Research Action Plan on Recycled Tire Crumb Used on Playing Fields and Playgrounds to study key environmental human health questions concerning the safety of recycled tire crumb. The EPA previously studied air and surface samples at four fields and playgrounds that use recycled tires. The limited study, conducted in August through October 2008, found that the concentrations of materials that made up tire crumb were below levels considered harmful. In addition, the overall study protocol and many of the methods were found to be appropriate and could be implemented in the field. The study, however, did note that due to its limited nature and the large diversity of materials used to make tire crumb, no definitive conclusions could be reached. More recently, the EPA has released a comprehensive spreadsheet with toxicity reference information. The California Office of Environmental Health Hazard Assessment (OEHHA) used guinea pigs, in an animal study, to test skin sensitization by playground surfaces made of recycled tires and observed no sensitization. This suggested that these surfaces would not cause skin sensitization in children, nor would they be expected to elicit skin reaction in children already sensitized to latex. The OEHHA has conducted additional studies on potential negative human health effects associated with the use of recycled waste tires in playground and synthetic turf products. Although rubber mulch is generally regarded as safe, recycled tire rubber leachates do contain certain minerals and compounds which may be ecotoxic in high concentrations. Recycled tire mulch can contain trace amounts of various minerals from the tire manufacturing process and other chemicals that may have been picked up during the tire's service life. The greater the surface area of synthetic rubber waste pellets, the greater the potential for breakdown into harmful constituents. For leached tire debris, the (potential) environmental impact of the ingredients zinc and organic toxicants has been demonstrated. See also Rubber Tire recycling Green building Plastic mulch Sustainable landscaping References External links New York artificial turf field study The Myth of Rubberized Landscapes Artificial Turf: Exposures to Ground Up Rubber Tires - Athletic Fields, Playgrounds, Garden Mulch Recycled building materials Pavements Tires