Skeptoid - Skeptoid #905: Artificial Turf: Poisonous Pitches?
Aired: 2023-10-10
Duration: 18:54


=== Invisible Chemicals on Turf (06:58) ===

[00:00:03]  Some people love sports fields covered with artificial turf, and some insist on natural grass.
[00:00:10]  Some say it's for the authenticity of the sport, some say it's for the performance of the athletes.
[00:00:15]  Still others insist that one surface or the other is safer for the athletes, with fewer injuries.
[00:00:22]  But the real problem might be one that's invisible, poisonous chemicals.
[00:00:28]  Artificial turf is coming up right now on Skeptoid.
[00:00:36]  Hi, I'm Alex Goldman.
[00:00:38]  You may know me as the host of Reply All, but I'm done with that.
[00:00:42]  I'm doing something else now.
[00:00:44]  I've started a new podcast called Hyperfixed.
[00:00:46]  On every episode of HyperFixed, listeners write in with their problems and I try to solve them.
[00:00:51]  Some massive and life-altering, and some so minuscule it'll boggle your mind.
[00:00:55]  No matter the problem, no matter the size, I'm here for you.
[00:00:59]  That's HyperFixed, the new podcast from Radiotopia.
[00:01:02]  Find it wherever you listen to podcasts or at hyperfixedpod.com.
[00:01:11]  You're listening to Skeptoid.
[00:01:12]  I'm Brian Dunning from Skeptoid.com.
[00:01:16]  Artificial turf.
[00:01:18]  Poisonous pitches?
[00:01:21]  Welcome to the show that separates fact from fiction, science from pseudoscience, real history from fake history, and helps us all make better life decisions by knowing what's real and what's not.
[00:01:35]  Artificial turf on sports playing fields is no stranger to controversy.
[00:01:40]  Normally, issues around artificial turf have to do with its costs, its durability, whether athletes perform better or worse on it, and whether athletes are more or less likely to be injured on it, all compared to grass fields.
[00:01:55]  But there's another objection to it that you may not have heard of, whether or not artificial turf outgasses harmful chemicals, which can impact the health of players and spectators, and also any wildlife that may be in the path of rain runoff.
[00:02:11]  Today we're going to point the skeptical eye at artificial turf to see whether they are indeed poisonous pitches or merely fresh fun fields.
[00:02:24]  The concern is certainly a plausible one.
[00:02:27]  Artificial turf is made mainly of plastics and rubbers, and those are compounds that do outgas after their manufacture.
[00:02:35]  But the variables here, and thus the complications, are myriad.
[00:02:40]  All of these complications are going to center around the guiding axiom for today, which is that it's the dose that determines the poison.
[00:02:49]  Any compound can be deadly in high enough concentrations, even water and oxygen.
[00:02:56]  And any compound can be safe in low enough concentrations, even ricin, VX, and plutonium.
[00:03:04]  So even if artificial turf puts out horribly toxic chemicals, if the amount is low enough, there's no cause for concern.
[00:03:14]  The compounds coming from artificial turf include known carcinogens, neurotoxicants, mutagens, and endocrine disruptors, including polycyclic aromatic hydrocarbons, phthales, and perfluoroalkyl and polyfluoroalkyl substances, PFAs.
[00:03:34]  Some of the harmful compounds are outgassed as VOCs, volatile organic compounds, and some of it is washed into the environment or can get onto a player's skin as leachate.
[00:03:47]  An environmental scientist could have a field day just listing off all the compounds that come off of artificial turf, no pun intended.
[00:03:56]  Some of this is from the crumb rubber which is shredded from used tires.
[00:04:00]  Some of it is from the plastic carpet fibers, basically the fake grass strands, and some of it comes from the tough plastic fiber base.
[00:04:09]  Depending on the brand and type, below that may be a synthetic fabric layer to prevent weeds from growing through.
[00:04:16]  Below that, a resilient synthetic shock-absorbing layer.
[00:04:20]  And below that, a foundation of one or more layers of crushed concrete, decomposed granite, gravel, or sand.
