Dear Santa Clara Board of Supervisors and the Santa Clara Department of Public Health:
I am writing to share scientific information about artificial turf and playground surfaces, which I am
confident will help you determine what is best for the children and adults in your community.
As President of the National Center for Health Research, I am writing at the request of many of
your constituents 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 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 strongly support your county-wide ban on artificial turf, and urge you to also ban artificial turf
on the Fairground Sports Complex. We understand that these issues are hotly debated, but some
information is more accurate than others. For example, if you look at the maintenance contract for
an artificial field, you will see that it needs to be watered regularly to keep its warranty in place. In
addition, artificial turf fields use herbicides and pesticides, just as grass fields do. Although grass
fields and artificial turf fields both require water and pesticides, well-designed grass fields are safer,
more environmentally safer, and will last much longer and be more cost-effective.
In the last few years, scientists have learned more about lead and PFAS in artificial turf, as well as
the risks of some of the newer infill materials that are available 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. The use of silica sand and other infill materials also has substantial risks. For example, it is
well known that “particulate matter” can cause lung problems and eventually cause lung cancer.
For that reason, silica and zeolite are of great concern. Although they may claim it does not contain
PFAS, that is based on very limited testing. There are thousands of PFAS chemicals, and some
worrisome PFAS chemicals have been found in BrockFILL tested by independent researchers.
Please note that while the manufacturer claims that BrockFILL “meets the requirements of the FIFA
quality programme for synthetic turf systems as well as those of World Rugby” those requirements
do NOT evaluate long-term safety for either children or adults. Unfortunately, there are zero testing
criteria for artificial turf materials’ long-term safety, making such claims misleading as well as
meaningless.
In addition to the infill, the plastic grass itself exposes children and adults to dangerous levels of
PFAS, microplastics, and other toxic chemicals as well. PFAS are of particular concern because
they enter the body and the environment as “forever chemicals,” which means that they are not
metabolized and do not deteriorate, accumulating over the years.
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. The 2024 EPA report is not a “risk assessment” evaluating the impact of
artificial turf fields on children; it focused only on tire crumb, not on PFAS, microplastics, or other
exposures typical of artificial turf fields whether or not they have tire crumb infill. Unfortunately,
the EPA report was focused on issues that were selected many years ago, and not on the exposures
the health issues and environmental issues of greatest concern today. Although some will point to
the EPA report as a ‘clean bill of health” for artificial turf, that is completely untrue.
Lead
As you probably 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. The Centers for Disease Control and Prevention (CDC) warns that the “plastic grass” made
with nylon or some other materials also contains lead. Whether from infill, plastic grass, or rubber
playground surfaces (including PIP, which is made with tire crumb on the top layer or underneath
the top “poured in place” layer), the lead doesn’t just stay on the surface. With wear, the materials
used in rubber playground surfaces turn to dust containing lead and other chemicals that is invisible
to the eye and is inhaled by children when they play. In addition, PIP surfaces wear out and crack,
and the tire crumb are then on the surface where small children like to play with it and put it in their
mouths.
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 However, rubber playground surfaces contain many of the same dangerous
chemicals as tire crumb, since they are very similar materials, also made from petroleum. A 2018
report by Yale scientists detected 92 chemicals in samples from 6 different artificial turf companies.
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
Numerous studies indicating that the hormone-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, endocrine-disrupting chemicals 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
Newer studies are demonstrating the contribution of skin exposure to the development of respiratory
sensitization and altered pulmonary function. Skin exposure contributes to the cumulative exposure
to chemicals; in addition, skin is a highly biologically active organ capable of chemical metabolism
and the initiation of a cascade of immunological events, potentially causing harm 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. 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 is no conclusive evidence that a specific 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 Centers for Disease Control and Prevention,
the Environmental Protection Agency, the U.S. Consumer Product Safety Commission as well as
state legislatures, health officials, 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).
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, in communities
across the country, and on a national level. The question must be asked: if they had all the facts,
would your community choose to spend millions of dollars on fields that are less safe than well-
designed natural grass fields?
Dangerously Hot and Hard Fields
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 or
100-degree day is likely to be even hotter than 150-170 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 score. A Gmax score over 200 is considered
extremely dangerous, and it is considered by industry to pose a death risk. However, the synthetic
turf industry and American Society for Testing and Materials (ASTM), suggest scores should be
even lower — below 165 to ensure safety comparable to a grass field. Will your community pay to
have these tests conducted annually 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 safety is supposed to be
determined by the score of the hardest part of the field.
Environmental Issues
In addition to the health risks to school children and athletes, approximately three tons of infill
materials migrate off each synthetic turf field into the surrounding 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, and UV inhibitors, which can be toxic to marine and aquatic life.
Microplastics are known to migrate into the oceans, the food chain, and drinking water, and they
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; abate noise; and reduce glare. 12
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 as particulate matter that can harm
the lungs.
In response to the concerns of educated parents and government officials, other new materials are
now being used for infill instead of tire crumb and other very controversial materials. However, all
the materials being used 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 decision about artificial turf and
playground surfaces can save lives and improve the health of children in your community. You owe
it to your community to make sure that you know the risks of artificial turf and do all you can to
protect your children from both the known risks and the suspected risks. Your decisions about
artificial turf 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. 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, PhD
President
References
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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
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multiple methods from commercially available crumb rubber mulch. Water, Air, &
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