turf products are safe for children who play on them regularly. In many cases, the materials used are not publicly disclosed, making independent research difficult to conduct. None of these products are proven to be as safe as natural grass in well-constructed fields. 

I have cited several relevant scientific articles on artificial turf in this letter, and there are numerous studies and growing evidence of the harm caused by these synthetic materials. I would be happy to provide additional information upon request (dz@center4research.org).

I am not paid to write this statement. I am one of the many parents and scientists who are very concerned about the impact of artificial fields on our children. Last year, I told members of the BET that their decision about artificial turf can save lives and improve the health of children in Greenwich.  You owe it to your community to make sure you know the risks of artificial turf and do all you can to protect Greenwich children from the known risks and also the suspected risks.  Because of Greenwich’s reputation as a well-educated and affluent community, your decisions about artificial turf in Greenwich will be cited by other communities, making it even more important that your decision is based on scientific evidence, not on sales pitches by individuals with conflicts of interest.

Officials in communities all over the country have been misled by artificial turf salespeople. They were erroneously told that these products are safe. But on the contrary, there is clear scientific evidence that these materials are harmful. The only question is how much exposure is likely to be harmful to which children? We should not be willing to take such a risk. Our children deserve better.

Sincerely,

Diana Zuckerman, Ph.D.

President

The PDF of this letter can be found here.

References

  1. 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 
  2. 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;229:64. https://doi.org/10.1007/s11270-018-3711-7 
  3. Anderson SE and Meade BJ. Potential Health Effects Associated with Dermal Exposure to Occupational Chemicals. Environmental Health Insights. 2014; 8(Suppl 1):51–62. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270264/
  4. York T. Greener grass awaits: Environmental & fiscal responsibility team up in synthetic turf. Recreation Management. February 2012. http://recmanagement.com/feature_print.php?fid=201202fe02
  5. Magnusson K, Eliasson K, Fråne A, et al. Swedish sources and pathways for microplastics to the marine environment, a review of existing data. Stockholm: IVL- Swedish Environmental Research Institute. 2016. https://www.naturvardsverket.se/upload/miljoarbete-i-samhallet/miljoarbete-i-sverige/regeringsuppdrag/utslapp-mikroplaster-havet/RU-mikroplaster-english-5-april-2017.pdf
  6. Kole PJ, Löhr AJ, Van Belleghem FGAJ, Ragas AMJ. Wear and tear of tyres: A stealthy source of microplastics in the environment. International Journal of Environmental Research Public Health. 2017;14(10):pii: E1265. https://www.ncbi.nlm.nih.gov/pubmed/29053641/
  7. Kosuth M, Mason SA, Wattenberg EV. Anthropogenic contamination of tap water, beer, and sea salt. PLoS One. 2018,13(4): e0194970. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5895013/
  8. Oehlmann J, Schulte-Oehlmann U, Kloas W et al.  A critical analysis of the biological impacts of plasticizers on wildlife. Philosophical Transactions of the Royal Society B. 2009;364:2047–2062. http://rstb.royalsocietypublishing.org/content/364/1526/2047
  9. Thompson RC, Moore CJ, vom Saal FS, Swan SH. Plastics, the environment and human health: Current consensus and future trends. Philosophical Transactions of the Royal Society B. 2009;364:2153–2166. https://royalsocietypublishing.org/doi/full/10.1098/rstb.2009.0053
  10. Thoms AW, Brosnana JT, Zidekb JM, Sorochana JC. Models for predicting surface temperatures on synthetic turf playing surfaces. Procedia Engineering. 2014;72:895-900. http://www.sciencedirect.com/science/article/pii/S1877705814006699
  11. Penn State’s Center for Sports Surface Research. Synthetic turf heat evaluation- progress report. 012. http://plantscience.psu.edu/research/centers/ssrc/documents/heat-progress-report.pdf
  12. Stier JC, Steinke K, Ervin EH, Higginson FR, McMaugh PE. Turfgrass benefits and issues. Turfgrass: Biology, Use, and Management, Agronomy Monograph 56. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America. 2013;105–145. https://dl.sciencesocieties.org/publications/books/tocs/agronomymonogra/turfgrassbiolog

NCHR Letter to Mayor Cohn and Members of the Rye City Council Concerning the Health Risks of Artificial Turf and Playgrounds

National Center for Health Research, November 18, 2019


Download the letter here.