[00:04:29]  All of this results in an overwhelming majority of online articles on the subject declaring artificial turf fields to be chemically dangerous, especially to children.
[00:04:41]  And of course, there are the inevitable charges of industry conspiring to put profits ahead of children's health.
[00:04:48]  PFAs are universally brought up as the worst offender.
[00:04:53]  So it's worth a quick sidebar to examine PFAs.
[00:04:58]  There are literally thousands of compounds classed as PFAs.
[00:05:02]  They're used in countless products and have been for some 75 years.
[00:05:07]  They are one of those man-made chemicals that can be found in trace amounts virtually anywhere in the world, in wildlife, in groundwater sources and the oceans, in soil, in the air, and in plants.
[00:05:20]  What's the harm to people and to wildlife?
[00:05:23]  Well, you can read a thousand articles on the subject, but the answer is, we just don't know yet.
[00:05:29]  For decades, the National Institutes of Health, the Environmental Protection Agency, the Centers for Disease Control and Prevention, the Food and Drug Administration, and even the Department of Defense have been researching this.
[00:05:42]  The only thing you can say that's accurate to sum all of this up is that PFAs are one of those things we want to reduce, but we don't really know how dangerous they might be and at what dose they might pose a risk.
[00:05:56]  There's that all-important axiom again.
[00:05:59]  It's the dose that makes the poison.
[00:06:02]  Your last breath included some environmental PFAs.
[00:06:05]  Was it harmful to you?
[00:06:07]  There's no indication that it was, but there's insufficient data to prove it wasn't.
[00:06:14]  But we do have some data.
[00:06:17]  So far, every single published study on harm to people from artificial turf has found zero correlation with increased incidence of disease.
[00:06:27]  And that's a very important point.
[00:06:30]  We could end this episode right there, but we won't because that's too small a data set.
[00:06:36]  There have only been a few such studies, and they've only looked at cancer.
[00:06:41]  And they all include that universal disclaimer that's virtually a given at the end of every published study.
[00:06:47]  Say it with me, more study is needed.
[00:06:51]  According to all we've been able to learn so far, artificial turf does not increase anyone's risk of cancer.
[00:06:59]  What are the other risks beyond that?

=== Comparing Car Fumes to Fields (08:41) ===

[00:07:01]  We don't know yet.
[00:07:04]  One thing we do know about these sports fields is that they are outside, or at least inside large arenas.
[00:07:11]  There is plenty of ventilation.
[00:07:14]  Outside in the breeze, you're about as ventilated as it's possible to be.
[00:07:18]  So let's compare this situation to another one that we're all very familiar with, and that also involves the inhalation of outgassed chemicals.
[00:07:32]  Hey everyone, I want to remind you about a truly unique and once-in-a-lifetime adventure.
[00:07:38]  Join me and Mediterranean archaeologist Dr. Flint Dibble for a skeptoid sailing adventure through the Mediterranean Sea aboard the SV Royal Clipper, the world's largest full-rigged sailing ship.
[00:07:51]  This is also the only opportunity you'll have to hear Flint and I talk about our experiences when we both went on Joe Rogan to represent the causes of science and reality against whatever it is that you get when you're thrown into that lion pit.
[00:08:06]  We set sail from Malaga, Spain on April 18th, 2026 and finished the adventure in Nice, France on April 25th.
[00:08:15]  You'll enjoy a fascinating skeptical mini-conference at sea.
[00:08:19]  You'll visit amazing ports along the Spanish and French coasts and Flint will be our exclusive onboard expert sharing the real archaeology and history about every stop.
[00:08:30]  We've got special side quests and extra skeptical content planned at each port.
[00:08:35]  This is a true sailing ship.
[00:08:37]  You can climb the rat lines to the crow's nest, handle the sails.
[00:08:41]  You can even take the helm and steer.
[00:08:43]  This is a real bucket list adventure you don't want to miss.
[00:08:47]  But cabins are selling fast and this ship does always sell out.
[00:08:51]  Act now or you'll miss this once-in-a-lifetime opportunity.
[00:08:55]  Get the full details and book your cabin at skeptoid.com slash adventures.
