Turf Wars

Parent Groups On Social Media Are Abuzz Over Artificial Turf

As the mother of two young kids, I am a member of dozens of parent groups across all social media apps. As usual, I find that social media is a double-edged sword and that these parent groups can be a wonderful source of support and good information while also being a breeding ground for misinformation. (Fun fact: when I lived in Florida, I was kicked out of a local parent group on Facebook for being too “pro-vaccine” after I responded to false claims about “dangerous chemicals” in vaccines— I wear that as a badge of honor. But, I digress…)

Lately, I have noticed some heated exchanges over the safety of artificial turf. My kids have dabbled in sports (soccer, lacrosse, etc.) — but only on real grass, so I haven’t been exposed firsthand to artificial turf. But claims circulating online are making some parents hesitant to allow their kiddos to play on artificial turf (this includes headlines from major media outlets such as The Washington Post, Reuters, and AP News, to name a few).

So that got me wondering— should we be concerned? What does the science say? By now you know that my modus operandi is to remain calm, recognize that most scary-sounding claims are exaggerated and/or taken out of context, and have confidence that our regulatory bodies would flag any truly concerned levels of chemicals or dangers lurking in products.

When my team and I dug into the research on this topic we found a whole lot of conflicting information and data. The punchline of what I am going to present in this newsletter is this: there are some concerning data about the levels of certain chemicals (PAHs, VOCs, etc.) when it comes to artificial turf. But the data are not conclusive and we undoubtedly need more research on this topic.

Would I allow my kids to play on artificial turf? Yes, I would. Based on the data I have reviewed, occasional exposure to artificial turf does not convince me that short-term exposure poses a significant threat to human health. However, this doesn’t mean that there isn’t room for artificial turf to be improved and for policies to be put in place to limit ingredients of concern (and to make artificial turf more sustainable and environmentally friendly). Let’s get into it.

What is Artificial Turf? 

Simply put, it’s fake grass that has been manufactured with various synthetic materials to resemble natural grass, and used in its place in sporting facilities, landscaping, and schools.

A Brief History

Why the buzz?
Artificial turf playing fields have popped up nationwide in schools and parks. Initially believed to be a more environmentally friendly, cost-effective, and lower maintenance alternative to natural grass, artificial turf has come into the spotlight with claims about its propensity for injuries, adverse health effects, and environmental damage.

Concerns have been raised about the presence of PFAS (per- and polyfluoroalkyl substances) in artificial turf, also known as ‘forever chemicals’ due to their ability to resist decomposition and persist ‘forever’ in the environment. PFAS are a group of man-made chemicals used in various products to repel water and grease.

If you need a refresher on PFAS, there’s an episode of Unbiased Science that has you covered!

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A post shared by @unbiasedscipod

Composition of Artificial Turf
In order to address some of the health and safety concerns posed by artificial turf, it is important to understand its composition:

Image adapted from The Centre for Textile Science and Engineering

• Turf fibers are the “blades of grass” and are usually made of plastic.

• The infill is usually a mixture of crumb rubber from old tires and sand.

• The backing is a bottom layer made of either polyurethane or polypropylene, that acts as a base for the infill and for the fibers to be attached.

Crumb Rubber Infill

Crumb rubber infill is usually made from recycled tires, and used as the soft and spongy service of a playing field, in the case of artificial turf. This, in particular, has been a topic of interest for some people concerned about the health implications of artificial turf. A recent study out of Yale University found the presence of 197 potentially carcinogenic chemical agents in crumb rubber infill, of which 19 are labeled as carcinogens by American and European government agencies. This has understandably raised concerns about the potential release of these harmful chemicals into the bloodstream and airways— and the risks to human health.

Chemicals of potential concern in turf include polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and metals, such as zinc and lead. Players and athletes may be exposed to PAHs and VOCs from either inhalation, ingestion, or topically. 

The table below shows some of the PAHs and their respective category of carcinogenicity they fall under as per the International Agency for Research on Cancer (IARC). A note of caution: remember that the dose makes the poison— and while something may have the potential to be carcinogenic, we must be mindful of the exposures necessary to pose an actual risk to human health.

The maximum contaminant level for benzo(a)pyrene (BaP) in drinking water is 0.0002 mg/L or 0.2 ppb as determined by the EPA  (Agency for Toxic Substances and Disease Registry 2023). 

