Alternative is the term traditionally used within the scientific community to describe the “3Rs” – methodologies to replace, reduce, or refine animal use in an existing test or procedure. Therefore, an alternative method can be another animal test that reduces animal use or that refines an existing method to lessen pain and suffering, or it can be a method that replaces animal use altogether. Since this section of our site addresses product safety and toxicity testing, the focus here will be on alternative methods intended for toxicity testing applications and that are being considered for acceptance by regulatory agencies.
A replacement alternative is a test method that has been endorsed by an appropriate authority as being capable of fully replacing an existing regulatory test method with a method that does not use live animals. A reduction alternative is a method that reduces the number of animals used. And a refinement alternative is a method that reduces animal suffering.
A new or alternative toxicity test method can be quite different from the existing animal test method, but it must provide the same or better prediction of human health effects for it to be accepted by regulatory agencies. To make this determination, representatives from government agencies, industry, and academia came together in the early 1990’s to establish criteria and processes for evaluating new toxicity test methods. Test method validation criteria were established by three organizations in the 1990s: the Organization for Economic Cooperation and Development (OECD), the European Centre for the Validation of Alternative Methods (ECVAM), and the U.S.’s Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM). Important terminology was defined as follows:
- Validation is "the process by which the reliability and relevance of a particular method or approach is established for a specific purpose."
- Reliability is the measure of a test’s reproducibility, which is the degree of variation in test results obtained when the same method is performed in the same lab over time, or performed in different laboratories or by different technicians.
- Relevance is the assessment of a test’s ability to correctly predict the biological effect of interest.
A validation study is conducted to obtain the data needed to assess the reliability and relevance of a new or revised toxicity test method. (It should be noted that the traditional Draize and LD50 tests were never subjected to a validation process). It is a large, expensive, and time-consuming process that takes place across several different laboratories. The data from the study are submitted to one of the validation centers, such as ECVAM or ICCVAM. The center, in turn, assesses the submitted data, and determines whether to move the method forward to peer review, where an assemblage of independent scientists evaluates the results and makes recommendations. ICCVAM or ECVAM’s advisory board then determines whether to recommend the test as scientifically valid for its intended purpose. If so, it is then called a validated method.
A validated method must still undergo further review before being accepted for use by a regulatory agency. Each agency makes its own determination of whether to accept data from the new method, and to what extent the new method can replace the existing regulatory test method (usually an animal test). This process is called regulatory acceptance.
To add to the complexity, each new method has specific limitations, and could be recommended for use as a partial or full replacement method, or as a screening assay that can be used as part of a test battery (a group of tests used to make a determination) or a tiered (or integrated) testing strategy (a group of tests and possibly other data used together in a specific scheme or sequence to make a determination). Therefore, potential users of a new method must study the recommendations and limitations of the method, even when it is considered to be validated.
Some companies have developed or adopted alternative test methods for internal use. These methods might be used to screen potential new ingredients, or to identify a less irritating formulation, as part of product development. If the data are not intended for submission to regulatory agencies, there is no need for the company to validate the test methods. Even so, these screening tests can considerably reduce animal use and can save a company time and money.