The scientists were unable to provide a specific time frame for when the technology might produce significant results or predict how many fewer animals would be used in testing if their effort is a success. They stressed that they plan to move quickly to test the new technology and reduce animal testing as soon and as much as possible.

But they acknowledged that some animal testing will continue at least until the technology proves its mettle in large-scale studies or until Congress passes a substance regulation act similar to the European Union's (E.U.) Registration, Evaluation, Authorization and Restriction of Chemicals, or (REACH), which regulates chemicals and their safe use. It is set to take effect in March 2009 and bans such testing.

The officials noted that despite the E.U.'s pending ban, it is unclear whether scientists in Europe have access alternative methods of toxicology testing. Wilson noted that the technology being tested by the EPA and NIH is not yet available in the E.U.

For now, NIH chief Zerhouni said, animal testing will continue in the U.S. in conjunction with the new high-speed, automated screening technology. There are several other approaches under development that would also allow relatively quick, inexpensive testing of a large number of compounds and cells simultaneously. "We plan to use all of these," Christopher Austin, director of the NIH's Chemical Genomics Center, said at the news conference.

As ScientificAmerican.com reported in December, researchers at Rensselaer Polytechnic Institute in Troy, N.Y., the University of California, Berkeley, and Solidus Biosciences, Inc. (a biotech company located at the Rensselaer Incubator Program for start-up businesses) have developed biochips—called MetaChip and DataChip—that mimic what the body does when it ingests a drug. MetaChip is actually a glass slide dotted with 20-nanoliter droplets—each 20 billionths of a liter—of a solution containing human liver enzymes; DataChip is a slide lined with droplets containing cell cultures from the bladder, kidney or liver. Scientists can test the safety of a chemical by putting drops of it onto these slides and measuring the culture's growth or shrinkage over time.

These biochips are used with a high-throughput microarray spotter machine that places the liquid enzyme dots on the slides. The next step involves an optical assay system consisting of a camera connected to a fluorescent light source to take a digital image of the cell culture and highlight living and dead cells. Austin noted, however, that MetaChip and DataChip are not currently capable of handling the volume of testing that the government wants to conduct.