that are phototoxic in vivo after systemic application and distribution to the skin, as well as compounds that could act as phototoxicants after topical application to the skin can be identified by the test. The reliability and relevance of the 3T3 NRU PT have been evaluated and has been shown to be predictive when compared with acute phototoxicity effects in vivo in animals and humans." Taken with permission from During drug development Several health authorities have issued related guidance documents, which need to be considered for drug development: ICH (International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use) M3(R2) "Guidance on Nonclinical Safety Studies for the Conduct of Human Clinical Trials and Marketing Authorization for Pharmaceuticals" S9 "Nonclinical Evaluation for Anticancer Pharmaceuticals" S10 "Photosafety Evaluation" EMA (European Medicines Agency) "Note for Guidance on Photosafety Testing" (revision on-hold) "Question & Answers on the Note for Guidance on Photosafety Testing" FDA (U.S. Food and Drug Administration) MHLW/PMDA (Japanese Ministry of Health, Labour and Welfare / Pharmaceuticals and Medical Devices Agency) Phototoxicity in light microscopy When performing microscopy on live samples, one needs to be aware that too high light dose can damage or kill the specimens and lead to experimental artefacts. This is particularly important in confocal and superresolution microscopy. See also Photodynamic therapy References External links In Vitro Phototoxicity Test 3T3 NRU Phototoxicity Test Toxicology