NCHR Letter to the DC City Council on Artificial Turf

Dear Council Members,

I am writing to respond to the request for additional information from Councilwoman Cheh as follow-up to my statement and the written materials I provided at the October 13 roundtable on artificial turf.

As the president of the National Center for Health Research, I expressed my strong concerns about the safety of the synthetic turf that the city has used and is continuing to use.  As a scientist who has worked on health policy issues for more than 30 years, I don’t shock easily.  However, the fact that school athletic fields and playgrounds are exposing D.C. children on a daily basis to chemicals and materials that are known to increase obesity; contribute to early puberty; cause attention problems such as ADD; harbor deadly bacteria; and exacerbate asthma is very disturbing.  Surely these are exactly the types of health problems that the D.C. government should be doing its best to reduce, not increase.

Federal agencies were investigating the safety of these products during the Obama Administration and were close to completion when the Trump Administration took over the two federal agencies involved, the Environmental Protection Agency and the Consumer Product Safety Commission.  Despite claims to the contrary at the October roundtable, neither agency has concluded that artificial turf is safe.  However, it is clear that we can’t depend on the Trump Administration to scrutinize the science regarding these products in a way that will be credible, and that means more work for the rest of us who care about children’s safety.

Envirofill and Other Hot Artificial Turf

As noted at the roundtable, all types of turf have risks and benefits, including natural grass.  However, some materials are well known to have substantial risks.  For example, DCPS is installed synthetic turf with Envirofill at Janney Elementary.  Although it is advertised as “cooler” and safer than older types of artificial turf, on a recent 64 degree afternoon, the temperature at the new Janney Envirofill field was 136 degrees, compared to 89 degrees on the grass.  And 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 is contained 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; here’s a screen grab from a November 2016 Patriots vs. Seahawks game, which shows how the silica sand infill is kicked up when players dive on a synthetic surface with silica sand infill.

In addition, the Envirofill pellets are coated with an antibacterial called Microban, which is a trade name for triclosan.  Triclosan is registered as a pesticide with the EPA and last year the FDA banned triclosan from soaps because manufacturers were not able to prove that it is safe for long-term use, since research shows a link to liver and inhalation toxicity and hormone disruption.  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.

I recently gave a guest lecture at a local college and when I asked if anyone had experience with artificial turf, two young women had stories to share.  They described playing on an artificial turf field on a sunny day, where they could actually see the heat waves rising off the field that had a strong chemical odor.

Councilwoman Cheh asked me to provide scientific evidence to back up my statements.  In addition to the links provided above regarding triclosan and silica, I want to describe the data regarding carcinogens and hormone disrupting chemicals that can cause obesity, early puberty, and attention deficits.

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 that there is “no evidence that children are harmed” or “no evidence that the fields cause cancer.”  That is often misunderstood as meaning that the products are safe or are proven to not cause harm. Neither is true.

It took decades to prove that smoking can cause cancer, a fact that everyone now agrees is true.  As each type of artificial turf is replaced by a new type of artificial turf, it will be equally difficult to prove that these different types of fields cause specific children to develop cancer, obesity, early puberty, or ADD.  For that reason, we need to focus on what is known about the materials the fields are made of and what the implications are for children’s health.

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).  The latter conducted three laboratory studies to investigate the potential health risks to children from playground surfaces made from recycled tires. One study evaluated the level of chemicals released and the other two studies looked at the risk of injury from falls.

The OEHHA studies showed that the children would be exposed to five chemicals, including four PAHs, one of which, chrysene,” was high enough to possibly increase the chances of a child developing cancer.[1]

Out of the 32 playgrounds studied, only 10 met that state’s standard for “head impact safety” to reduce brain injury and other serious harm in children who fall while playing. All five surfaces made of wood chips met the safety standard.[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]

Less is known about the materials that are used in PIP and other rubber products; some are recycled tire materials and some are “virgin rubber” but all are made from synthetic rubber, which is a petroleum based product.  This week I visited a playground at Chevy Chase Recreation Center.  Although the playground seems to be a relatively new solid rubber surface, there are several areas that are already broken, with dark crumb rubber and other very small colorful particles clearly showing. Some of the particles look like they could be from plants, but you can’t crush or tear them as you can with plant material.  Children can pick up those particles intentionally or unintentionally; little children are likely to eat it or get it in their mouths, shoes, or clothes, and children of any age will certainly get it on their skin.  As noted above, the evidence is clear that these rubber particles are dangerous.

Rather than provide a lengthy description of all the studies showing the impact of hormone-disrupting chemicals (also called endocrine disrupting chemicals or EDCs), I will assume you know that the evidence is clear about those chemicals being in rubber and plastic and causing health problems.  Scientists at the NIH environmental institute, which is called the National Institute of Environmental Health Sciences, have concluded that unlike most other chemicals,  hormone-disrupting chemicals can be dangerous at very low levels as well as at higher levels, and the exposures can be even more 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 ages 3 and younger.  Like playgrounds and artificial turf fields, these products were sold in the U.S. for many years prior to the ban, because the companies were not required to prove that the products were safe.

Instead of focusing on those studies, here is just one recent scientific study on the health risks of synthetic rubber.  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]

That article lists numerous EDCs found in rubber products and warns that “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.”

Dangers of Hard Fields and Playgrounds

I want to briefly mention safety issues pertaining to Gmax scores.  As you know, a Gmax score over 200 is considered extremely dangerous and is considered by industry to pose a death risk.  The synthetic turf industry and ASTM suggest that scores should be below 165 to ensure safety comparable to a grass field.  At the roundtable it was mentioned that grass fields can also get extremely hard, which is true.  However, 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.  Moreover, averaging Gmax scores for a field is an inappropriate way to determine safety.  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.


I have appreciated the opportunity to meet with several Councilmembers’ staff and I commend the Council for banning crumb rubber during FY 2018.  Unfortunately, however, Envirofill, “poured in place” rubber (PIP), EPDM, and all the other synthetic materials currently on the market all have petroleum based materials and therefore share some of the same health risks.  While the companies that sell these products claim they are safe and meet federal safety standards, there are currently no federal safety tests required to prove that these products are safe.  In many cases, the materials used are not public, making independent research difficult to conduct. None of these products are proven to be as safe as natural grass in well-constructed fields such as the Maryland Soccerplex. Although a well-respected grass expert offered a free consultation on how to install well-engineered grass designed to withstand rain and play, DGS did not respond to his offer.

I have also attached an annotated bibliography of numerous relevant scientific articles on artificial turf that will help you see that there is growing evidence of the harm of these synthetic materials on fields and playgrounds.  This is just a sample of studies, and there are many more, so let me know if you’d like additional information.

I am one of many parents and scientists in D.C. that are very concerned about the impact of these artificial fields and playgrounds on our children.  It is clear that city officials have assumed these products are safe because the salespeople told them they were safe.  Unfortunately, there is clear scientific evidence that these materials are potentially harmful, and the only question is how harmful are they and how much exposure is likely to be harmful?  Our children deserve better.


Diana Zuckerman, PhD


  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. 
  2. 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.