An Italian study looking at the exposure to BaP among athletes using artificial turf found that the average athlete inhales ~ 0.06 to 0.45 μg/kg body weight (bw) per day, which is significantly greater than the recommended safe limits of 0.06 to 0.50 ng/kg bw per day for BaP. Not a very encouraging finding— however, before you panic, consider the following: 1) doses and exposure duration: the study mentions daily inhalation, which might not reflect real-world exposure patterns. How often and how intensely someone plays on artificial turf can significantly affect their exposure levels. 2) individual factors: body weight and breathing rates can influence how much BaP someone inhales. The study provides average estimates, which may not accurately reflect individual exposure; and 3) risk interpretation: while the study shows that exposure exceeds recommended safe limits, these limits are often set with a considerable safety margin to protect public health. Exceeding them doesn't necessarily translate to immediate or severe health risks.

The National Toxicology Program conducted a meta-analysis of multiple studies and found no discernible risk to mice from crumb rubber infill exposure, but they did find evidence of some cell death in human cells when crumb rubber was exposed to high heat and leached chemicals. 

Several other studies have been conducted that also show no discernible association between crumb rubber exposure in artificial turf and adverse health outcomes. While some studies have found an elevated risk of poor outcomes, these studies have lacked rigorous data monitoring and long-term data, and have generally utilized only small samples of people. Due to the inconclusiveness in data, more comprehensive studies are needed to identify whether crumb rubber infill poses significant health risks. 

Seemingly in the interest of erring on the side of caution, some government agencies have recommended that crumb rubber in artificial turf playing fields be banned.

PFAS in Artificial Grass

Concern about PFAS in synthetic grass began in 2014 when a soccer coach shared his observation that there may be a potential link between soccer players playing on artificial turf and developing cancer, after tracking how many of his former goalkeepers and athletes developed blood cancers.

However, studies have been conducted that have shown no discernible link between artificial turf and developing cancer. 

A recent study conducted by the Public Employees For Environmental Responsibility (PEER) group, looked at the presence of PFAS in artificial grass playing areas by testing a group of soccer players.

The study required players to wipe their hands with a PFA-free wipe, and then have the wipe sent off to a commercial lab to determine the presence of PFAS.
Laboratory testing found that the amount of PFAS on three out of four players or coaches' skin almost doubled after playing on artificial turf, whereas when playing on a natural grass surface- the amount of PFAS on the hands had decreased. 

PEER does provide a disclaimer that this was only a preliminary study and that more research is needed to further support these preliminary findings about dermal absorption. Furthermore, the evidence behind dermal intake of PFAS is very minimal and as such, can not be directly attributed to PFA accumulation in the human body.

Although some have voiced concern about PFAS in synthetic turf, research and testing have been inconclusive as to how much is released during active play on artificial grass. Further, tests and studies by NGOs and local councils have determined the presence of fluorine in synthetic turf (fluorine indicates the presence of PFAS).

One study conducted in Sweden in 2022 determined that from a sample size of 51 synthetic grass specimens, 100% of the specimens contained fluorine (an element that's part of the chemical structure of PFAS). Detectable levels of PFAS were found in 42% of samples.

However, the bulk of studies conducted have been unable to conclusively determine whether the presence of PFAS is from the grass itself, or whether it is from environmental contaminants. Further, there is no consensus about a safe maximum limit of PFAS in artificial turf, and as such no specific limit has been established by regulatory boards.

The EPA has, however, established a lifetime exposure limit for PFOS and PFOA in drinking water to be 70 parts per trillion (ppt) combined. So how much are we exposed to via artificial turf?

PEER conducted tests on artificial turf at a high school in Easton, Massachusetts. They found 300 parts per trillion (ppt) of PFAS in the backing of the turf. (This means a very small amount of these chemicals was present.) PEER also tested discarded synthetic turf in Franklin, Massachusetts, and found 190 ppt of PFOS (a specific type of PFAS) in it. Other samples of artificial turf tested by PEER showed high levels of fluorine. The presence of fluorine in these samples suggests that they also contain PFAS, although further testing would be needed to confirm this.

Too Hot to Handle?

Artificial turf can get significantly hotter than natural grass in warm weather, raising concerns about heat-related injuries. Studies have shown that artificial turf can reach temperatures of 120-180°F (49-82°C), well above the 122°F (50°C) threshold for skin burns within 10 minutes. This poses risks of burns, heat stroke, and dehydration for athletes and can also damage sporting equipment.

While preventing turf from heating up is difficult, there are measures to mitigate heat-related risks. These include:

• Monitoring temperature: Regularly checking surface temperatures, especially during peak heat hours.

• Cancelling activities: Suspending sports or playing when the turf becomes dangerously hot.

• Scheduling: Limiting activities to cooler times of day, such as early mornings or evenings.

• Education: Training athletes, coaches, and parents on recognizing and managing heat-related illnesses.

Sprained ankles?

