title: UV-A emission from fluorescent energy-saving light bulbs alters local retinoic acid homeostasis.
abstract: Worldwide bans on incandescent light bulbs (ILBs) drive the use of compact fluorescent light (CFL) bulbs, which emit ultraviolet (UV) radiation. Potential health issues of these light sources have already been discussed, including speculation about the putative biological effects on light exposed tissues, yet the underlying mechanisms remain unclear. We hypothesized photoisomerization of all-trans retinoic acid (at-RA), a highly light sensitive morphogen, into biologically less active isomers, as a mechanism mediating biological effects of CFLs. Local at-RA is anti-carcinogenic, entrains molecular rhythms and is crucial for skin homeostasis. Therefore, we quantified the impact of CFL irradiation on extra- and intracellular levels of RA isomers using an epidermal cell culture model. Moreover, a biologically relevant impact of CFL irradiation was assessed using highly at-RA-sensitive human neuroblastoma cells. Dose-dependent conversion of extra- and intracellular at-RA into the biologically less active 13-cis-isomer was significantly higher in CFL vs. ILB exposure and completely preventable by employing a UV-filter. Moreover, pre-irradiation of culture media by CFL attenuated at-RA-specific effects on cell viability in human at-RA-sensitive cells in a dose-dependent manner. These findings point towards a biological relevance of CFL-induced at-RA decomposition, providing a mechanism for CFL-mediated effects on environmental health.
authors.affiliation: Clinical Neurobiology, Department of Psychiatry, Charité, University Medicine Berlin, CBF, Eschenallee 3, 14050 Berlin, Germany. julian.hellmann@charite.de.
authors.forename: Julian
authors.initials: J
authors.lastname: Hellmann-Regen
authors.forename: Isabella
authors.initials: I
authors.lastname: Heuser
authors.forename: Francesca
authors.initials: F
authors.lastname: Regen
mesh_terms: D000970:Antineoplastic Agents / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007536:Isomerism; D008027:Light; D014212:Tretinoin / Q000032:analysis / Q000737:chemistry* / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D000970:Antineoplastic Agents; D014212:Tretinoin