Phototoxicity testing
OECD TG 498
For this test, 3D reconstructed human skin models are incubated with three to five concentrations of the test material diluted in sesame oil and/or water. One set of models is exposed to UVA radiation, another set is kept in the dark (without irradiation) for the same period. After exposure all models are rinsed and incubated overnight. The next day, viability is assessed using the MTT test (colorimetric assay). If the difference between irradiated and non-irradiated models is less than 30 %, the test material has no phototoxic potential.
Prediction Model
| Mean tissue viability difference +UVA compared to -UVA |
In vivo Prediction |
| > 30% | phototoxic |
| < 30% | non-phototoxic |
Prediction of phototoxicity is supported if the (+UVA) induced reduction in tissue viability additionally shows a dose-response relationship.