By Sound News reporter Maggie Murdoch

The City of Seattle has a grand vision for Magnuson Park, that jewel of open space in NE Seattle along the western shores of Lake Washington.  Work restoring the natural beauty and social vitality of the park’s 360 acres has been underway since 1965, when the U.S. Navy base formerly located there began to consider giving the land to Seattle Parks and Recreation.

Now, Parks and Recreation is building a cadre of artificial turf sports field and redesigning several areas of wetlands, with the intention of enhancing wetland function and wildlife habitat, as well as drawing more park users.  These benefits may sound hard to argue with, but community activist Chris Van Dyk believes the fields are exposing humans and the Puget Sound environment to potential health risks that have not been adequately studied.

The five fields under construction at Magnuson Park are made with recycled tires ground up into pellets that are embedded in a plastic carpet, providing cushioning for athletes.

“A plastic and recycled tire playing field holds some 120 tons of granulated waste tire…the material is toxic,” Van Dyk warned.

Unexamined consequences on wildlife

The rubber in the fields contains traces of toxic metals and industrial chemicals that can cause cancer and other problems, and, in the case of sensitive wildlife, even death.  Several studies show that over 100 chemicals from the tire rubber can leach into the water that runs off the fields.  Van Dyk said that the studies that say they fields are safe are limited and cannot be considered conclusive.

Of particular concern at Magnuson is the fields’ proximity to several wetlands.  Pacific chorus frogs, alligator lizards, dabbling ducks, and numerous other species make their home in those seasonal wetlands.  The tiny pellets of ground-up rubber, about 1mm in size, can end up in the wetlands where they could be ingested.  Once inside an animal, the rubber won’t break down, and could cause fatal intestinal blockages.

Lynn Ferguson, a member of Magnuson Environmental Stewardship Alliance (MESA) who sat on the advisory committee for the field project said, “We don’t know what the impacts [of ingesting the pellets] will have on the wildlife” because the effects have never been studied.  Ferguson also said that little research exists that has examined the cumulative impacts of rubber runoff into the wetlands.

“That’s an issue, there just isn’t much research.  I think there are areas of concern, certainly, that should be followed and monitored very closely…In a way, this will be an ideal place to study that, because the frogs are an early indicator of pollution”

The City of Seattle is required by law to professionally monitor the wetlands.  The approved monitoring plan focuses mostly on the performance of the man-made wetlands, but does not consider the rubber pellets or its runoff.  The Magnuson project is the first time artificial fields have been placed so close to wetlands.  Ferguson and MESA will be collecting data on the number of Chorus frogs that return year after year.  However, if the frog population changes, their study won’t be sophisticated enough to draw causal links to toxics from the fields.  She hopes someone, perhaps at the University of Washington, will take up that research.

Artificial fields provide a myriad of benefits

In 2000, a City study found that existing fields were meeting only 50% of reasonable demand for their use.  Players often needed to drive to far away fields or settle for reduced playing time.  In the winter, teams either braved the slippery mud or delayed games for weeks, waiting for grass fields to dry.  Artificial fields help to make up the difference between supply and demand, in part because of their ability to be played on after a Seattle downpour.

Proponents of the fields tout benefits such as reduced pesticide and water use, longer field life, more use year-round, and lowered risk for joint injuries.  “Primarily the benefits come in the form of better play and greatly reduced maintenance costs,” said Dewey Potter of Seattle Parks and Recreation.  Potter estimates that the new fields at Magnuson can be used year-round and will last until 2018.

While the artificial fields are more expensive initially, over time they pay off because plastic grass doesn’t need to be watered, mowed, weeded, re-seeded, or closed for long periods of time during the wet season.

Potter said the City is not worried about toxic runoff because they use a product that does not contain lead, a pollutant found in some synthetic fields.  The Parks department referenced several studies that conclude that the amount of any given chemical that could end up in a player or spectator is too small to pose a threat.  One study from the Connecticut Department of Public Health compared the exposure a person might get from the fields to the quality of the metropolitan air, which is made up of 1-2% of dust from tire wear.

Another benefit of the fields, which are made up of 90% rubber by weight, is that they provide another use for some of the 300 million tires that Americans dispose of each year.

Are the risks acceptable?

Parks departments and local governments around the country believe the risks are so small that the fields should be used until problems can be conclusively connected to them.  But a major problem for any chemical research is understanding how chemicals will interact with each other, and how they will effect humans and the environment over a long span of time.

Van Dyk is skeptical of these claims of safety, particularly as the impacts accumulate as more fields are installed.  Artificial turf is fast becoming a standard replacement for natural grass fields.  In Seattle alone, Parks and Recreation and Seattle Schools co-operate 23 fields.  All have been built in the last fifteen years.

Several studies have been done on the effect of these industrial chemicals on human health.  However, not everyone agrees on their conclusions.  The non-profit Coastal Marine Research Center’s review of relevant literature concludes that not enough research has been done to conclusively indicate that the fields are safe—nor to conclude that they represent a de facto health risk.  Christopher Graham, the author of the review, said that there are enough red flags to enact the precautionary principle.  This would require the proponents and benefactors of artificial turf to prove the safety of the fields.

It is known that chemicals will leach from the fields during rain events, and that the lower the salinity and more acidic the water, the more likely the chemicals are to leach.  However, little study has been done on what concentrations of each of chemical in the runoff would pose a risk to various ecosystems.  Graham’s review of existing literature led him to believe that the concentrations would likely be small enough that the effects would remain local.

In the case of Magnuson Park, this means that at most, the wetlands surrounding the fields, and possibly the near shore lake environment would be affected.  But impacts add up, over time and from many sources.  Stormwater runoff, for example, is but one more source of tire rubber and other contaminants.  Stormwater has been identified as one of the major threats to the health of the Puget Sound region.

Like the evolving understanding of human impacts on natural ecosystems, much remains to be learned about how artificial fields fit into the larger picture of society and nature.  They contribute just a small percentage of the pollution that enters our air and water.  But the controversy over their safety provides some insight into the great environmental concerns of our time: How much is too much?  Should the fact that we breathe tire dust daily and use 300 million tires a year give cause for concern?  Where do we draw the line when deciding the safe amount of a carcinogen?  And what might the Pacific Chorus frog tell us about how we treat this planet, our home?