By Adam Mann

Documents made publicly available on October 14 have reignited a debate surrounding a proposed radiation experiment involving squirrel monkeys (Saimiri sciureus) at Brookhaven National Laboratory (BNL) in Upton, N.Y.

The heavily redacted papers, obtained by the animal-rights organization People for the Ethical Treatment of Animals (PETA) in Norfolk, Va., under the Freedom of Information Act, are titled "Decision regarding the disposition of NSRL Proposal N-249," the lab's designation for the radiation research. Although the heading suggests that the lab has reached a decision on whether to move forward with the work or not, the text is so heavily blacked out that it is impossible to tell what that decision is. The official line from BNL spokesman Peter Genzer is that the research proposal is still pending.

PETA and other animal-rights groups have watched for any news of the NASA-funded test since it was proposed last year. It marks the agency's first research involving primates in at least two decades. The experiment would expose the animals to charged-particle radiation in an attempt to reproduce the effects of cosmic rays on astronauts during a mission to Mars and to understand the effects of such radiation on the primate central nervous system.

"The major hurdle for human space exploration is not knowing the health risks to astronauts from exposure to cosmic rays," says Frank Cucinotta, head of the Space Radiation Health Project at the Johnson Space Center in Houston, Texas.

Earth's magnetic field protects crew members aboard the space shuttle or on the International Space Station from this type of radiation, but it would affect astronauts travelling farther afield.

Radiation risk

But PETA and other animal-rights groups criticize the methodology of the proposed test. On a long-term mission, humans would be confronted with low levels of radiation over a prolonged time, whereas the monkeys would be exposed to one dose over a period of minutes, says Justin Goodman, associate director of PETA's lab investigations department. "The actual experiment will teach us nothing about how astronauts will be affected in space," he adds.

Records from previous primate-radiation experiments as well as data from soldiers exposed to atomic-bomb radiation should suffice, adds Tim Phillips, vice-president of Animal Defenders International, an animal-rights organization headquartered in London.

Cucinotta defends the research, saying it will add to the slim database of information on the consequences of such radiation on the central nervous system.

Information from past experiments cannot be extrapolated to understanding whether or not radiation causes harmful neurological effects, says Gregory Nelson, a professor of radiation medicine at Loma Linda University in California, who is not involved with the proposed BNL experiment. The proposed test is different from previous experiments because it would look at results from exposure to charged particles of hydrogen, iron and silicon--known as heavy ions--all of which create micron-sized tears in tissue that are very different from the effects of high-energy radiation, he says.

Mission planning

The proposed research will also be distinct because it will monitor the monkeys for a number of years using memory and motor coordination tests, says Nelson. "It is necessary for NASA to understand any behavioral or cognitive changes to a crew member that would impair their ability to operate a spaceship," he says.

There is some evidence from rats and mice that heavy-ion exposure can produce memory deficits, but how those findings scale up to humans is unknown, he adds.

Animal-rights groups maintain that there are alternatives to the research. Cucinotta notes that NASA receives many proposals each year from universities across the United States on how to study the effects of space radiation, but that a better method has not been proposed so far. Information on radiation exposure will be needed soon, he adds, to assess risks for future manned missions in the 2020s--proposed by the administration of President Barack Obama-- that aim to return to the Moon or to explore asteroids.

The main goal of the primate research is to find out how low an astronaut's radiation exposure must be to ensure their safety, says Nelson. Before that can happen, researchers need a better understanding of the potential problems, he says. "Right now, the error bars are very big."