Most artificial turf these days incorporates rubber granules formed from recycled tires. They make an effective and environmentally friendly playing surface. But can the substances they contain also be bad for the health of players?

A major report from NBC News this week examined possible associations between these granules and cancer cases amongst sports players who experience high exposures.

Soccer goalies at elevated risk?

At the heart of the report are anecdotal accounts of elevated cases of cancer amongst young soccer goalkeepers who play regularly on artificial turf.  These players typically have much closer contact with the granules as they protect the goal, and end up getting them in their clothing, their mouths, and in skin abrasions.  The connection drawn between goalkeepers, artificial turf, and cancer, is tenuous – all the more so as published research indicates exposure to carcinogens from recycled tire granules does not lead to significant increases in risk.  Nevertheless, NBC News suggest that there may be a possible association here that deserves further investigation.

Plausible connections

I must confess that I’ve never so much as kicked a ball around on an artificial turf pitch, and the closest my kids have come to artificial turf is my son’s participating in his school’s marching band during football season.  As a result, this isn’t an issue I was aware of before reading the NBC News article.  But having had it brought to my attention by a student, I was intrigued by the seemingly plausible connection that was made between a very specific subset of sports players and incidents of cancer.

According to NBC News, Amy Griffin, Associate Head Coach for the University of Washington women’s soccer team, has been collecting anecdotal information on cancer amongst soccer players for the past few years.  Of the 38 US soccer players she is currently aware of who have developed cancer, 34 of them are goalies.

This high percentage of goalkeepers amongst players with cancer – nearly 90% – may be entirely coincidental.  Certainly, without a well-designed research investigation, it’s not possible to tell whether this is due to reporting bias, randomness, or whether there’s is something more to the information.  And yet, reading the NBC News account, I was struck by the plausibility of an association between a material that is known to include small amounts of cancer-causing substances, and a group of people who most likely had higher than average exposures to this substance.

The rubber granules used in modern artificial turf often contain small quantities of harmful substances – from metals such as lead and zinc, to a range of organic compounds.  A recent paper in the journal Environmental Science & Technology for instance reviewed data on chemicals found in drainage water from  artificial turf fields, and reported measured concentrations of over 40 substances associated with recycled tire-based granules.  And according to NBC News, soccer goalkeepers are more likely to be exposed to these granules than other players.  The granules get into their clothes, into their mouth, and are even driven into the skin abrasions that are part and parcel of being an active goalie.

So thinking there may be an increased chance of goalkeepers developing cancer seems reasonable.  Yet “reasonable” doesn’t necessarily mean “right”.

The state of the science on artificial turf and health risks

One of the most prominent challenges to drawing a causal link is what is known from current research on artificial turf and potential health impacts.  While there is certainly the  possibility of exposures to cancer-causing compounds being sufficiently high to cause concern, there is currently no evidence at present to suggest that this is in fact the case.  The weight of evidence to date from studies looking at exposure to chemicals in recycled rubber-based artificial playing surfaces indicates that exposures through inhalation, ingestion and skin absorption are too low to raise concerns.

As an example, a 2009 study by the US Environmental Protection Agency (EPA) for instance concluded “On average, concentrations of components monitored in this study were below levels of concern”.  And the 2014 Environmental Science & Technology study by Cheng and colleagues similarly found that the quantities of potentially harmful substances leaching out of artificial turf were very much lower than the levels that would raise health concerns.  The review found that, while these granules may contain detectable quantities of substances known to be harmful, research to date indicates that most of those substances tend to stay in the granules, and don’t present a significant risk to people or the environment.

The one substance that has raised more concerns than most is the metal lead.  In some cases, high levels of lead have been found in dust from artificial turf (see for instance this report from the US Centers for Disease Control and Prevention).  Given the high toxicity of lead – especially to children – many producers and users of artificial turf have been proactive in ensuring the use of products to prevent unsafe exposure levels (for example, see the New York City Department of Parks & Recreation response to  lead and artificial turf).

Tradeoffs

But the decision to use artificial turf goes beyond possible health implications of specific chemicals.  Contemporary artificial turfs have lower maintenance costs than natural turf, use less water, and don’t require the use of potentially harmful pesticides.  There are also suggestions that artificial turf surfaces may result in less injuries than natural ones, although these evidence here is not conclusive (for example, a 2010 study in the Clinical Journal of Sport Medicine indicated that natural surfaces may lead to less injuries).  These upsides are important, as until more is known, there is a real risk that not using artificial turf may in fact increase health impacts.

Further research

That said, the hints that there may be a particularly vulnerable group of sports players susceptible to health impacts from playing on artificial turf should not be ignored.  While research to date indicates no significant elevated risk through inhaling, ingesting or touching the rubber granules, I’ve not been able to find published research on exposure through abrasions.  This may well turn out to be just as insignificant a route of exposure to trace amounts of harmful substances in the granules.  But given the observations of Amy Griffin and a largely unexplored exposure route within a specific group of artificial turf users, more research would seem warranted.  Just to be sure.

Additional resources

Environmental and Health Impacts of Artificial Turf: A Review (2014). Cheng et al.  Environ. Sci. Technol. 2014, 48, 2114−2129.  DOI: 10.1021/es4044193

Bioaccessibility and Risk of Exposure to Metals and SVOCs in Artificial Turf Field Fill Materials and Fibers (2014).  Pavilonis et al. Risk Analysis, Vol. 34, No. 1, DOI: 10.1111/risa.12081

Artificial Turf Football Fields: Environmental and Mutagenicity Assessment (2013). Schiliro` et al.  Arch Environ Contam Toxicol (2013) 64:1–11.  DOI: 10.1007/s00244-012-9792-1

Health Risk Assessment for Artificial Turf Playgrounds in School Athletic Facilities: Multi-route Exposure Estimation for Use Patterns (2012).  Kim et al. Asian Journal of Atmospheric Environment Vol. 6-3, pp.206-221 DOI: 10.5572/ajae.2012.6.3.206

Artificial-turf playing fields: Contents of metals, PAHs, PCBs, PCDDs and PCDFs, inhalation exposure to PAHs and related preliminary risk assessment (2011). Menichini et al. Science of the Total Environment 409 (2011) 4950–4957.  DOI: 10.1016/j.scitotenv.2011.07.042

Characterization of substances released from crumb rubber material used on artificial turf fields (2010). Li et al. Chemosphere 80 (2010) 279–285.  DOI: 10.1016/j.chemosphere.2010.04.021

Incidence of Injury Among Adolescent Soccer Players: A Comparative Study of Artificial and Natural Grass Turfs (2010).  Clinical Journal of Sport Medicine 20, 1 pp 1-7.  DOI: 10.1097/JSM.0b013e3181c967cd

A Scoping-level Field Monitoring Study of Synthetic Turf Fields and Playgrounds (2009).  EPA.  EPA/600/R-09/135 November 2009.  http://www.epa.gov/nerl/features/tire_crumbs.html

Hazardous chemicals in synthetic turf materials and their bioaccessibility in digestive fluids (2008).  Zhang et al. Journal of Exposure Science and Environmental Epidemiology (2008) 18, 600–607.  DOI: 10.1038/jes.2008.55

Image: Christopher Johnson – Flickr: Women’s soccer gains millions of new fans at London Olympics. Used under Creative Commons License. Source: Wikipedia