Dear Mayor Cohn and Members of the City Council:

Residents of Rye reached out to me to obtain my expertise in assessing the validity of the articles and letters provided by Stantec Design Services, regarding the health risks of installing artificial turf at what is now Nursery Field.   I am providing this information pro bono because our nonprofit research center is very concerned about the misleading information that has been presented to Rye officials regarding artificial turf.

The purpose of this letter is to focus on the research literature summarized and presented in Stantec’s review, including those in their Appendix.  It will not be focused on the logistical issues, but rather the health issues of importance to children using the field, and those who would be exposed to the chemicals in artificial turf because of its location near homes, wetlands, and a main tributary to Long Island Sound.

I will focus first on the claims that artificial turf does not cause cancer.  Dr. Archie Bleyer, quoted by Stantec, has impressive credentials, but his conclusions are based on his expertise regarding decades-old research while ignoring many of the most recent published studies.  Most important, as city officials, it is essential to distinguish between the lack of conclusive research linking artificial turf to cancer, and the often-made claim by the turf industry that artificial turf does not cause cancer.  The lack of conclusive proof of danger is not equal to proof of safety.  It is widely known that artificial turf contains chemicals that are probable and known carcinogens.   However, it takes years for cancer to develop after exposure to carcinogens.  For example, most smokers start smoking as teenagers but they don’t develop lung cancer for at least 3-4 decades. The reports of cancer clusters, such as the one among soccer players in Washington state, are the first hint that exposure to the chemicals contained in artificial turf increase the risk of cancer, but this too takes years to conclusively determine whether the cancer risk is higher due to the exposure.  That is one of the reasons why cancer clusters, such as the one reported in Washington State, can rarely determine causality.  It reminds me of cancer clusters among Vietnam veterans exposed to Agent Orange that were considered just a fluke until years later, when researchers concluded that Agent Orange caused certain types of cancer.  While we wait for this research, we cannot accurately conclude that there is no risk. Instead, we can only state that we do not know the level of risk.

Equally important, cancer is not the only health risk associated with the use of artificial turf.  The rubber pieces break down into very small pieces called particulate matter, which are kicked up into the air when the field is used where they can be inhaled.  The particulate matter can aggravate asthma, and can contain irritants and heavy metals.  The research cited by Stantec ignores that serious issue.

In addition, as the field gets hot, which can be 50-80 degrees hotter than the air or natural grass, the heat can cause heat stroke and even cause burns.  The highest temperature we have tested on a summer day in the 90’s was over 180 degrees.  In addition, heat from the fields makes it more likely that the chemicals are released into the air.  These can include polycyclic aromatic hydrocarbons (PAHs), and endocrine disruptors such as phthalates. These exposures can contribute to obesity, early puberty, ADHD, and eventually cancer.  Children are more vulnerable to these exposures than adults.

The Massachusetts HHS letter from 2015 and the letter from the State of Connecticut from 2015 both attempt to summarize information that focuses on cancer data but is broader than the cancer risk of artificial turf.  However, the studies quoted in the letter are small and so their generalizability to other fields is limited.  Importantly, it excluded several studies that raised concerns about the risks posed by artificial turf and pre-dates several more recent studies that have raised serious health concerns.

This year, testing in several communities found dangerous levels of lead in artificial turf as well as playgrounds made from synthetic rubber.  For example, testing of playgrounds and artificial turf fields in affluent and lower-income communities in Washington, D.C. resulted in more than 2 dozen that were closed due to health risks (see signs below).

Sign on artificial turf field stating that the field failed an "impact attenuation" or "hardness" test, which means that there is an increased risk of injury in the event of a fall.Sign - Warning: Do not eat infill mix in artificial turf as it may be harmful to your health

In the below left photo, children are playing on an artificial turf field near their school; tire crumb infill that had been hidden in the plastic grass came to the surface due to rain and wind.

Children playing in tire crumb infill from field

Used artificial turf with trash in the dumpster

The environmental implications of artificial turf are also important.  In the above right photo, you can see old turf has been dumped in a dumpster with trash. Much of the infill has already spread to the nearby playground, grass, and stream.

