The synthetic running tracks have been uninstalled. (Photo/China Daily)
Loopholes
Experts said synthetic running tracks are used across the world, from kindergartens to Olympic stadiums, and they are hazard-free providing they are manufactured and laid in accordance with specific chemical processes and quality-control standards.
Chen Jianding, a professor of materials engineering at East China University of Science and Technology, said improper processing and the use of cheap additives to improve surface resilience could result in an excess of free toluene diisocyanate, an organic compound used in the production of polyurethane foams, that can be toxic to humans.
He said the compound form of TDI, as used in running tracks, has low toxicity.
The national quality standard for synthetic playground surfaces sets no strict limits on the amount of free TDI that can be used and does not specify the types and concentrations of glues and plasticizers, which can also be toxic if mixed incorrectly.
Zhang Jinliang, an environmental safety researcher at the Chinese Research Academy of Environmental Sciences, said the lack of specifications for relevant chemicals in the air-quality monitoring standard means toxins exist even in environments classified as safe after testing.
"This explains most of the cases where post-construction air-quality tests were unable to detect the real toxins affecting students' health on low-quality rubber tracks," she said.
