Spielmann, H., M. Balls, J. Dupuis, O. de Silva, W. Pape, R. Clothier, H-G. Holzhutter, F. Gerberick, M. Liebsch, W. Lovell, U. Pfannenbecker, J. Potthast, D. Sladowsky and W. Lovell. Successful Development, International Validation and Regulatory Acceptance of an In Vitro Phototoxicity Test: The 3T3 NRU PT Test. ATLA 27: 335. 1999.

Until now, an accepted protocol to test for photoirritation potential in vivo or in vitro did not exist. Initiated by ZEBET in 1991, the EU Validation Centre, ECVAM, and COLIPA, the European Cosmetic Toiletry and Perfumery Association, agreed on a joint EU/COLIPA programme for developing and validation in vitro phototoxicity tests. The first phase (1992-1993) was designed as a prevalidation study to identify in vitro tests for a validation trial under blind conditions. In the second phase (1994-1995), the most promising in vitro phototoxicity tests were validated with 30 carefully selected test chemicals in 11 laboratories in a blind trial, in which the 3T3 cell neutral red uptake phototoxicity (3T3 NRU PT) test was performed in nine laboratories. Results obtained with the 3T3 NRU PT test in the second phase were reproducible and the correlation between in vitro and in vivo data was very high even for chemicals insoluble in water. Therefore, in 1997, ECVAM, and in 1998, the EU Directorate Generals II (industry) and XI (environment), concluded “that the 3T3 NRU PT test is a well validated test that is ready to be used for regulatory purposes” and have officially submitted to the OECD a guideline for phototoxicity testing based on the 3T3 NRU PT test. Upon request of the Scientific Committee of Cosmetology of DG XXIV of the EU, ten UV filter chemicals were evaluated by four laboratories in a blind trial in the 3T3 NRU PT test. From the study on UV filter chemicals, participants and the management team concluded in 1998 that the UV filter chemicals from Annex VII of EU Directive 76/86/EEC are not phototoxic and that the 3T3 NRU PT test is a valid test correctly assessing the phototoxic potential of UV filter chemicals. During 1997 and 1998, the following expert committees of the EU accepted the 3T3 NRU PT test for regulatory purposes: ESAC, the ECVAM Scientific Advisory Committee, DG III, DG XI and the SCCNFP (Scientific Committee for Cosmetology and Non Food Products) of DG XXIV. A draft OECD Guideline for “In Vitro Phototoxicity Testing”, incorporating the standard protocol of the 3T3 NRU PT test, was submitted by DG XI officially on behalf of the EU to the OECD test guidelines programme in September of 1998.