Two food shipments from the US have been impounded by China on safety grounds in what may be branded an act of retaliation following a recall of Chinese-made tires in America. China's General Administration of Quality Supervision, Inspection and Quarantine said on Tuesday that an orange pulp shipment had been seized in the eastern province of Shandong while apricots were being held in Shenzhen, the Financial Times reported. It said the shipments contained "excessive bacteria, mould and sulfur dioxide," and called on local agencies to "strengthen quarantine and inspections on food imports from America." A day earlier, the US road safety regulator recalled 450,000 tires made by Hangzhou Zhongce Rubber, which were being sold by a New Jersey-based distributor. The products lacked a gum strip used to reinforce the tire. Meanwhile, it was announced that 23,000 tainted or sub-standard foods were found in China between December and May, leading to the closure of 180 food manufacturers.