Do You Know What Your Child Is Playing On?
An Overview of Playground Surface Materials
By Wendy Priesnitz
Playground surfaces are important. After all, kids can get badly hurt if they fall on concrete or
other paved surfaces. And, let’s face it, kids fall a lot, especially
when they’re playing on playground equipment or school and community
play fields. An estimated eighty percent of injuries on playgrounds are
as a result of falls. So it’s a good thing that many playgrounds provide
a surface that’s softer than pavement. Unfortunately, it appears not to
be such a good thing that some of those surfaces could be providing
health effects much worse than a skinned knee or even a broken arm.
Rubber mulch chips and rubber mats are
manufactured from recycled tires and sold as shock-absorbing materials
for playgrounds. The chips are also sold as garden mulch. Since tires
are made of vulcanized rubber, the mulch made from them is said by its
manufacturers to be virtually indestructible, so it won’t crumble or
However, in some jurisdictions, rubber tires are
classified as “hazardous waste” and can’t be disposed of without a
permit. That’s because tires contain a variety of toxins, including
carcinogens, chronic lung irritants, and endocrine disruptors. Various
studies have identified the chemicals found in tires, which are made of
forty to sixty percent rubber polymers, carbon black (twenty to
thirty-five percent), silicas, process and extender oils (up to
twenty-eight percent), vulcanization chemicals and chemical
antidegradents, plasticizers and softeners, and heavy metals.
In 2007, Environment and Human Health, Inc.
(EHHI) – a non-profit organization composed of doctors, public health
professionals, and policy experts – released a report about potentially
harmful exposures to recycled tire products used on playgrounds and
soccer fields. Informed by studies that found cancer in workers in
rubber fabrication and reclamation industries, EHHI undertook an
exploratory study with the Connecticut Agricultural Experiment Station
to examine what the materials were and whether they out-gassed harmful
chemicals into the air or were capable of leaching into ground water.
The four compounds confirmed to be found in the
Connecticut Agricultural Experiment Station study were: benzothiazole
(skin and eye irritant); butylated hydroxyanisole (carcinogen, endocrine
toxicant, immunotoxicant, neurotoxicant, and more); n-hexadecane (severe
irritant); and 4-(t-octyl) phenol (corrosive and destructive to mucous
membranes). And approximately two dozen other chemicals were found at
In a press statement at the time of the study,
David Brown, Sc.D., EHHI’s public health toxicologist, said, “Health
endpoints of concern are numerous. Some are acute irritation of the
lungs, skin, and eyes, and chronic irritation of the lungs, skin, and
eyes. However, knowledge is more limited about the effects of
semi-volatile chemicals on the kidney, endocrine system, nervous system,
cardiovascular system, immune system and development.”
Artificial or synthetic turf is manufactured from
polymers such as polypropylene or polyethylene. It was developed in the
mid-1960s by Monsanto under the name AstroTurf, and has since gained
widespread popularity as a replacement for grass. Originally used in
stadiums and on athletic fields for college and professional sports
teams, it now is also used in municipal parks, golf courses,
playgrounds, cruise ships, and airports. There is also a growing
residential market for artificial turf.
Artificial turf has some issues, including
overheating (as high as two hundred degrees) on hot days. It has also
been reported to increase ankle injuries and skin abrasions. It requires
the application of harmful disinfectants and sprays to reduce static
cling and odors. In the past, many synthetic turf companies used lead
paint to make the plastic blades of “grass” green, a practice that is
now thought to have been stopped after a series of lawsuits against the
But one of artificial turf’s biggest health
drawbacks is that many brands use a finer version of rubber mulch, also
made from ground up recycled tires – called “tire crumb” or “crumb
rubber” – as in-fill between the blades of “grass” to provide stability,
uniformity, and resiliency to the synthetic turf fields. Crumb rubber is
a pellet-like substance the size of a cracker crumb. It sheds dust that
can easily get into a person’s mouth, nose, shoes, and clothing. Many
public health organizations have concerns about the use of tire crumb in
Doctors from New York’s Mt. Sinai Children’s
Environmental Health Center have written: “Exposures to chemicals
present in crumb rubber at very high levels, typical of animal or
occupational studies, are known to cause birth defects, neurologic and
developmental deficits, and some can even cause cancer.”
David Brown, Sc.D., EHHI’s public health
toxicologist, says, “It is clear the recycled rubber crumbs are not
inert, nor is a high temperature or severe solvent extraction needed to
release metals, volatile organic compounds, or semi-volatile organic
compounds. The Connecticut Agricultural Experiment Station study
conclusively demonstrates that the tire crumbs and tire mulch release
chemical compounds into the air and ground water. Thus, tire crumbs
constitute a chemical exposure for humans and the environment.”
The California-based Center for Environmental
Health further points out that children are particularly vulnerable to
toxic threats: “Children have increased exposure to toxic chemicals due
to the unique way they interact with their environment. Because they are
growing and developing, their bodies are also more susceptible than
adults’ to chemical exposures.”
