Validation of test methods

Validation is a rigorous scientific process where a large number of test items with a known effect on the endpoint of interest are being evaluated numerous times in several laboratories. All the data from a validation study must be available for independent review.

Formal validation for regulatory use

Solid evaluations of a new test method are crucial to gain trust and acceptance from those who will use it. Methods intended for regulatory risk assessment also have to undergo a formal validation. Formal validation is the key to regulatory utility of a test method. To be accepted by authorities in all OECD member countries, data needs to be generated by a test method that has been validated successfully and described in an OECD guideline.

OECD has published a guidance document on the validation process; OECD GD 34. It describes the validation steps in a modular way and some of the modules can be performed together.

EU Reference Laboratory ECVAM

The European Union Reference Laboratory for alternatives to animal testing, EURL ECVAM, is responsible for coordinating and undertaking validation studies for alternative methods for safety testing of chemicals in the EU. Any scientist can submit a test method to EURL ECVAM for participation in the validation program. EURL ECVAM will assess the regulatory potential and the efforts required for finalising the method. EURL ECVAM hosts a network of qualified laboratories, EU-NETVAL, that assist in data generation and also supports other tasks related to promoting the 3Rs.

A method that has been successfully validated can be submitted for adoption either as an OECD test guideline or as an international standard via ISO. This brings about a process: First, drafting of a guidance document or a standard, followed by review by international experts and, finally, voting on a finalized document by the members of the organisation that issues it.

The 3Rs Center’s resources on validation

The Swedish 3Rs Center has organized different activities over the years to contribute to the dissemination of information regarding validation of methods, both aimed at method developers and to the general scientific community. In the fall of 2021, the 3Rs Center organised a mini-series of webinars with focus on validation. They covered several parts of the process from development of a novel in vitro method to a validation study and the subsequent peer-review. During the spring of 2022, the 3Rs Center also released two infographics describing the development and validation of new research methods.

In addition to the informational efforts, the Swedish 3Rs Center has also contributed financially to the participation of Swedish representatives in expert groups for validation of test methods in several organisations within the EU, such as OECD and PEPPER.