Evaluation of Health Effects of Recycled Waste Tires in Playground and Track Products

Recycled tires continue to be used in the construction of rubberized playground surfaces in California. To function as an effective means of reducing the incidence of serious head injury when children fall in the playground, these surfaces should meet standards for impact attenuation, as cited in the California Code of Regulations (sections 6570065750). This study was conducted to determine whether rubberized surfaces are meeting the standards for impact attenuation, and whether those properties change as the surfaces age. Data have been gathered from 32 rubberized playground surfaces and 5 surfaces made of wood chips/engineered wood fiber. An accelerometer was used to measure maximal deceleration rates (Gmax) and Head Impact Criterion (HIC) values for the surface below each play structure (131 tested) within the playgrounds, which were then compared to the American Society for Testing and Materials (ASTM) F1292 standard for impact attenuation by playground surfaces. Approximately 33 percent of the play structures on rubberized surfaces failed to meet the HIC standard, compared to no failures on wood chips. Approximately 69 percent of the rubberized playground surfaces contained at least one failing structure. Failing structures over rubberized surfaces included swings, climbers, slides, upper body rings and elevated platforms. As the heights of the play structures in rubberized playgrounds increased, so did the likelihood that the surface below would fail to meet the HIC standard, although some of the highest structures had underlying surfaces that met the standard. There appeared to be little or no difference in impact attenuation by surfaces less than one year old compared to surfaces that were between one and two years old. In addition, HIC values in two pour-in-place surfaces were stable for at least the first two to three months following installation. Lastly, HIC values of pour-in-place surfaces increased with increasing surface temperature. These results demonstrate the importance of testing rubberized playground surfaces following installation, to verify that the surfaces meet the standards for impact attenuation. Introduction Nationwide, up to 80 percent of serious playground injuries are the results of falls to the surface (Tinsworth and McDonald, 2001). Most were injuries to the upper limbs (Altman et al., 1996; Chalmers et al., 1996), although this varied with age; for children younger than five years old the head or face was injured most frequently, while for children 5-14 years old injuries to the hand or arm predominated (Tinsworth and McDonald, 2001). Epidemiologic studies performed with data from hospitals and daycare centers demonstrated that as the height of playground equipment increased, the injury rate from falls also increased (Briss et al., 1995; Chalmers et al., 1996; Mott et al., 1997; Macarthur et al., 2000). Less clear, however, is the influence of playground surface type on