Unfortunately, children’s exposure to these
chemicals while using artificial turf fields has not been adequately
studied. The U.S. Environmental Protection Agency (EPA), in an
evaluation of its study of crumb rubber, determined that it was not
possible for the agency to reach “comprehensive conclusions without the
consideration of additional data.”
According to Dr. Joel Forman, an associate
professor of pediatrics and preventive medicine at New York's Mt. Sinai
Hospital, these data gaps make it difficult to draw firm conclusions. He
says, “None of [the studies] are long term, they rarely involve very
young children, and they only look for concentrations of chemicals and
compare it to some sort of standard for what’s considered acceptable.
That doesn’t really take into account subclinical effects, long-term
effects, the developing brain, and developing kids.”
The good news is that, in February 2016, the EPA, the Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry (ATSDR), and the U.S. Consumer Product Safety Commission (CPSC) launched a multi-agency action plan to study key environmental human health questions.
Meanwhile, some jurisdictions, like New York City and the
Los Angeles Unified School District, have removed crumb rubber from play
areas for young children, or are using alternatives in new
installations. The Center for Environmental Health recommends that
schools, when feasible, replace crumb rubber infill with natural
materials such as cork, coconut fibers, and even sand. In spite of these
concerns, which have been around for close to ten years and were
recently revived by an investigative report by NBC news, the industry
claims that research demonstrates no negative health effects from scrap
Aside from the possible health effects, in a 2007 report on the safety of rubber
playground chips, California officials found that nearly seventy percent
of rubber surfaces weren’t shock-absorbent enough to actually cushion
falls, possibly due to lack of maintenance. Wood chips were found, in
one study, to do a better job of protecting children from head trauma
than surfaces using recycled rubber.
Wood chips are natural and inexpensive; some
municipalities have them in abundance due to tree trimming. However, the
U.S. Department of Interior (DOI) has determined that ordinary wood
chips are not considered an accessible playground surface. In its place,
the International Play Equipment Manufacturers Association (IPEMA)
prefers Engineered Wood Fiber (EWF). This is wood ground to a fibrous
consistency, randomly sized but not typically over two inches in length.
The fibers knit together to provide a surface springy enough to cushion
falls, yet firm enough for wheelchairs, and they tend not to cause
splinters. Besides meeting ASTM International safety and accessibility
standards, EWF is a totally natural product and is not chemically
Sand and Pea Gravel
Grass is still found in some playgrounds. (And there can be problems with grass, too, if herbicides are used.)
However, research has found that impactable, absorbant materials, such
as sand or pea gravel, provide better protection than grassy surfaces,
with one study finding that risk of injury is reduced by 1.7 times when
playgrounds are surfaced with sand rather than grass.
Researchers at The Hospital for Sick Children and
York University, both in Toronto, have found that using granite sand as
playground surfacing reduced the risk of arm fractures, compared to wood
chip surfaces. The study published in 2009 in the open-access journal
PLoS Medicine, showed the risk of an arm fracture from a fall off
playground equipment was almost five times higher on a wood chip surface
compared to sand. Risks of other types of injuries were also higher on
However, playground designers don’t favor sand
because it hardens quickly, gets tracked into schools on students’
shoes, and attracts animals who use the play area like a litter box.
An alternative is pea gravel – smooth, round,
pea-sized stones that slide over each other’s surfaces to absorb shock.
It is relatively inexpensive, clean, doesn’t track into buildings
(especially important for school playgrounds), and drains well.
Whatever type of loose fill is used on a
playground, it should be present in sufficient quantities. The Canadian
Standards Council, which produces a nationally recognized standard for
playground safety, stipulates the material be used at a depth of at
least 15 cm (6 in) for preschool equipment and 30 cm (12 in) for
full-sized equipment. That means regular maintenance is almost as
important as the choice of material.
While we cannot and, I think, should not inhibit
our children’s free outdoor play by being fearful – or, worse, instilling
fear in them – we can ensure that the playgrounds they use are as safe
Helping Kids Play Safely
- Avoid tire crumb playgrounds in favor of wood
chip or grass sites.
- Use well-maintained playgrounds, because any
loose surface material can become scattered and thin, exposing your
child to a hardened, compressed surface.
- If you and your kids can’t avoid using
synthetic turf fields, remove the crumb rubber pellets from clothing,
bodies, and equipment after playing.
- Do not use synthetic turf on extremely hot
- Don’t let kids lie down or eat on a surface
that uses recycled tire rubber.
- Teach your children the importance of frequent
hand washing after playing.
- Lobby for the use of wood chips, EWF, pea
gravel, or sand surfaces rather than artificial turf or recycled rubber.
- Reduce the risk of falling by having children
use age-appropriate equipment.
- Avoid dressing children in scarves and
clothing with drawstrings or cords that could catch on playground
- Supervise very young children on playground
Wendy Priesnitz is Child's Play Magazine's editor. She
is a journalist with forty years of experience, the author of twelve
books about green living, natural parenting, and learning without
school, and the mother of two adult daughters.
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