The National Institutes of Health, America\'s foremost medical research agency, should scale back its use of chimpanzees for medical studies, an expert panel urged this week. An NIH-commissioned working group offered more than two dozen recommendations on how to best ensure the primates -- homo sapiens\' closest animal relative -- are used as test subjects only when absolutely necessary. The panel\'s findings are now open for public comment for 60 days before the NIH decides on implementing them. Such projects were already rare: of the 94,000 NIH-funded projects in 2011, only 53 used the primates. But in 2010, an NIH proposal to reintroduce 200 retired chimpanzees into research colonies caused public outcry. The controversy prompted the agency to ask for a study on the ongoing need for chimpanzees in NIH-funded research by the Institute of Medicine (IOM) -- an independent, nonprofit organization that aims to provide unbiased, authoritative advice to decision makers and the public about health matters. The IOM\'s findings led the NIH to order a halt to new funding for chimpanzee research while all ongoing studies using the apes could be reviewed by an NIH advisory working group. \"While used very selectively and in limited numbers for medical research, chimpanzees have served an important role in advancing human health in the past,\" the NIH said in a statement. \"However, new methods and technologies developed by the biomedical community have provided alternatives to the use of chimpanzees in several areas of research,\" it said. The United States is the only industrialized country still using primates for medical research, in particular for studies covering hepatitis C, AIDS, and malaria. The European Union formally forbade the practice in 2010, following Japan, Australia and other developed countries. The IOM concluded that most scientific experiments conducted on chimps could be done through other means. Nevertheless, chimpanzees may still be necessary in the development of vaccines against hepatitis C, for short-term continued study of monoclonal antibody research against bacteria and viruses, comparative genome studies and behavioral research, the report said. Many of the new recommendations focused on how to maintain the chimpanzees living environments. The expert panel said the animals should be kept in groups no smaller than seven individuals, with free, year-long outdoor access, and with at least 1,000 square feet (90 square meters) per chimpanzee. There were 937 chimpanzees in US research labs in 2011, including around 450 supported by the government. The rest were owned and used for research by private industry. In September 2012, the NIH announced it planned in 2013 to send 110 chimpanzees into retirement at a Louisiana sanctuary, joining the 109 retired chimps already there. In 2000, Congress allocated $30 million to finance such sites, which require about $20,000 a year to care for each chimpanzee. NIH is nearing that cap.