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Phototoxicity: 3T3 Neutral Red Uptake (NRU) Phototoxicity test

This assay is designed to assess cytotoxicity of test substances in the presence or absence of UV light. In this case, cytotoxicity is used as a proxy for acute phototoxicity, a chemically-induced skin irritation, requiring light for initiation of the effects.

The method is a cell based assay that uses 3T3 cells, with cytotoxicity assessed via neutral red uptake following exposure to the test substance (and light or not).

The test method has been approved for regulatory purposes to predict acute phototoxicity effects in animals and humans in vivo. It is the subject an OECD test guideline (No 432) and has been included in a number of EC regulations relating to the evaluation of chemical safety.

A number of validation studies have been carried out on the method and these have been reviewed by the EURL ECVAM Scientific Advisory Committee (ESAC) and published in peer-reviewed journals.

The results and full reports will be soon available on TSAR, the Tracking System for Alternative methods towards Regulatory acceptance.


The 3T3 Neutral Red Uptake (NRU) Phototoxicity test

Animal testing replacement

Validation studies and outcomes