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Environmental Factor

January 2011

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New green safety testing methods available to identify ACD

January 2011

NIEHS has endorsed two new alternative safety-testing methods to determine if chemicals and products may cause allergic skin reactions, also known as allergic contact dermatitis (ACD). Skin diseases are the most common occupational disease category, and allergic reactions account for a large percentage of these cases.

The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM)( recently evaluated and recommended the new methods, which are versions of the murine local lymph node assay (LLNA).

NIEHS/NTP Director Linda Birnbaum, Ph.D., endorsed the ICCVAM recommendations in a recent memorandum, in which she noted, "NIEHS and the NTP( will promote and encourage use of the standard and nonradioactive versions of the LLNA for assessing the allergic contact dermatitis potential of chemicals and products."

The two new green technology methods provide both environmental and animal welfare advantages, compared to traditional test methods.  Since these methods do not use radioactive reagents, they avoid the generation of radioactive waste and can be used by laboratories that are not licensed to use radioactive reagents. They also provide for improved animal welfare and use up to 50 percent fewer animals than traditional test methods.

ICCVAM and the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) conducted a comprehensive technical evaluation of the scientific validity of the two non-radioactive methods - the LLNA: 5-bromo-2-deoxyuridine-ELISA (LLNA:BrdU-ELISA), and the LLNA: Daicel Adenosine Triphosphate (LLNA:DA). ICCVAM concluded that the accuracy and reliability of the two methods support their use for safety and hazard assessments.

Protocols for the recommended LLNA methods and other ICCVAM-recommended test methods are available on the test method protocols page of the NICEATM-ICCVAM website.

The U.S. Public Health Service Policy on Humane Care and Use of Laboratory Animals and Animal Welfare Act regulations require consideration of alternative methods that may reduce, refine, or replace animal use prior to the approval of procedures involving animals, and their use when determined scientifically appropriate. Since the new testing methods do not involve pain and distress compared to traditional testing methods, they will need to be considered and used for safety studies when determined appropriate.

Birnbaum has asked the NIEHS Institutional Animal Care and Use Committee, which oversees and evaluates all aspects of the NIEHS animal care and use program, to ensure that these alternative methods are always considered whenever applicable. Appropriate consideration and use of the methods will minimize animal use and provide for improved animal welfare while allowing investigators to conduct sound scientific research supporting the protection of human health.

Information on the NICEATM-ICCVAM evaluation of the nonradioactive LLNA methods is also available on the NICEATM-ICCVAM website(

Background of the LLNA

The current recommendations are the latest from a series of evaluations of the LLNA by NICEATM and ICCVAM. In October 2009, ICCVAM forwarded recommendations to federal agencies for LLNA performance standards and an updated LLNA protocol that further reduces animal use by up to 50 percent. Based on a review of recent data, ICCVAM has also recommended that the LLNA can be used for testing nearly all chemicals and products, including pesticide formulations. NICEATM and ICCVAM proposed new and updated international test guidelines for the new LLNA versions that have now been adopted by the 33 member countries of the Organisation for Economic Co-operation and Development. NICEATM and ICCVAM are also currently evaluating several in vitro and in chemico methods for their potential to further reduce and eventually replace the need for animals for allergic contact dermatitis safety testing.

NICEATM provided scientific support and coordination for the ICCVAM Interagency Immunotoxicity Working Group (IWG) that evaluated the new LLNA versions and applications. The IWG is co-chaired by Abigail Jacobs, Ph.D., of the U.S. Food and Drug Administration (FDA) and Joanna Matheson, Ph.D., of the U.S. Consumer Product Safety Commission (CPSC). It includes scientists from the CPSC, the Environmental Protection Agency, FDA, NIEHS, and the National Institute for Occupational Safety and Health. NIEHS scientists Dori Germolec, Ph.D., William Stokes, D.V.M, and Warren Casey, Ph.D., D.A.B.T., contributed to the ICCVAM recommendations. Stokes is director of NICEATM and executive director of ICCVAM.

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