Animal Testing Alternatives

TESTING CHEMICALS on animals for human toxicity should be greatly reduced and can potentially be eliminated in favor of experiments using cells, cell lines, or cellular components, says a National Research Council report released last week.

Advances in systems biology and methods to test cells and tissues are fundamentally changing the way scientists can determine the risk chemicals pose to humans, the report says. It recommends a new approach to chemical testing based on emerging scientific understanding of how genes, proteins, and small molecules interact for normal cell function.

Such knowledge allows scientists to determine when exposure to chemicals perturbs cellular and biochemical functions enough to possibly cause disease, the report says.

Current methods of administering large doses of chemicals such as pesticides to laboratory animals—and then observing disease symptoms—may not be relevant to humans exposed to much lower levels of the substances, notes NRC committee member Melvin E. Andersen. He is director of the computational biology division of the Hamner Institutes for Health Sciences in North Carolina.

A growing body of knowledge from biological, medical, chemical, and pharmacological sciences is driving the replacement of current high-dose animal tests, Andersen says. He expects the alternatives to animal tests to include rapid, automated biologically based experiments that can evaluate hundreds to thousands of chemicals over a wide range of concentrations.

Such in vitro tests on cells, cell lines, and cellular components, preferably of human origin, would generate data more relevant to the risks people face from actual exposure to chemicals than do high-dose studies on laboratory animals, Andersen says. Use of in vitro testing would also expand the number of substances that could be tested and save time, money, and animals, he says.

"The committee believes strongly that, in the future, chemical testing will be based on human biology, and the use of animals will be much reduced and optimally eliminated," he adds. "Our vision is [for the next] 10 to 20 years, and we believe over that time testing will remain a mixture of the two, but a declining portion will be based on tests giving chemicals to animals."

For the foreseeable future, however, some animal tests will be needed to complement in vitro tests because current methods cannot yet adequately mirror the metabolism of a whole animal.

Changing from current, long-established animal-based testing practices to a cellular regime may run into resistance, the report notes. Consequently, a concerted effort will be needed to make the change, including formation of a free-standing institution to coordinate and foster new approaches to toxicity testing, the report says.

NRC's report, "Toxicity Testing in the Twenty-First Century: A Vision and a Strategy," is available online at books.nap.edu/catalog.php?record_id=11970.