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The latest twist on compact fluorescent bulbs: They may be UV emitters

Compact fluorescent bulbs (often referred to as CFLs) burn less energy per unit of emitted light. That's something pretty much everbody can agree on. But that's about it.

As some readers may know, the U.S. government effectively banned the production of incandescent bulbs going forward by mandating energy-consumption standards no incandescent bulb is likely to meet. At least for the short term, this has tilted the playing field in favor of CFLs.

You either love the temperamental twisted tubes, presumably because they're energy efficient, or hate them for any of a number of reasons. First, they're expensive. Worse, because they contain mercury, CFLs have to be disposed of carefully - and should you, heaven forbid, drop one and have it smash into smithereens on the floor, the Environmental Protection Agency says you are supposed to open the windows immediately and clear the room.

I've got one in my kitchen. When I turn it on, it takes a while to warm up - and when it finally does, the light it gives off is, well, dirty. It's depressing. I hate it.

Now, it turns out, there could be a medical reason to hate CFLs too: A recent study in the journal Photochemistry and Photobiology by researchers at the State University of New York, Stony Brook, indicates that, despite advocates' claims to the contrary, these bulbs give off significant amounts of ultraviolet light, namely in the UVA and UVC range. The SUNY investigators explain that stresses introduced in the bulbs' X-ray-absorbing coatings during the tubes' manufacture cause minute cracks or lapses in those coatings:

Closer examination of some of these commercially available bulbs showed multiple defects in their coating, thus allowing UV-light emission. . . . These data are particularly disturbing as the UVC emission is even larger than ambient sunlight on a mountain.

To see if these emissions were physiologically harmful to human skin, the researchers used various biological assays on two kinds of human skin cells: keratinocytes and dermal fibroblasts. For example, the cells were exposed to CFLs so that they got the same UV doses a person's skin would get from the bulbs after 45 hours at the typical working distance from a desk lamp. The damage to the cells was noticeable and was similar to the kind that occurs in the aging process. (It took only five hours at that distance from a CFL to get UV exposure exceeding recognized safety standards, the scientists noted.)

Ironically, adding either of two forms of titanium oxide (the chief UV-absorbing component of commercial sunscreens) to the skin cells made the damage that CFLs inflicted on them even worse.

Photo by Nioxxe

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