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Gehrmann, W. H., Jamieson, D., Ferguson, G. W., Horner, J. D., Chen, T. C., & Holick, M. F. (2004). A comparison of vitamin d-synthesizing ability of different light sources to irradiances measured with a solarmeter model 6.2 uvb meter. Herpetological Review, 35(4), 361–364. 
Added by: Sarina (2009-04-05 17:22:10)   
Resource type: Journal Article
BibTeX citation key: Gehrmann2004
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Categories: Englisch = English
Keywords: Reptilien = Reptiles, Sehvermögen = Visual Perception, Vitamin D = Vitamin D
Creators: Chen, Ferguson, Gehrmann, Holick, Horner, Jamieson
Collection: Herpetological Review
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Abstract
A little more interesting, is another paper by Gehrman et al., 2004 (2) that reports on UV ability to react with 7-dehydrocholesterol (pro D3) to form the photoproducts of previtamin D3 (preD3) and vitamin D3 (vitD3) in glass ampules (unfortunately, not live reptiles). In it they verified the reciprocity law (Parrish et al., 1978) that states that the UVB effect on photoproduct formation is NOT from irradiance per se (i.e. rate of energy delivery as watts) but rather the total energy delivered during a given time period, which is the dose [dose (mJ/cm^2) = irradiance X time/1000]. Essentially, longer term exposure to a low irradiance UVB source will create the same amount of photoproduct as a short exposure to a higher irradiance UVB source. Next, the greater the concentration of UVB energy clustered around the MOST EFFECTIVE wavelength of 295nm, the greater the percent of photoproduct formed. Just because a bulb has UVB DOES NOT mean it will be effective at helping your animals produce vitD3, it has to have a good irradiance around 295nm. And for a rather interesting result, when comparing standard bulbs of Reptisun 5.0, ESU Reptile Desert 7% UVB, a Sylvania 350 black light and a Westron mercury vapor spot lamp 160W for photoproduct production effectiveness, for similar doses, the BEST source is the Sylvania 350 BL, followed by the Westron mercury vapor, and the two specialist bulbs a dead last. For similar doses, the Sylvania 350 BL yields about 3X the photoproduct of the Westron, and about 5X the photoproduct of the Reptisun and the ESU Reptile Desert. Keep in mind, however, that this study does NOT indicate what sources are best for a reptile, but given the findings of Ferguson et al., 2002, all these bulbs would be suitable, but the two reptile specific bulbs would have to be a lot closer to the animals to be as effective as the Sylvania and Westron for the same amount of time. In fact, given the irradiance of the Westron, it would be best kept at a good distance to avoid overexposure.
Added by: Sarina  
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