I will now focus on just a few of the studies that were not discussed in the letters submitted by Stantec, all of which demonstrate the very serious, evidence-based concerns about health risks, in chronological order:

Shalat 2011 (for the New Jersey Department of Environmental Protection) – They 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.  The study found that there was more inhalable particulate matter in the air around a moving object (either a robot or 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 inhalable particulate matter to get into the air where it can be harmful.  The study also found that the oldest field studied (8 years old) had more inhalable particulate matter than younger fields in this study (1–3 years old).  This is especially worrisome because the dust contains lead.  The authors state, “While it is not possible to draw broad conclusions from this limited sample of fields, 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.  It also would appear likely from this sample that if the lead is present to any appreciable extent in the wipes it will likely be present in the breathing zone of players who are active on these fields, and that furthermore, these levels potentially exceed ambient EPA standards.”  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.”[1]

Llompart et al 2013 (Universidad de Santiago de Compostela) – This study examined samples from 9 playgrounds and 7 newly purchased rubber floor tiles that were made from recycled tire rubber in Spain.  It found all samples released hazardous chemicals into the air, where they can be inhaled, some of which were at high or very high levels. PAHs were found in all samples, including the carcinogenic B[a]P.  Other chemicals of concern include the phthalates DEP, DIBP, DBP, DEHP, and BHT.  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.”[2]

Marsili et al 2014 (Siena University) – This study evaluated the recycled rubber infill (4 samples were not yet installed and 4 from fields that were 1-8 years old) and 1 new sample from virgin rubber in Italy. 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.”[3]

Canepari et al 2016 (Sapienza University of Rome) – This study examined particulate matter and extractable chemicals from 1 sample of recycled tire rubber, 2 new and a single 7-year-old sample of natural rubber, and 1 sample of last-generation thermoplastic elastomer crumb (TPE).  The recycled tire rubber had a larger 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.”[4]

Celeiro et al 2018 (Universidad de Santiago de Compostela) – This study evaluated the amount of chemicals released into the air from samples of recycled tire rubber infill from 15 soccer fields in Spain.  Analysis 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 could leach into runoff. “The environmental and health risks derived from the use of these surfaces have to be considered and some regulations should be adopted.”[5]

Benoit and Demars 2018 (Yale University) – This study analyzed 9 bags of recycled tire mulch from chain stores and 6 samples of recycled tire infill for athletic fields.  It focused on the chemicals which people using the fields would be expected to be exposed to, and found 92 chemical compounds.  Only about half of these compounds have been tested for effects on human health, of which 9 are carcinogens and 20 are irritants.  They concluded, “But what is known is 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.”[6]

Perkins et al 2019 (Yale University) – Based on previously published research, the researchers identified 306 chemicals found in crumb rubber. 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.”[7]

The bottom line:  There is a growing body of evidence of the risks of the chemicals and lead in artificial turf and rubber surface playgrounds.  It would not be ethical to intentionally expose children to these play areas, and no independent researchers or government researchers have conducted long-term studies to determine if children with greater exposures are more likely to develop the health problems that are expected, such as obesity, asthma, cognitive damage, early puberty, and eventually cancer.

Please contact me with any questions at (202) 223-4000 or dz@center4research.org .

Sincerely,

Diana Zuckerman, Ph.D.
President

References

  1. 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
  2. Llompart M, Sanchez-Prado L, Pablo Lamas J, et al. Hazardous Organic Chemicals in Rubber Recycled Tire Playgrounds and Pavers. Chemosphere. 2013;90(2):423-431. https://doi.org/10.1016/j.chemosphere.2012.07.053
  3. 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
  4. 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
  5. 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
  6. 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;229:64. https://doi.org/10.1007/s11270-018-3711-7
  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/

NCHR Letter to Mayor Cohn and Members of the Rye City Council Concerning Artificial Turf and Playgrounds

National Center for Health Research, October 16th, 2019


Dear Mayor Cohn and Members of the Rye City Council:

I am writing on behalf of the National Center for Health Research.  Our nonprofit think tank is located in Washington, D.C. Our scientists, physicians, and health experts conduct studies and scrutinize research. Our goal is to explain scientific and medical information that can be used to improve policies, programs, services, and products.   We have been contacted by families in Rye who are concerned about the risks of artificial turf and playgrounds. We are impressed with their knowledge and agree with them that converting grass fields to artificial turf poses unnecessary dangers to children in your community.

