title: Phototoxicity of narrowband ultraviolet (UV) B (311 nm) compared with broadband UVB in the photo hen's egg test.
abstract: BACKGROUND
  Broadband ultraviolet B (BB-UVB) is a well-established treatment option in dermatology. However, during the last decade BB-UVB has increasingly been replaced by narrowband UVB 311 nm (NB-UVB), especially in the therapy of psoriasis, atopic eczema and vitiligo. Several studies have indicated a better therapeutic response for almost all indications compared with BB-UVB.
  
  
  OBJECTIVE
  The aim of our study was to investigate the phototoxic effects of NB-UVB in comparison with BB-UVB in vivo.
  
  
  METHODS
  Therefore, we employed the photo hen's egg test (PHET), an established phototoxic model, based on the yolk sac blood vessel system of incubated hen's eggs. NB-UVB and BB-UVB dosages increasing from 30 up to 1200 mJ cm(-2) were applied on 17 test groups (each n = 12 eggs) and two unirradiated test groups served as controls. Twenty-four hours after irradiation we observed the following test parameters: lethality, membrane discoloration and haemorrhages.
  
  
  RESULTS
  Following our results, the lethal half dose (LD50) was 60 and 720 mJ cm(-2) for BB-UVB and NB-UVB, respectively. These LD50 dosages provoked severe membrane discoloration and haemorrhaging. Summarizing our results, the LD50 of NB-UVB was 12-fold higher than BB-UVB.
  
  
  CONCLUSIONS
  Interestingly, these findings are in good accordance with the literature, where the minimal erythema dose (MED) of NB-UVB in human skin is up to 14 times higher than the MED of BB-UVB. These results show that the PHET is a valid test model to evaluate the phototoxic effects of various UVB wavelengths. Moreover, our results indicate that regarding the investigation of phototoxic effects the PHET might serve as a model representative for human skin, which might reduce the extent of photoprovocation in humans in the future.
authors: Department of Dermatology, Porphyria Specialist Center, Heinrich Heine University Duesseldorf, Duesseldorf, Germany.
authors: P R
authors: PR
authors: Bafteh
authors: M
authors: M
authors: Siegesmund
authors: V
authors: V
authors: Kuerten
authors: N J
authors: NJ
authors: Neumann
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000528:radiation effects; D002642:Chick Embryo; D002645:Chickens; D004311:Double-Blind Method; D006470:Hemorrhage / Q000209:etiology; D011859:Radiography; D014466:Ultraviolet Rays / Q000009:adverse effects*; D015017:Yolk Sac / Q000000981:diagnostic imaging; D015053:Zygote / Q000528:radiation effects*