Ractopamine, a controversial veterinary drug used widely in pork production to boost growth and leanness, is limiting US meat exports. An investigation of U.S. Food and Drug Administration records found that more pigs were reported to have suffered adverse effects from ractopamine than any other pork drug. The report, produced by the Food and Environment Reporting Network and published on msnbc.com, found that ractopamine had not only sparked complaints about animal welfare, but had also raised concerns about potential human health impacts. China, Taiwan, the EU and others had all raised concerns about the gaps in science backing the safety of the drug, which as been approved as safe by the FDA. Much of the available research used in international and US safety assessments was sponsored by Elanco, the drug company that makes ractopamine.