THE GEN 5 SYNTHETIC ATHLETIC SYSTEM
There are almost no studies on potential health impacts (especially long-term) from using tire rubber, but preliminary reports have found definitive evidence of potential risk. The California Office of Environmental Health Hazard Assessment (OEHHA), in a January 2007 report Evaluation of Health Effects of Recycled Waste Tires in Playground and Track Products, found that 49 chemicals could be released from tire crumbs.
Recycled crumb rubber contains a number of chemicals that are known or suspected to cause health effects. The most common types of synthetic rubber used in tires are composed of ethylene-propylene and styrene-butadiene combined with vulcanizing agents, fillers, plasticizers, and antioxidants in different quantities, depending on the manufacturer. Tire rubber also contains polyaromatic hydrocarbons (PAHs), phthalates, and volatile organic compounds (VOCs).
Rubber leachates are also complex solutions, some of which are known to be harmful to human health; effects of exposure range from skin and eye irritation to major organ damage and even death. Long term exposure can lead to neurological damage, carcinogenesis, and mutagenesis.
While these findings lead one to believe the material is indeed toxic, it is argued that since the rubber is “vulcanized,” the toxins are locked in. Some companies claim the material is indestructible and non-biodegradable, completely safe and non-toxic. Simultaneously, they admit that there is an odor at first (which is evidence of chemicals volatilizing from the materials not locked in after all).
Every study I have come across has only served to emphasize that the devil is in the details. It depends on what form the recycled rubber takes, what degree of usage is endured, and what climate and other environmental factors may impact degradation. Since there are relatively few studies on leaching and health impacts when using scrap tires in these various ways, I have had to try to examine the evidence already available from other uses and make assumptions about what it means for my daughter.
The State of Evidence (or Lack Thereof)
In 1994, the Minnesota Pollution Control Agency found that due to heavy metals and other pollutants in tires there is a potential risk for the leaching of toxins into the groundwater when placed in wet soils. Admitting the almost unpredictable nature of tires, this report stated “research has shown that very little leaching occurs when shredded tires are used as light fill material, however limitations have been put on use of this material; each site should be individually assessed determining if this product is appropriate for given conditions.”
A 1998 study from the University of Massachusetts reviewed all of the existing literature in order to assess the safety of using recycled tires as light fill in civil engineering projects. While they concluded that it appeared safe, they also stated that “it would be prudent to perform field studies on these areas over longer periods of time. It is important to recognize that the impact of scrap tires on the environment varies according to the local water and soil conditions, especially pH value.”