Alternatives to Animal Testing

Introduction

Scientists often study the effects of drugs and chemicals on animals before they deem them safe for humans.

When possible, they try to perform these toxicology tests using biochemical or cell-based (in vitro) systems instead of with animals such as mice. For example, researchers successfully created in vitro methods to identify severe eye irritants and substances that could cause allergic contact dermatitis. ¹  However, the development of in vitro tests that can reliably identify chemical hazards resulting in cancer or birth defects is more difficult because of the complexity of the biological processes involved.

Computer programs with advanced systems based on large chemical databases can predict a chemical's toxicity, reducing the need for animal testing in some situations.

The concept of replacing, reducing, or refining replacing, reducing, or refining animal use in research and testing was first described more than 60 years ago ² and is commonly referred to as 3Rs:

• Replacing: A test method that substitutes traditional animal models with non-animal systems such as computer models or biochemical or cell-based systems, or replaces one animal species with a less developed one (for example, replacing a mouse with a worm).
• Reducing: A test method that decreases the number of animals required for testing to a minimum while still achieving testing objectives.
• Refining: A test method that eliminates pain or distress in animals, or enhances animal well-being, such as by providing better housing or enrichment.

Test methods that incorporate the 3Rs are referred to as new alternative methods.

Under U.S. law and policies, scientists must consider alternative methods before using animals for toxicology research and testing.

• The Animal Welfare Act requires that committees in facilities conducting animal research and testing approve proposed animal use and ensure that alternatives are used where appropriate.
• The Public Health Service Policy on Humane Care and Use of Laboratory Animals, which applies to NIH and other federal agencies under the U.S. Public Health Service, requires that research proposals justify animal use and the specific procedures.

The NIH Revitalization Act of 1993 directed the National Institutes of Health (NIH) to support research to replace, reduce, and refine animal use in biomedical research, and to develop and validate alternatives to animal use for acute and chronic safety testing. Activities carried out under this Act led to the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) Authorization Act of 2000. ICCVAM, comprised of representatives of U.S. federal agencies that use or generate toxicity testing information, coordinates activities within the federal government relevant to new test method evaluation, acceptance, and use.

What Is NIEHS Doing?

NIEHS, an ICCVAM member agency, supports development of alternative methods to animal testing in its in-house research and through grants to external researchers and small businesses.

The National Toxicology Program (NTP) Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) conducts many of these research activities, including:

• Conducting and publishing analyses and evaluations of data from new, revised, and alternative testing approaches.
• Providing information to test method developers, regulators, and regulated industry through its website and other communications.
• Organizing workshops and symposia on topics of interest.
• Providing bioinformatics and computational toxicology support to NTP and NIEHS projects, especially those related to Tox 21, a program from the NTP in collaboration with other agencies that researchs, develops, evaluates, and translates innovative test methods to better predict how substances may affect humans and the environment.

NICEATM scientists publish scientific papers describing activities relevant to alternative methods development. These activities include evaluating new methods and approaches, and developing tools and compiling reference data for use by test method developers. They also report on related workshops, review alternative methods, and comment on testing status.

NICEATM supports the Interagency Coordinating Committee on the Validation of Alternative methods (ICCVAM), which evaluates and prepares recommendations on test methods proposed for regulatory use. Test methods recommended by ICCVAM and accepted by U.S. and international regulatory authorities include ways to assess hazards for eye and skin irritation, acute toxicity, and skin sensitization.

Further Reading

Stories from the Environmental Factor (NIEHS newsletter)

• Future Challenges in Reducing Animal Testing Assessed by Panel (November 2023)
• Impact of Variability in Animal Test Data Discussed by Kleinstreuer (January 2022)
• Agencies Advised on Reducing Animal Testing, Embracing Alternatives (November 2021)
• New Chemical Testing Approach Will Help to Replace Animal Use (August 2021)
• Animal Replacement Accomplishments Draw Broad Interest (July 2021)
• Computational Toxicology Featured in Special Journal Issue (March 2021)
• Organs-on-a-chip for COVID-19 Research Groups Led by NTP Center (March 2021)
• Department of Veterans Affairs Joins Effort to Reduce Animal Testing (December 2020)
• Nonanimal Safety Testing Requires Data Quality, Measures of Success (October 2020)
• Animal Testing Alternatives Advanced by 16 Government Agencies (September 2020)
• Reduction in Animal Testing Celebrated at National Meeting (July 2020)

Additional Resources

• A Strategic Roadmap for Establishing New Approaches to Evaluate the Safety of Chemicals and Medical Products in the United States
• Interagency Coordinating Committee on the Validation of Alternative Methods
• NTP Interagency Center for the Evaluation of Alternative Toxicological Methods
• Scientific Advisory Committee on Alternative Toxicological Methods (SACATM)
• What is Bioethics?