October 8, 2025
To the Mayor, Town Council, Town Manager, and other officials of Kensington:
I am writing as President of the National Center for Health Research and at the request of many of your constituents to share scientific information about PIP and other artificial rubber playground surfaces, which I am confident will help you determine what is best for the children and adults in Kensington.
I have provided similar information 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. Our nonprofit think tank was founded in Maryland in 1999 and is currently located in Washington, D.C. I have lived in Montgomery County for 34 years, so I am especially interested in Kensington’s playgrounds. 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.
First, I want to emphasize that PIP playgrounds are especially harmful to children with asthma and allergies, because the chemicals in the artificial rubber can cause serious reactions in any children, but especially those who are already sensitive. And, since the surfaces regularly become 50-60 degrees Fahrenheit hotter than grass or engineered wood fiber, they are also harmful to many children. To be inclusive, it is essential that playground surfaces be safe for most children. Engineered wood fiber has no harmful chemicals and is ADA compliant. Unfortunately, parents of children with disabilities have often been targeted with misinformation about PIP and similar surfaces by individuals and companies with financial conflicts of interest’
In the last few years, scientists have learned more about lead and PFAS in PIP and other artificial rubber playgrounds. The top surface of a PIP playground covers a layer of recycled tire crumb (also called tire mulch or tire waste). 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. Although companies often claim that their products do not contain PFAS, that claim is not accurate because it is based on inadequate testing. There are thousands of PFAS chemicals, and companies that claim their products are “PFAS free” have tested less than a dozen of those PFAS chemicals.
Federal agencies such as the EPA and the U.S. Consumer Product Safety Commission (CPSC) have been investigating the safety of these products. Despite claims to the contrary, none have concluded that PIP playgrounds are safe. CPSC had started investigating these playgrounds when the majority of Commissioners were fired by President Trump this year.
Lead
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. The tire crumb below the top PIP surface at playgrounds in Maryland has been tested by independent researchers at the Ecology Center in Ann Arbor, and pieces have been found to have lead levels exponentially higher than what experts believe is acceptable. That is important because the top layer cracks or gets worn down with use, revealing pieces of tire crumb that small children get on their ears and mouths and sometimes intentionally eat. Go to any playground that is a few years old and you will see the black tire crumb showing in many areas, especially at the bottom of slides and other places that get worn by children’s feet or bodies.
Why are chemicals that are banned from children’s toys allowed in rubber playground surfaces?
Synthetic rubber is made with natural rubber (Latex) as well as petroleum, and includes endocrine (hormone) disrupting chemicals (also called EDCs). There is very good evidence of these chemicals in tire crumb, based on studies done at Yale and by the California Office of Environmental Health Hazard Assessment (OEHHA).[1] For example, a 2018 report by Yale scientists detected 92 chemicals in samples of tire crumb from 6 different 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 indicate that the hormone-disrupting chemicals found in rubber 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 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]
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 companies selling and installing these products 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).
Dangerously Hot Playgrounds
We all know that Kensington can get hot in the summer. Even when the temperature above the grass is 80 degrees Fahrenheit, rubber playgrounds 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 the playground. That can cause “heat poisoning” as well as burns.
Synthetic surfaces also create heat islands that contribute to climate change.
Conclusions
There have never been any safety tests required prior to sale that prove that any PIP 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 engineered wood fiber, which costs less and is much easier to maintain.
I have cited several relevant scientific articles 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, grandparents, and scientists who are very concerned about the impact of playground surfaces on your children and grandchildren. You owe it to our community to make sure that you know the risks of PIP playgrounds and other rubber surfaces in playgrounds and daycare centers, and do all you can to protect your children from both the known risks and the suspected risks. Your decisions 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 PIP 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, Ph.D., President
National Center for Health Research
References
- 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
- 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
- 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/