As a scientist who has worked on health policy issues for more than 30 years, I don’t shock easily.  However, it is shocking and disturbing that artificial turf athletic fields and playgrounds are exposing children on a daily basis to chemicals and materials that are known to have the potential to increase obesity; contribute to early puberty; cause attention problems such as ADHD; harbor deadly bacteria; exacerbate asthma; and eventually cause cancer.

Federal agencies such as the EPA and the U.S. Consumer Product Safety Commission have been investigating the safety of these products. A recently released EPA report found toxic chemicals in artificial turf, but did not evaluate whether or not the level of exposure would harm children.  Despite claims to the contrary, no federal agency has concluded that artificial turf is safe.

Scientific Evidence of Cancer and Other Systemic Harm

First, it is important to distinguish between evidence of harm and evidence of safety.  Companies that sell and install artificial turf often claim there is “no evidence that children are harmed” or “no evidence that the fields cause cancer.”  This is often misunderstood as meaning the products are safe or are proven to not cause harm. Neither is true.

The artificial turf industry will tell you there is no clear evidence that their fields caused any child to develop cancer.  That is true, but the statement is misleading because it is virtually impossible to prove any chemical exposure causes one specific individual to develop cancer.

As an epidemiologist, I can also tell you that for decades there was no evidence that smoking or Agent Orange caused cancer. It took many years to develop that evidence, and the same will be true for artificial turf.

I have testified about the risks of these materials at the U.S. Consumer Product Safety Commission as well as state legislatures and city councils. I am sorry to say that I have repeatedly seen and heard scientists paid by the turf industry and other turf industry lobbyists say things that are absolutely false. They claim that these products are proven safe (not true) and that federal agencies have stated there are no health risks (also not true).

Most research has focused on the risks of infill made from recycled tire waste. However, recent research has indicated the presence of dangerous levels of chemicals in the plastic blades of grass as well as in the tire waste. So, even if the infill is replaced with a safer materials, the plastic grass carpet itself is dangerous.

We know that the materials being used contain carcinogens, and when children are exposed to those carcinogens day after day, week after week, and year after year, they increase the chances of our children developing cancer, either in the next few years or later as adults. That should be adequate reason not to install them in your community. That’s why I have spoken out about the risks of artificial turf in my community and on a national level. The question must be asked: if they had all the facts, would Rye or any other community choose to spend millions of dollars on fields that are less safe than well-designed natural grass fields?

Synthetic rubber and plastic are made with different types of endocrine (hormone) disrupting chemicals as well as carcinogens.  There is very good evidence regarding these chemicals in tire crumb, based on studies done at Yale and by the California Office of Environmental Health Hazard Assessment (OEHHA). [1]

A 2015 report by Yale scientists detected 96 chemicals in samples from 5 different artificial turf companies, including unused bags of tire crumb. Unfortunately, the health risks of most of these chemicals had never been studied.  However, 20% of the chemicals that had been tested are classified as probable carcinogens and 40% are irritants that can cause asthma or other breathing problems, or can irritate skin or eyes. [2]

There are numerous studies on the impact of hormone-disrupting chemicals (also called endocrine disrupting chemicals or EDCs), and the evidence is clear that these chemicals found in rubber and plastic cause serious health problems.  Scientists at the National Institute of Environmental Health Sciences (which is part of NIH) have concluded that unlike most other chemicals, hormone-disrupting chemicals can be dangerous at very low levels, and the exposures can also be dangerous when they combine with other exposures in our environment.

That is why the Consumer Product Safety Commission has banned numerous endocrine-disrupting chemicals from toys and products used by children. The products involved, such as pacifiers and teething toys, have been banned for more than a decade, even though they would result in very short-term exposures compared to artificial turf.

