Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

No UVB from tungsten filament incandescent lamps

William H. Gehrmann, PhD, Bulletin of the ARAV, 1992, 2(2):5

Occasionally I have noticed advertisements in regional herp society bulletins, dealer lists and pet trade literature for incandescent bulb or reflector type full spectrum lamps that purportedly promote ultraviolet (UV) synthesis of vitamin D3, strong bones, easier eggshell formation and in general the improvement of reptile health. They may or may not be described as imported from Finland and may be referred to as Chromalux. A similar lamp is manufactured by Duro-Test Corp. and marketed as Neo-White. General Electric, Phillips and Sylvania do not produce this kind of lamp at this time. [NB: Note that this article was written before Energy Savers Unlimited, Inc.'s "Reptile" line of "full spectrum" "coated with rare earth neodymium" lights came on the market. -Melissa Kaplan.]

Study of the spectral power distribution (SPD) of these lamps indicate that they are not "full spectrum" in the sense that distribution of energy in the different color bands is not comparable to that found in natural light. Furthermore, the SPD shows that while there is a small amount of UV A (not related to vitamin D3 synthesis), there is no UV B. What makes these lamps different from common incandescent lamps? The glass envelop contains the element neodymium which selectively filters out most of the yellow portion of the visible spectrum and thus the lamp produces a light which appears "whiter."

Although these lamps do not emit UV B, they are not harmful when used for providing visible light and heat. I have reared hatchling whiptail lizards (Cnemidophorus gularis) under these lamps as effectively as under common incandescent reflector lamps but in both cases, adequate vitamins and minerals were dietarily provided. The whiter light emitted from neodymium lamps is therefore for the benefit of the viewer in terms of color rendition. Whether the difference in cost between a common incandescent and a neodymium lamp is worth the price is a non-biological judgment.