UV filter chemicals

/Tag:UV filter chemicals

A Study on UV Filter Chemicals from Annex VII of European Union Directive 76/768/EEC, in the In Vitro 3T3 NRU Phototoxicity Test

Horst Spielmann, Michael Balls, Jack Dupuis, Wolfgang J. W. Pape, Odile de Silva, Hermann-Georg Holzhütter, Frank Gerberick, Manfred Liebsch, Will W. Lovell and Uwe Pfannenbecker

In 1996, the Scientific Committee on Cosmetology of DGXXIV of the European Commission asked the European Centre for the Validation of Alternative Methods to test eight UV filter chemicals from the 1995 edition of Annex VII of Directive 76/768/EEC in a blind trial in the in vitro 3T3 cell neutral red uptake phototoxicity (3T3 NRU PT) test, which had been scientifically validated between 1992 and 1996. Since all the UV filter chemicals on the positive list of EU Directive 76/768/EEC have been shown not to be phototoxic in vivo in humans under use conditions, only negative effects would be expected in the 3T3 NRU PT test. To balance the number of positive and negative chemicals, ten phototoxic and ten non-phototoxic chemicals were tested under blind conditions in four laboratories. Moreover, to assess the optimum concentration range for testing, information was provided on appropriate solvents and on the solubility of the coded chemicals. In this study, the phototoxic potential of test chemicals was evaluated in a prediction model in which either the Photoirritation Factor (PIF) or the Mean Photo Effect (MPE) were determined. The results obtained with both PIF and MPE were highly reproducible in the four laboratories, and the correlation between in vitro and in vivo data was almost perfect. All the phototoxic test chemicals provided a positive result at concentrations of 1µg/ml, while nine of the ten non-phototoxic chemicals gave clear negative results, even at the highest test concentrations. One of the UV filter chemicals gave positive results in three of the four laboratories only at concentrations greater than 100µg/ml; the other laboratory correctly identified all 20 of the test chemicals. An analysis of the impact that exposure concentrations had on the performance of the test revealed that the optimum concentration range in the 3T3 NRU PT test for determining the phototoxic potential of chemicals is between 0.1µg/ml and 10µg/ml, and that false positive results can be obtained at concentrations greater than 100µg/ml. Therefore, the positive results obtained with some of the UV filter chemicals only at concentrations greater than 100µg/ml do not indicate a phototoxic potential in vivo. When this information was taken into account during calculation of the overall predictivity of the 3T3 NRU PT test in the present study, an almost perfect correlation of in vitro versus in vivo results was obtained (between 95% and 100%), when either PIF or MPE were used to predict the phototoxic potential. The management team and participants therefore conclude that the 3T3 NRU PT test is a valid test for correctly assessing the phototoxic potential of UV filter chemicals, if the defined concentration limits are taken into account.
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The Use of Human Keratinocytes in the EU/COLIPA International In Vitro Phototoxicity Test Validation Study and the ECVAM/COLIPA Study on UV Filter Chemicals

Richard Clothier, Angie Willshaw, Helen Cox, Michael Garle, Helen Bowler and Robert Combes

The EU/COLIPA in vitro phototoxicity study involved the testing of 30 chemicals in Phase II, and the ECVAM/COLIPA study on UV filter chemicals involved the testing of 20 chemicals, for which in vivo human and/or animal data were available. Primary human keratinocytes, from four separate male donors, were not found to be sensitive to the 5J/cm2 UVA produced by the SOL500 lamp when assayed by using the neutral red uptake endpoint, as employed with the 3T3 cells used in these international interlaboratory validation studies. The primary human keratinocytes tested in one laboratory alongside the 3T3 fibroblasts gave consistent indications of phototoxicity with all the phototoxicants tested in the Phase II and UV filter studies. The one exception was bithionol, which was predicted to be non-phototoxic in both studies. None of the non-phototoxic chemicals resulted in a positive reaction with the Photoirritation Factor (PIF) version of the prediction model. However, when the Mean Photo Effect (MPE) prediction model version was applied (with a cut-off point of 0.1), one sunscreen agent, octyl salicylate, was deemed to have phototoxic potential. The entire set of negative rated chemicals included in Phase II and in the UV filter study were also rated as non-phototoxic by the MPE prediction model.
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