A report warning about possible harm to people who are exposed to rubber and other hormone disrupting chemicals at work explains that these chemicals “can mimic or block hormones and disrupt the body’s normal function, resulting in the potential for numerous health effects.  Similar to hormones, EDC can function at very low doses in a tissue-specific manner and may exert non-traditional dose–response because of the complicated dynamics of hormone receptor occupancy and saturation.”[3]

Studies are beginning to demonstrate the contribution of skin exposure to the development of respiratory sensitization and altered pulmonary function. Not only does skin exposure have the potential to contribute to total body burden of a chemical, but also the skin is a highly biologically active organ capable of chemical metabolism and the initiation of a cascade of immunological events, potentially leading to adverse outcomes in other organ systems.

Envirofill and Alternative Infills

Artificial turf fields are often 50-70 degrees hotter (or more) compared to grass fields, and this can be dangerous for children on a warm day.  Envirofill artificial turf fields is advertised as “cooler” and safer than tire crumb, but our research indicates that these fields are still at least 30-50 degrees hotter than natural grass.  Envirofill is composed of materials resembling plastic polymer pellets (similar in appearance to tic tacs) with silica inside.  Silica is classified as a hazardous material according to OSHA regulations, and the American Academy of Pediatrics specifically recommends avoiding it on playgrounds. The manufacturers and vendors of these products claim that the silica stays inside the plastic coating.  However, sunlight and the grinding force from playing on the field breaks down the plastic coating.   For that reason, even the product warranty admits that only 70% of the silica will remain encapsulated.  The other 30% can be very harmful as children are exposed to it in the air.

In addition, the Envirofill pellets have been coated with an antibacterial called triclosan.  Triclosan is registered as a pesticide with the EPA and the FDA has banned triclosan from soaps because manufacturers were not able to prove that it is safe for long-term use.  Research shows a link to liver and inhalation toxicity and hormone disruption.  The manufacturer of Envirofill says that the company no longer uses triclosan, but they provide no scientific evidence that the antibacterial they are now using is any safer than triclosan.  Microscopic particles of this synthetic turf infill will be inhaled by children, and visible and invisible particles come off of the field, ending up in shoes, socks, pockets, and hair.

In response to the concerns of educated parents and government officials, other new materials are now being used instead of tire crumb and other very controversial materials.  However, all the materials being used (such as volcanic rock, corn husks, and Corkonut) have raised concerns and none are proven to be as safe or effective as well-designed grass fields.  And as noted above, the plastic grass itself is made from dangerous chemicals.

Dangerously Hard Fields, Turf Burns, and Hot Fields

I want to briefly mention safety issues pertaining to Gmax scores.  A Gmax score measures how hard a field is, specifically regarding brain injuries.  A score over 200 is considered extremely dangerous and is considered by the synthetic turf industry to pose a death risk.  However, the synthetic turf industry and ASTM (American Society for Testing and Materials), suggest scores should be even lower — below 165 to ensure safety comparable to a grass field.

The hardness of natural grass fields is substantially influenced by rain and other weather; if the field gets hard, rain or watering will make it safe again.  In contrast, once an artificial turf field has a Gmax score above 165, it needs to be replaced because while the scores can vary somewhat due to weather, the scores will inevitably get higher because the turf will get harder.  Gmax testing involves testing 10 different areas of a playing fields, and some officials average those 10 scores to determine safety.  However, experts explain that is not appropriate.  If a child (or adult) falls, it can be at the hardest part of the field, which is why that is the way safety is determined.

In addition to hard fields, artificial turf is more likely to cause “turf burns” which can be very painful and can get infected.  There is a good reason why almost all professional baseball parks use grass rather than artificial turf, and why professional football and soccer teams also prefer natural grass.

In addition to the health risks to school children and athletes, approximately three tons of infill materials migrate off of each synthetic turf field into the greater environment each year.  About 2-5 metric tons of infill must be replaced every year for each field, meaning that tons of the infill have migrated off the field into grass, water, and our homes.[4] The fields also continuously shed microplastics as the plastic blades break down.[5,6] These materials may contain additives such as PAHs, flame retardants, UV inhibitors, etc., which can be toxic to marine and aquatic life; and microplastics are known to migrate into the oceans, food chain, and drinking water and can absorb and concentrate other toxins from the environment. [7,8,9]

As noted above, artificial turf gets much hotter than grass, and so does the air above it.  Synthetic surfaces create heat islands. [10,11] In contrast, organically managed natural grass saves energy by dissipating heat, cooling the air, and reducing energy to cool nearby buildings.  Natural grass and soil protect groundwater quality, biodegrade polluting chemicals and bacteria, reduce surface water runoff, and abate noise and reduce glare. [12]

Conclusions

There are currently no safety tests required prior to sale that prove that any artificial turf products are safe.  In many cases, the materials used are not made public, making independent research difficult to conduct. None of these products are proven to be as safe as natural grass in well-constructed fields.

