The photosensitizing potential of compact fluorescent vs incandescent light bulbs.

Recently an article about the new energy-saving compact fluorescent light (CFL) bulbs appeared in Parade magazine [Rosenfeld, I. (2008) Parade Feb 3, 22]. Under the heading "Bright Lights, Bad Headache?" the writer states that "new research suggests some dangers" involving these lights because they are fluorescent and "can aggravate skin rashes in people with lups, eczema, dermatitis or porphyria." We measured the emission spectrum of a 14 W compact fluorescent bulb (with the same luminous flux as a 60 W incandescent bulb) and compared it to 60 W soft white incandescent and cool white fluorescent (CWF) bulbs. Our results clearly show that the spectral irradiance of the compact fluorescent bulb is similar to that of the CWF bulb; both exhibit sharp Hg emission lines at 365 nm (very weak), 404 nm (weak), 435 nm (moderate) and 543 nm (strong). In contrast, the emission of the incandescent bulb begins at 375 nm and then increases monotonically to above 750 nm. From their respective absorption spectra we calculated the potential photosensitization indices of protoporphyrin IX (PPIX; a prototypic porphyria skin photosensitizer) and riboflavin (a putative lens photosensitizer) vs 14 W compact fluorescent, CWF and 60 W incandescent bulbs. A higher photosensitization index would indicate a greater chance that the light/photosensitizer combination would cause photosensitization of the skin or eyes. We found that for PPIX and riboflavin the photosensitization index of the compact fluorescent bulb is less than half that of the 60 W incandescent bulb. These results suggest that substitution of a compact fluorescent bulb for an incandescent bulb of the same luminous flux should not increase the phototoxicity of skin porphyrins or lens riboflavin.