An observational study by the University Hospitals Sports Medicine Institute found a higher rate of injuries among high school athletes playing on artificial turf (58% more likely) compared to natural grass during the 2017-2018 season. Notably, injuries to the upper and lower extremities, as well as the torso, were more prevalent on artificial turf, particularly ACL injuries in football players. However, the study did not analyze why these differences existed, indicating further research is needed.

Conflicting evidence exists regarding injury rates on artificial turf. A systematic review by Paliobeis et al. (2021) reported no significant difference in overall injury risk for soccer and rugby players, though knee and ankle injuries were higher on artificial turf. Importantly, this review noted lower injury rates on third-generation artificial turf, the most common type in the US. Similarly, a systematic review by Gould et al. (2023) found an increased risk of foot and ankle injuries on artificial turf, but not necessarily a higher overall injury rate compared to natural grass.

Potential reasons for higher lower extremity injury rates on artificial turf include increased friction and torque due to the surface's coefficient of friction (COF). A 2015 study demonstrated that cleats on artificial turf do not form divots as they do on natural grass, leading to higher shearing forces and increased injury risk.

While some studies indicate a higher risk of specific injuries like foot and ankle on artificial turf, the overall injury rate compared to natural grass remains a topic of debate. Further research is needed to establish definitive associations and explore injury reduction strategies on artificial turf.

What about the environmental impact of artificial turf?

Despite its convenience and widespread use, artificial turf's relatively short lifespan of 8-10 years poses a significant disposal and recycling challenge. While some retailers repurpose and resell old fields to delay landfill disposal, the Synthetic Turf Council estimates a staggering 330 million pounds of artificial turf waste annually in the US alone.

Despite being marketed as recyclable, few facilities in the US or Europe can actually process artificial turf, leading most discarded fields to end up in landfills or haphazardly discarded. The lack of stringent state or federal regulations on artificial turf disposal and recycling exacerbates this issue, contributing to the accumulation of old fields in landfills.

Recycling artificial turf presents additional challenges due to the difficulty of separating rubber from sand in the infill, a time-consuming and expensive process. This further hinders recycling efforts and contributes to the overall environmental impact.

The scarcity of crumb rubber recycling plants in North America, coupled with regulatory gaps, means most discarded turf ends up in landfills. This highlights the need for improved recycling infrastructure and stricter regulations to address the growing environmental impact of artificial turf waste.

So…the jury is still out. The environmental impact of artificial turf versus natural grass is complex and depends on various factors. In hot, dry climates, artificial turf may be more sustainable due to its lack of water demand. However, natural grass might be preferable in milder climates where water is abundant. The frequency of field use, turf composition, local regulations, and long-term considerations like microplastic pollution and heat island effects also play a role.

Runoff and Water Quality

A recent study by Simpson and Francis (2021) found that artificial turf generates significantly more runoff than natural grass due to slower drainage and reduced water retention. This increased runoff raises concerns about the potential contamination of waterways with harmful chemicals often found in artificial turf.

Heavy metals and microplastics from artificial turf can leach into runoff and disrupt natural ecosystems. A 2023 study by Haan et al. identified microplastics from artificial turf as a major pollutant of waterways, accounting for up to 15% of larger plastic debris found in aquatic environments. This contamination may harm aquatic life and potentially impact human health through the food chain.

While artificial turf can offer benefits like reduced water usage in certain climates, its environmental impact, particularly concerning runoff, needs careful consideration. Mitigating runoff through proper drainage systems and choosing infill materials with lower environmental risks can help minimize potential harm to waterways.

So, what’s the bottom line?

I would be lying if I said I had any definitive answers or guidance for you. While research confirms the presence of potentially harmful chemicals like PAHs and VOCs in artificial turf, their concentrations and associated health risks are still being studied and, currently, no definitive safe limits have been established by regulatory boards. There are no conclusive data on health risks associated with the use of artificial turf. Certain elements of artificial turf, like crumb rubber, have been flagged as introducing potentially harmful exposure— so alternatives to their use are being explored. (Remember, though, there may be risks/associated with whatever is being used to replace it!)

Artificial turf offers undeniable benefits, such as year-round availability and durability in various weather conditions. But, there are downsides. Some research indicates a higher incidence of lower-extremity injuries and increased risk of heat-related illnesses on artificial turf compared to natural grass. Another consideration is that, despite being marketed as recyclable, the recycling and disposal of artificial turf pose significant challenges, with most discarded fields ending up in landfills.

Bottom line: the risks and benefits of turf have to be weighed on a case-by-case basis and vary based on a variety of factors. At this time, more data are needed to make any conclusive statements that can be generalized and standardized— especially about health risks. I, personally, am not too worried about the occasional use of artificial turf, but I do hope that we find ways to optimize turf and minimize the use of certain ingredients out of an abundance of caution, as well as to make it more environmentally friendly.