The National Institute of Environmental Health Sciences and the National Human Genome Research Institute, both part of the NIH, said they would work with the EPA to make sure the newer methods are more accurate before expanding the program.

Animal testing has been the backbone of scientific research but NHGRI director Dr. Francis Collins said it does not predict very well what a chemical will do to a human being.

"It's slow. It's expensive," Collins told reporters in a telephone briefing. "We are not rats and we are not even other primates," he added.

"After all, ultimately what you are looking for is, does this compound do damage to cells? Can we, instead of looking at a whole animal, look at cells from different organs?"

The collaboration is starting out slowly and will cross-check the new rapid tests, called high-throughput tests, against older tests of known toxins.

"We need to exactly figure out what the correlations will be between animal testing and this high-throughput approach," Collins said.

"You cannot abandon animal testing overnight," added NIH director Dr. Elias Zerhouni.

NIEHS head Dr. Samuel Wilson said automated labs can now use non-animal methods to test 100,000 compounds in up to 15 concentrations in two days.

"One person would have to work eight hours a day, seven days a week for six months to do that. It's much, much faster," Wilson said.

Writing in the journal Science, the NIH and EPA noted that between 10 and 100 tests can be run in a year using live rodents such as rats and mice. Tests can be done more quickly using alternative animals such as fish and fruitflies.

But more than 10,000 tests can be run every day using specialized cells or lab chips.