Manure from Chinese pig farms contains both antibiotic residues and high concentrations of bacteria that are resistant to antibiotics, a new study published Monday by the Proceedings of the National Academy of Sciences. The study adds to evidence that antibiotics used by China’s pork producers pose health risks. The study, led by the Chinese Academy of Sciences, found there is a risk of antibiotic resistance moving into the bacteria that infect humans and make the resulting diseases more difficult to treat. James Tiedje, Michigan State University microbiologist, assisted in the study and said the Chinese were “quite forthcoming.” Antibiotic residues in pig manure was monitored at three Chinese pig farms. Tiedje said the study did not intend to single out China’s pig farms as antibiotics in pig manure is a worldwide problem, with similar findings already recorded in Europe. In China, Tiedje found more than 100 different resistance genes with levels 200 times higher than in manure from pigs that had never used antibiotics. They study also found that once manure leaves the farm, its potential for spreading antibiotic resistance to other surrounding bacteria in the environment is much diminished. Pork production with antibiotic use has been growing rapidly in China, where half of world’s pigs are grown for a country with a growing appetite for pork.