Synthetic athletic tracks have been blamed for making dozens of students sick at a primary school attached to a Chinese top university in Beijing, state-run radio reports. Since October, at least 38 students from a primary school attached to Tsinghua University were reported to have suffered headaches, stomachache, vomiting or nose bleeds, while medical tests showed traces of the industrial chemical benzoic acid in their blood and urine, according to the report carried by China National Radio. READ MORE: Toxic trouble: Chinese children fall ill after inhaling fumes from newly laid school running tracks Parents had suspected the sickness was in some way linked to the recently finished rubber running track, the report said, and a few students stopped going to the school. But, according to an environmental test report provided by the school, the materials used in constructing the rubber track, which was finished on October 15 and has not been used since, all complied with safety standards. The school’s report, however, was regarded with suspicion by parents and some environmental inspection experts because it tested the air quality of the playing field that included running tracks according to standards for indoor air pollution control, which do not apply to the outdoor venues, according to radio report. READ MORE: Running on fumes: Shanghai schoolchildren’s nosebleeds, rashes and coughs blamed on athletics tracks, sparking city-wide probe Thepaper.cn, a Shanghai-based news portal, quoted Shi Jianhua, an expert from the China Environmental Protection Association who participated in drafting the standards for rubber tracks, as saying: “Just because the air quality around the rubber track complies with standards doesn’t mean that the rubber track itself complies.” Shi said the simplest way to test the quality of rubber tracks was by nose: if it smelt suspicious, then it might be problematic. Otherwise, the school need to send a sample of the rubber for testing at a government-approved lab. The school admitted that the track gave off “a pungent odour” when it was installed in October, but they suspended the work immediately and arranged for pupils to take their classes elsewhere, the report said. A few medical experts said that the benzoic acid might have come from medicine or food in addition to the rubber tracks, but this would not pose a health threat unless it was consumed in a large quantities. Other schools around the country, including in Shenzhen, Shanghai, and Jiangsu province, have reported similar problems of children becoming ill from rubber tracks that contained industrial chemicals that exceeded national standards.