2021 U.S. Scrap TIre Workgroup (USSTWG)

Questions about tire materials raise questions about scrap tire markets - 6ppd-quinone • Tian et al. 2020 – “In particular, scrap tires re -purposed as crumb rubber in artificial turf fields suggest both human and ecological exposures to these chemicals. Accordingly, the human health effects of such exposures merit evaluation.” • Department of Toxic Substances Control - Product – Chemical Profile for Motor Vehicle Tires Containing N- (1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) – “…crumb rubber made from scrap tires is used in a range of applications, including playground surfacing, porous walkways, paths and bike trails, and infill in synthetic turf fields. These and other materials made from recycled scrap tires may represent sources of exposure for the people and animals that use them. For example, people, including children, playing on synthetic turf may be exposed to 6PPD or 6PPD-quinone by inhaling or ingesting small crumb rubber particles or via dermal contact, especially when skin surfaces are wet or sweaty. As described above, 6PPD has been detected in crumb rubber from synthetic turf fields in the U.S., including California (OEHHA 2019; U.S. EPA and CDC/ATSDR 2019).” – “…6PPD slowly migrates from the interior of the tread to the surface of a tire over its lifetime, and thus the concentration of 6PPD in tires decreases over time. Nevertheless, analysis of used tires shows that they can still contain 6PPD, and the concentration can be significant.” 6