BEIJING — Recycling used materials is great. School athletics, too! But in China this week, we see where the two activities should never cross paths.

The Tuesday night edition of Economic 30 Minutes, a program of CCTV, the Chinese state television broadcaster, exposed the shady story of China's plastic school tracks and sports fields made of “black beads,” a mixture of granules fabricated from scrap tires and other types of industrial chemical waste.

Over the past two years, there have been various news reports about children at certain schools suffering symptoms such as dizziness, nose bleeding, skin allergy, with the cases increasingly linked to participation on plastic school tracks or sports fields, according to the Beijing weekly Economic Observer.

Originally these plastic tracks were touted for their excellence in shock-absorption for the bodies of school athletes. But outrage is now spreading after CCTV's unannounced visit to the so-called “black beads” factory revealed that the material typically used to fabricate plastic tracks is composed of not only discarded tires, but is also crushed together with various types of rubber from undetermined sources, according to Caixin media.

Particularly when exposed to the heat of the sun, these sports tracks release toxic gases causing all sorts of discomfort to pupils. The Economic Observer reported that the crux of the problem lies in the fact that although there exist safe plastic runways with good materials, most Chinese schools go for low-end, low-cost products. Up until now China has failed to specify vigorous regulations for project acceptance, including detection of toxic substances such as formaldehyde, benzene or xylene.