In a step that may reduce by thousands the number of guinea pigs used to test chemicals, the Consumer Product Safety Commission, the Environmental Protection Agency, the Occupational Safety and Health Administration, and the Food and Drug Administration are changing their procedures to accept results from a new test using mice - and fewer of them than the traditional guinea pig test. The alternate test is also less stressful to the animals.

The alternate test, like the traditional one, is needed to determine if a new chemical is likely to cause allergic contact dermatitis in workers and consumers.

The National Toxicology Program, which is headquartered at the National Institute of Environmental Health Sciences, announced the actions today. NTP said that the three regulatory agencies have reported they are accepting test results using the Murine Local Lymph Node Assay and changing their regulations accordingly.

In taking the new regulatory steps, the agencies concurred with a federally sponsored, independent scientific panel that the alternative assay could be used to identify whether or not chemicals may cause allergic contact dermatitis in workers and consumers. The scientific panel, which was convened by the new Interagency Coordinating Committee on the Validation of Alternative Methods issued its report - its first -- earlier this year after peer reviewing the assay in 1998. ICCVAM was fostered by the National Toxicology Program at NIEHS, with the latter's parent National Institutes of Health and major regulatory agencies, to foster good test methods using fewer or no animals.

According to today's announcement, the four regulatory agencies said they were in agreement that the rodent lymph node assay can be used in most instances instead of the traditional guinea pig-based test methods to assess the allergic contact dermatitis potential of chemicals. The alternate test can be done in a week as opposed to three to four weeks for the traditional method.

In the traditional test, the product was painted on the body and the guinea pig was then injected with an additional chemical to help accentuate the effect of the test chemical in developing dermatitis. In the new test, the mouse's ears are painted with the test substance and its immunological response is determined by examination of lymph node tissue.

The animal does not have to develop allergic contact dermatitis. Thus, the new test refines the procedure so that it is less painful and stressful than the traditional test. Also, in most testing situations, fewer animals are required for each test.

"If you have a chemical that's an allergen," according to a scientist who has worked with the test, "it stimulates the immune system so cells divide, and that's where we're looking." The test was first conceived by Ian Kimber at the Zeneca Central Toxicology Laboratory in England. Kimber collaborated with Frank Gerberick from Procter and Gamble and David Basketter from Unilever to further develop the method and to submit it to ICCVAM.

Contact dermatitis is a major problem for consumers of many products, including cosmetics and household products. It is also the second most common occupational disease, costing industry and workers as much as $1 billion annually in lost workdays and associated loss of productivity. Allergic contact dermatitis is caused by a variety of substances, from fragrances to some pesticides and industrial chemicals, which trigger an allergic or delayed hypersensitivity reaction.

The lymph node assay was the first alternative test method to be reviewed using the ICCVAM process. ICCVAM was established to promote the scientific validation and regulatory acceptance of new tests that will provide improved prediction of adverse effects than currently used methods, and hopefully will aid animal welfare and reduce animal use. It is a standing committee with participating federal agencies that include, in addition to those mentioned above:

• Department of Energy
• Agency for Toxic Substances and Disease Registry
• National Institute for Occupational Safety and Health
• National Cancer Institute
• National Library of Medicine
• Department of the Interior
• Department of Transportation
• Department of Defense

A second animal-conserving test was reviewed in January 1999 by an ICCVAM peer review panel and the panel's recommendations are currently under consideration by regulatory agencies. The method, Corrositex, is proposed as an alternative method to identify chemicals that are corrosive to skin. It uses no animals.