In a decision nearly three years in the making, the federal government's primary medical research agency has issued a final verdict on the use of chimpanzees in future scientific investigations.

The National Institutes of Health (NIH) today announced plans to sharply restrict — but not entirely ban — its involvement in biomedical research performed on captive chimpanzees. In a decision that aligns with earlier recommendations by an independent advisory panel, the NIH will no longer breed chimps and plans to send 310 captive chimps to sanctuaries. The agency had already issued an interim ban on new research projects involving chimpanzees, and is in the process of "retiring" some of them to more natural environs.

But in a controversial move, the agency will retain an estimated 50 animals for future projects. Those projects will need to be approved by a new review panel, tasked with determining whether or not chimps are "scientifically necessary" for the proposed endeavor. In particular, the panel's judgment will hinge on whether a project has the potential to significantly enhance public health, and whether an alternate research model exists.

"Americans have benefitted greatly from the chimpanzees' service."

"Americans have benefited greatly from the chimpanzees' service to biomedical research, but new scientific methods and technologies have rendered their use in research largely unnecessary," Dr. Francis Collins, director of the NIH, said in a statement. "Their likeness to humans has made them uniquely valuable for certain types of research, but also demands greater justification for their use."

Although chimpanzees are still widely used in biomedical studies, including investigations in neuroscience and comparative genomics, their role in recent years has been curbed due to new research techniques — some of which actually rely on other animals, including engineered mice and guinea pigs.

The NIH decision comes mere weeks after the US Fish and Wildlife Service proposed adding captive chimpanzees to its endangered species list. That move could curb the non-NIH use of chimpanzees for medical research, and limit the sale of chimpanzee blood and tissue across state lines.