[00:09:01]  Hope to see you on board.
[00:09:03]  That's skeptoid.com slash adventures.
[00:09:11]  Some research was published in April 2023 about the risk assessment of VOCs in new cars, and it went viral among the automotive press.
[00:09:21]  Researchers took a brand new mid-size SUV plug-in hybrid and parked it outside for 12 days, logging the temperature and humidity inside and outside and recording the VOC concentration at a number of sample points inside the car.
[00:09:37]  The seats, the carpet, the dashboard, the door trim panels, and so on.
[00:09:42]  Importantly, they also measured the AER, the air exchange rate, the rate at which air inside the car circulated out and was replaced with fresh air.
[00:09:53]  The important results include that the VOC concentration is driven mainly by temperature.
[00:09:59]  The hotter it gets inside the car, the more VOCs are outgassed.
[00:10:03]  And the thing most associated with reducing the VOC concentration is, if you can guess, ventilation.
[00:10:11]  The higher the AER, the cleaner the air.
[00:10:16]  So inside the environment of a new car, what exactly are the health risks of being exposed to those VOCs?
[00:10:23]  They calculated the ILCR, incremental lifetime cancer risk, for taxi drivers at 11 hours per day and for passengers at 1.6 hours per day for the three compounds of most concern, benzene, formaldehyde, and acetaldehyde.
[00:10:43]  An ILCR of 10 to the negative 6th or less is considered acceptable.
[00:10:50]  Only passenger exposure to benzene was below this level.
[00:10:55]  An ILCR of 10 to the negative 6th to 10 to the negative 4th indicates low risk.
[00:11:02]  And all the other metrics for both drivers and passengers were within this range.
[00:11:07]  Except one, the driver's risk for exposure to formaldehyde was just over 10 to the negative 4th, which indicates moderate risk.
[00:11:18]  This study was something of a worst-case scenario.
[00:11:22]  Brand new cars outgas VOCs at a much higher rate than used cars.
[00:11:27]  80% of all outgassing is done after only three months.
[00:11:32]  This study considered a taxi driver spending 11 hours a day inside a brand new car with minimal ventilation for his whole life to achieve the moderate risk level from a single compound.
[00:11:46]  Those of us who do most of our driving in cars older than three months will never, in our lifetimes, reach even the low risk level.
[00:11:58]  So this worst-case scenario, sitting inside a car with no ventilation, isn't all that bad.
[00:12:04]  It gives some perspective to the risk from playing a sport or even spectating on artificial turf, where you're not there for multiple hours every day and where you're outdoors with maximum ventilation.
[00:12:19]  This may seem like an unfair comparison, but just wait until you hear about a couple of these studies that were done, ostensibly to assess the risk of playing sports on artificial turf.
[00:12:30]  In one study, chicken eggs were injected with crumb rubber leachate, and then after the chicks were hatched, they were assessed for health issues.
[00:12:39]  They showed impaired development and endocrine disruption.
[00:12:43]  This was intended as an analog for athletes who come into transient skin contact with crumb rubber.
[00:12:49]  Clearly, it's not.
[00:12:51]  Those chicken embryos received a dose incalculably higher than the athletes might ever.
[00:12:58]  In another study, which I found particularly baffling, mummy chogs and fathead minnows were placed in a solution of water and the LC50 concentration of leachate.
[00:13:11]  LC50 is the concentration known to be lethal to 50% of test animals.
[00:13:17]  And some of them died.
[00:13:20]  I'm not sure what alternate outcome they expected.
[00:13:23]  This study was to assess the impact of tire wear particles on fish in estuaries.
[00:13:30]  Yet it's frequently cited in studies of runoff from artificial turf.
[00:13:35]  Unfortunately, this is the quality of study that we have to deal with on this subject.
[00:13:40]  As the authors all note, more and better study is needed.
[00:13:46]  We learned from the new car interior study that outgassing of VOCs decreases fairly rapidly over time.
[00:13:54]  And so we'd like to know the same thing about leaching of chemicals from crumb rubber.
[00:13:58]  Luckily, this has been thoroughly studied.
