Scientific American ^ | July 25, 2012
SKIN RISK: A new study finds that damaged compact fluorescent lightbulbs can emit harmful ultraviolet light capable of damaging skin cells.
The curlicue compact fluorescent lamps (CFLs) oft touted as an Earth-friendly alternative to standard incandescent bulbs may cause skin damage, according to a new study by researchers at Stony Brook University.
The bulbs are already known to pose hazards from using mercury, a toxic element, though in very small quantities, as lighting manufacturers are quick to point out. Regulations in parts of the United States and in the European Union limit mercury to 3.5 milligrams per bulb, with the limit dropping to 2.5 mg next year.
Now researchers have found that ultraviolet radiation seeping through CFLs may damage skin cells. Miriam Rafailovich, a professor of materials science and engineering at Stony Brook, led the research after reading an article in an Israeli newspaper that reported a spike in skin cancer on a communal farm when residents switched to fluorescent bulbs.
"In the past two years some disturbing reports have surfaced mostly in the European Union literature, which indicate that exposure to CFL bulbs might be responsible for exacerbating certain skin conditions, such as photodermatoses and skin cancer in humans," says the paper, published last month in the journal Photochemistry and Photobiology.
The issue comes from how CFLs are designed. Fluorescent lamps, large and compact, work by using electricity to excite mercury vapor inside the bulb. The excited vapor then emits invisible ultraviolet light that is absorbed by the bulb's phosphor coating. In turn, the coating re-emits the energy as visible light.
But researchers found UV light leaks more from CFLs compared to standard fluorescent tubes because the small diameter of the glass coupled with its twists and turns creates more spaces where the phosphor coating chips away, letting more UV light escape.
Past studies indicated that UV emissions from CFLs could harm previously damaged tissue and worsen chronic skin conditions, but researchers were curious about what these lamps do to healthy skin. To find out, the scientists studied two types of skin cells: keratinocytes, which make up 95 percent of the outermost layer of skin, and dermal fibroblasts, which form the connective tissue underneath.
Using CFL bulbs from different manufacturers purchased from retailers on Long Island, the team exposed cultured skin cells in a petri dish to the bulbs mounted in a desk lamp from different distances for varying periods. The team measured how much UV light was emitted and then assessed how the cells responded.
"All of them had some [UV emissions], but some were a lot worse than others," Rafailovich said of the bulbs. She noted that colored fluorescent party bulbs had lower UV emissions because the flexible color coating helped protect the phosphor layer.
Avoid close contact, researchers say
UV light comes in three varieties: UVA, UVB and UVC. The researchers tested the bulbs for UVA and UVC emissions. In skin cells, UVA creates reactive oxygen, which can damage their inner workings, and penetrates further into skin. Outdoors, people are typically exposed to UVA and UVB.
UVC, on the other hand, is usually scattered away by air, so we aren't usually exposed to it in sunlight. However, close to its source, like a CFL, UVC damages DNA.
"We saw significant amounts of UVC [from CFLs], which is not what you see in the atmosphere," said Rafailovich.
Under CFLs, the experiments showed cells stopped growing and changed shape. Dermal fibroblasts suffered worse than keratinocytes, since they are usually not exposed to light. This indicates these bulbs can damage skin in several layers.
Rafailovich explained that at close range, around a foot or so, CFL exposure is "the equivalent of sunbathing at the equator." This may not be cause for alarm for those who have CFLs mounted in ceiling fixtures, but it should be a concern with desk or table lamps. The researchers recommend avoiding CFLs at close range and placing them behind glass barriers or enclosures.
However, there are alternatives in energy-efficient lighting now that LEDs are dropping in price and manufacturers are making more efficient versions of incandescents.
"LED and incandescent light bulbs have no emission in UV range; therefore, they do not pose any risk," said Tatsiana Mironava, one of the report's co-authors and adjunct faculty in the Department of Chemical and Molecular Engineering at Stony Brook, in an email.
Fluorescent bulbs often use less than a quarter of the energy of comparable filament bulbs, making them appealing to consumers who want to lower their energy bills. Though the bulbs have been around since the 1940s, recent price drops, government incentives and legislation phasing out sales of old inefficient lighting have helped CFLs illuminate many more homes and businesses.
The U.S. Department of Energy has strongly advocated CFL use under its Energy Star program, spending $252 million in 2010 to increase CFL adoption.