I have cited several relevant scientific articles on artificial turf in this letter, and I can attest to the fact there are numerous studies and growing evidence of the harm caused by these synthetic materials. I would be happy to provide additional information upon request (dz@center4research.org or 202 223-4000).

I am not paid to write this statement. I am one of the many parents and scientists who are very concerned about the impact of artificial fields on our children.  Your decision about artificial turf can save lives and improve the health of children in Rye and will serve as a model to other communities.

Officials in communities all over the country have been misled by artificial turf salespeople. They were erroneously told that these products are safe.  But on the contrary, there is clear scientific evidence that these materials are potentially harmful. The only question is how harmful and how much exposure is likely to be harmful?  We should not be willing to take such a risk. Our children deserve better.

Sincerely,

Diana Zuckerman, PhD
President

 

References

  1. 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
  2. Yale Study Reveals Carcinogens and Skin Irritants in Synthetic Turf. http://wtnh.com/2015/09/03/new-yale-study-reveals-carcinogens-and-skin-irritants-in-synthetic-turf/
  3. Anderson SE and Meade BJ, Potential Health Effects Associated with Dermal Exposure to Occupational Chemicals, Environ Health Insights. 2014; 8(Suppl 1): pgs 51–62. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270264/
  4. York T. Greener grass awaits: Environmental & fiscal responsibility team up in synthetic turf. Recreation Management. February 2012. http://recmanagement.com/feature_print.php?fid=201202fe02.
  5. Magnusson K, Eliasson K, Fråne A, et al. Swedish sources and pathways for microplastics to the marine environment, a review of existing data. Stockholm: IVL- Swedish Environmental Research Institute. 2016. https://www.naturvardsverket.se/upload/miljoarbete-i-samhallet/miljoarbete-i-sverige/regeringsuppdrag/utslapp-mikroplaster-havet/RU-mikroplaster-english-5-april-2017.pdf
  6. Kole PJ, Löhr AJ, Van Belleghem FGAJ, Ragas AMJ. Wear and tear of tyres: A stealthy source of microplastics in the environment. Int J Environ Res Public Health. 2017 14(10). pii: E1265. https://www.ncbi.nlm.nih.gov/pubmed/29053641/
  7. Kosuth M, Mason SA, Wattenberg EV. Anthropogenic contamination of tap water, beer, and sea salt. PLoS One. 2018. 13(4): e0194970. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5895013/
  8. Oehlmann J, Schulte-Oehlmann U, Kloas W et al.  A critical analysis of the biological impacts of plasticizers on wildlife. Phil Trans R Soc B. 2009. 364: 2047–2062. http://rstb.royalsocietypublishing.org/content/364/1526/2047
  9. Thompson RC, Moore CJ, vom Saal FS, Swan SH. Plastics, the environment and human health: Current consensus and future trends. Philos Trans R Soc Lond B. 2009. 364: 2153–2166.
  10. Thoms AW, Brosnana JT, Zidekb JM, Sorochana JC. Models for predicting surface temperatures on synthetic turf playing surfaces. Procedia Engineering. 2014. 72: 895-900. http://www.sciencedirect.com/science/article/pii/S1877705814006699
  11. Penn State’s Center for Sports Surface Research. Synthetic turf heat evaluation- progress report. 012. http://plantscience.psu.edu/research/centers/ssrc/documents/heat-progress-report.pdf
  12. Stier JC, Steinke K, Ervin EH, Higginson FR, McMaugh PE. Turfgrass benefits and issues. Turfgrass: Biology, Use, and Management, Agronomy Monograph 56. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America. 2013. 105-145 https://dl.sciencesocieties.org/publications/books/tocs/agronomymonogra/turfgrassbiolog