Students at nearly two-dozen schools in Shanghai were ordered to stop wearing their uniforms after officials said a toxic dye was found in the clothing. A potentially cancerous-causing dye, aromatic amine, was found in one batch of clothing sold to youths at 21 elementary and junior high schools, Xinhua reported Monday. The Shanghai Ouxia garment company produced the clothing in July 2012, the Shanghai Municipal Bureau of Quality and Technical Supervision said. Ouxia, which produces about 15,000 school uniforms anually, is one of several firms that have made uniforms for Shanghai students for the past five years, officials said. The standards agency said the toxin was detected during a recent quality-inspection campaign.