The import bans are the latest action in the escalating trade tension between the US and China. In a letter sent to the Chinese authorities, the US Food Safety and Inspection Service (FSIS) has requested test results and any scientific information available that justify the restrictions, according to The Financial Times. The General Administration of Quality Supervision, Inspection and Quarantine says that salmonella was found in frozen chicken meat from Tyson Foods, while growth enhancer and anti-parasite drug residues were found in frozen chicken feet shipped by Sanderson Farms. Included in the import ban imposed by China are frozen pork ribs from Cargill Meat Solutions, salted pig innards from Triumph Foods, frozen chicken feet from Intervision Foods and frozen pig ears from Van Luin Foods USA. All of the plants in question meet US Department of Agriculture (USDA) hygiene regulations, although there are differences between US and Chinese safety standards. According to American Meat Institute (AMI), an industry body, all raw agricultural products can contain low levels of bacteria, including salmonella, but this is normal and allowed under USDA rules because the products are intended to be cooked. Patrick Boyle, president of the American Meat Institute said that the exported products could be safely eaten by US consumers, yet China has rejected them. "US food safety standards are among the most stringent in the world and our pork and poultry products are recognized for their safety," he said. "China's policies and actions to suspend these plants are inconsistent with the best available science." The ban on pork product imports comes at a time where a porcine reproductive and respiratory syndrome, which killed 40,000 hogs last week alone, is sweeping the country. With the hot weather expecting to prolong the outbreak, and a reported shortage of blue-ear disease vaccines, the pork import ban is likely to lead to product shortages and price rises. According to the AMI, exports of pork to China are up 51.3 per cent for January to May 2007 compared with the same time period in 2006. However, exports of poultry to China for January to May 2007 are down 7.4 per cent from the same period in 2006. According to USDA, the US exported 640 million pounds of poultry and 113.5 million pounds of pork to China in 2006.