Validation of alternative toxicity test systems: lessons learned and to be learned

Area of Science:

• Toxicology
• In vitro testing
• Regulatory science

Background:

• Validation is crucial for the acceptance of in vitro toxicity tests.
• Current validation practices require critical assessment.
• Non-animal testing methods hold significant promise for toxicity assessment.

Purpose of the Study:

• To define validation in the context of in vitro toxicity testing.
• To discuss key aspects of the validation process.
• To highlight the need for reevaluation to advance non-animal testing.

Main Methods:

• Review of validation processes for in vitro toxicity tests.
• Discussion of interlaboratory validation schemes.
• Analysis of factors influencing validation, including data comparison and test selection.

Main Results:

• Identified critical elements in validation: test/chemical selection, laboratory participation, and in vivo/in vitro data comparison.
• Addressed challenges such as "false" results and the predictive value of cytotoxicity.
• Examined the validation of alternatives to specific animal tests, like the Draize eye irritancy test.

Conclusions:

• A comprehensive reevaluation of current validation practices is necessary.
• Realizing the full potential of non-animal toxicity tests depends on robust validation.
• Developing regulatory-accepted, valid alternative tests requires a thorough review of existing methodologies.