Light & Engineering Vol. 23, No. 4, pp. 41-46, 2015 Svetotekhnika No. 6, 2015, pp. 8-11 PHOTOBIOLOGY – PRESENTATION OF A BLUE LIGHT HAZARD IN VIVO EXPERIMENT ON THE RAT* Pierre Boulenguez1, Imene Jaadane2, Cristophe Martinsons1, Samuel Carrй1, Sabine Chahory3, and Alisio Torriglia2 1 Centre Scientifi que et Technique du Bвtiment, Grenoble, FRANCE, 2 Institut National de la Santй et de la Recherche Mйdicale, Paris, FRANCE, 3 Ecole Nationale Vйtйrinaire d’Alfort, Alfort, FRANCE, E-mail: Pierre.Boulenguez@cstb.fr ABSTRACT An animal experiment was conducted aiming at a better understanding of blue-light retinal toxicity. <...> Freely moving Wistar rats were exposed to intense, blue-rich light for up to eighteen hours. <...> Their retinas were analysed using transmission electron microscopy, Western Blot, immunofl uorescence, and Terminal transferase dUTP nick end labelling. <...> This paper details the dosimetry aspects of the experiment and summarizes the biological results. <...> Blue Light Hazard Blue light hazard (BLH) denotes an incompletely understood phenomenon by which radiations in the blue-end of the spectrum induce lesions in the layer of photoreceptors and retinal pigment epithelium (RPE). <...> Solid State Lighting Concerns over the BLH have intensifi ed because of the advent of “white-light” LEDs as general lighting service (GLS) sources. <...> A typical Indium gallium nitride (InGaN) LED indeed emits signifi cantly more blue-light per lumen than competing sources (Fig. 1). 1.3. <...> Exposure Limit Values The BLH action spectrum of Fig. 1 was determined through animal experiment. <...> The International Commission on Non-Ionizing Radiation Protection (ICNIRP) relied on these studies, and mostly on [3], to estimate that toxicity begins at a retinal dose of 20-30 J/cm2 of BLH-weighted radiation [4]. <...> Taking a substantial safety factor into account, a safe-dose threshold was set at 2.2 J/ cm2; indeed defi ning the guideline exposure limit value (ELV) for the BLH. <...> InGaN LED spectrum and BLH action spectrum to verify that any given source would not induce an excess of the ELV for the user [5]. <...> IN VIVO EXPERIMENT In this context, a new animal experiment was <...>