Major Federal Agencies Accept Synthetic Skin Test As Substitute For Chemical Testing On Animals

Major federal regulatory agencies - the Environmental Protection Agency, the Occupational Safety and Health Administration and the Consumer Product Safety Commission - have agreed to accept chemical safety data from a synthetic skin test in lieu of an animal test, the National Toxicology Program announced today.

This is the first such general substitution of a non-animal test under a new federal program to reduce animal experimentation.

The regulatory agencies are preparing Federal Register notices to tell industry and other research institutions they can use the non-animal test for regulatory purposes. The regulatory actions were announced today by the National Toxicology Program, which is headquartered at the National Institute of Environmental Health Sciences in Research Triangle Park, N.C. NIEHS and other federal agencies support the Interagency Coordinating Committee on the Validation of Alternative Methods, an organization established in 1997 to foster alternative and improved test methods.

The Food and Drug Administration also endorsed the acceptability of the method, but said that corrosivity testing for the types of products it regulates is likely to be limited. Also, on a limited basis, the Department of Transportation has already been accepting the method for certain chemicals.

The new test can replace, in many uses, a method in which a chemical or chemical mixture was placed on the intact skin of a laboratory rabbit. Several thousand rabbits have been used each year in the old test, according to one estimate.

Under ICCVAM's sponsorship, a scientific panel performed a scientific review of the test and recommended it last year to the regulatory agencies. The panel said the new method could fully replace the use of animals for testing corrosiveness in some cases, while in others, when the chemical "passed" the screen as probably safe, an animal test would be required to confirm that the chemical is not corrosive. In addition, some chemicals cannot be evaluated in the assay, and these must be tested using the standard animal test, which requires one to three rabbits.

William Stokes, D.V.M., the National Institute of Environmental Health Sciences' associate director for animal and alternative resources, said, "The old test requirements called for three animals for each chemical that is evaluated for skin corrosivity and dermal irritation. Since there are more than two thousand chemicals introduced each year, the substitution of Corrositex could save many laboratory animals in a year."

Skin corrosiveness testing is conducted to ensure that chemicals and products are properly labeled to alert consumers and workers to take precautions to prevent chemical burns to the skin. Corrosion is more serious than skin irritation and involves permanent damage to skin, usually with scarring.

In the new test, developed under the trade name Corrositex, a chemical or chemical mixture is placed on a collagen matrix barrier that serves as a kind of synthetic skin. Once it penetrates the barrier, the chemical causes a color change in a liquid detection system composed of indicator dyes that are sensitive to strong acids and bases at pH extremes. The time it takes for a test chemical to penetrate the barrier and produce a color change in the detection system is compared to a classification chart to determine corrosivity.

In order to develop a scientific consensus on the usefulness and limitations of the new test, panel members evaluated all available information and data to determine the extent to which the ICCVAM criteria for validation and acceptance of new test methods was addressed.

This is the second substitute test to be approved by federal regulatory agencies after an ICCVAM panel review. The first review resulted in the acceptance by regulatory agencies of a test called the Murine Local Lymph Node Assay that uses fewer animals to determine the potential of chemicals to cause allergic dermatitis. The new, less painful assay also uses mice instead of guinea pigs.

Corrositex is sold as a test kit by InVitro International of Irvine, Calif.