[00:14:02]  One representative publication from 2003 that assessed runoff from playgrounds found that impacts from leaching disappeared after the crumb rubber had been in place for three months.
[00:14:14]  The amount of leaching is directly proportional to the surface area.
[00:14:17]  And when an old used tire is shredded into crumb rubber, you're now exposing a lot of new surface area that had never been exposed before.
[00:14:26]  After three months, each crumb has pretty much leached out everything it's going to.
[00:14:31]  And so all of these issues with contaminated groundwater or harm to fish in nearby rivers are basically finished three months after installation.
[00:14:42]  And the same goes for any hypothetical harm to athletes who have transient skin contact with the crumb rubber.
[00:14:49]  Outgassing from VOCs and leaching from the rubber simply don't last long enough for any long-term impacts to build up.
[00:15:00]  However, even when we have a firm conclusion based on sufficient data, that conclusion is always provisional because more data might come out tomorrow.
[00:15:10]  When that happens, the size and thus the quality of our data set is improved and we can draw a new solution that's better supported.
[00:15:18]  On this topic, the most accurate description of our data is that it's inadequate.
[00:15:23]  We do have plenty of experience with artificial turf, and so far we've not observed any negative consequences to the health of athletes, spectators, or impacted wildlife.
[00:15:34]  But that doesn't mean we won't observe such consequences tomorrow.
[00:15:38]  The theory underlying the potential risk is perfectly sound.

=== Skepticism as the Best Medicine (03:11) ===

[00:15:43]  But the nature of the environments in which these fields are used mean that it's very unlikely that anybody could ever reach an exposure level that toys with our axiom of the day.
[00:15:54]  It's the dose that makes the poison.
[00:15:58]  Final conclusion number one.
[00:16:01]  Online claims that artificial turf presents a health risk, either to children or anyone else, are not supported by data.
[00:16:10]  Final conclusion number two, that might change in the future.
[00:16:14]  But unless and until it does, go out and enjoy your sports.
[00:16:19]  And now you can resume arguing about all the other issues around artificial turf.
[00:16:27]  In the ad-free and extended premium feed, we continue with the unlikely origin story of artificial turf, and it had nothing to do with professional sports.
[00:16:37]  To access it, become a supporter at skeptoid.com slash go premium.
[00:16:48]  A great big Skeptoid shout out to premium supporters Jordan Wiseman, Mike Parker from Melbourne, Victoria Johns, John Geyer, and Marcos.
[00:17:01]  Thank you all so much for making the show possible and supporting our nonprofit.
[00:17:05]  If you're a student or a teacher, don't forget our student questions episodes.
[00:17:10]  Record any question and I'll play it and answer it for you right here in a special episode.
[00:17:15]  Come to skeptoid.com and click on student questions.
[00:17:21]  Or support us by picking up an autographed Skeptoid book or a t-shirt in our online store.
[00:17:27]  We've got all the styles, sizes, and colors at skeptoid.com slash store.
[00:17:36]  You're listening to Skeptoid, a listener-supported program.
[00:17:40]  I'm Brian Dunning from skeptoid.com.
[00:17:48]  Hello, everyone.
[00:17:49]  This is Adrienne Hill from Skookum Studios in Calgary, Canada, the land of maple syrup and mousse.
[00:17:57]  And I'm here to ask you to consider becoming a premium member of Skeptoid for as little as $5 per month.
[00:18:06]  And that's only the cost of a couple of Tim Horton's double doubles.
[00:18:10]  And that's Canadian for coffee with double cream and sugar.
[00:18:14]  Why support Skeptoid?
[00:18:16]  If you are like me and don't like ads, but like extended versions of each episode, Premium is for you.
[00:18:23]  If you want to support a worthwhile nonprofit that combats pseudoscience, promotes critical thinking, and provides free access to teachers to use the podcast in the classroom via the teacher's toolkit, then sign up today.
[00:18:36]  Remember that skepticism is the best medicine.
[00:18:41]  Next to giggling, of course.
[00:18:43]  Until next time, this is Adrienne Hill.
[00:18:53]  From PRX