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Study: Bulb Coating Defects Leak UV

Tuesday, August 7, 2012

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Widespread chipping and cracking in the coating of today’s compact fluorescent bulbs is giving users a significant—and potentially damaging—dose of UV exposure, researchers at Stony Brook University have found.

 CFL bulb via Shutterstock

 CFL bulb via Shutterstock

The phosphor coating on the twisty new-generation bulbs “is brittle and has trouble making the tight bends required to make these bulbs compact,” the lead researcher says.

“Measurements of UV emissions from these bulbs found significant levels of UVC and UVA…, which appeared to originate from cracks in the phosphor coatings, present in all bulbs studied,” reports the team led by Miriam Rafailovich, a Professor of Materials Science and Engineering and Director of the university's Garcia Center for Polymers at Engineered Interfaces.

How significant was the exposure? Skin damage from the inadequately coated compact fluorescent lights (CFLs) “was consistent with damage from UV radiation,” the team reported July 20 in the journal Photochemistry and Photobiology.

Looking for Bald Spots

Millions of facilities and homes have made the switch from incandescent bulbs to the twisty-looking compact fluorescents. Inspired by a European study on light sensitivity, the Stony Brook researchers looked into the potential impact of UV exposure from the new bulbs on healthy human skin tissue.

After buying a wide array of CFL bulbs from retail stores around Long Island, NY, the team measured each bulb for levels of UV emissions and examined each for signs of cracking in the phosphor coating that is applied to the narrow glass tubing.

The coating is designed to enhance the bulb's luminescence capacity while absorbing UV radiation that would otherwise be emitted. The researchers warn that if the bulb's surface area is riddled with "bald" spots, UV protection is lost.

Brittle Coating, Tight Turns

The result: Cracked coating on every bulb, regardless of manufacturer or brand, was found to emit "significant" levels of both UVC and UVA rays, the team reported.

The bulbs "have cracks in the phosphor coating, probably due to the fact that the coating is brittle and has trouble making the tight bends required to make these bulbs compact," said Rafailovich. "As a result, we observed, by eye, defects in nearly all the bulbs that we studied."

The resulting effect on healthy skin was "consistent" with the damage typically caused by the sun, the team found. By contrast, exposure to incandescent bulbs of similar strength inflicted no skin cell damage.

Switched on Fluorescents

Compact fluorescents are quickly replacing incandescent bulbs by the millions.

The U.S. National Institutes of Health notes that the newer technology uses about 75 percent less energy than standard incandescents, and it will soon be illegal to sell incandescent bulbs for home use in the U.S.

Rafailovich warns, however, that the new-generation bulbs "are fragile, the phosphor is easily damaged, and possibly dangerous amounts of UV are emitted.”

“Therefore, it's best not to use these bulbs at close range—less than a couple of feet—or look directly at them,” she said. “To be safe, they should be used behind a glass cover, or kept at a distance of several feet or more."

The findings came as a surprise, Rafailovich told one reporter.

"You should not need suntan lotion to protect you from indoor lighting," she said.


Tagged categories: Coatings technology; Cracking; Paint defects

Comment from Gary Burke, (8/8/2012, 8:06 AM)

nice to see yet another source of a possible cancer causer and the alternative is illegal use of incandescent bulbs!

Comment from William Feliciano, (8/8/2012, 12:25 PM)

I find it very hard to believe that the companies making these bulbs are unaware of this problem - i'm certain that they have QC people onboard, especially coatings folks. Very very irresponsible...wouldn't be surprised if this winds up in some sort of class action suit.

Comment from Mark Baumgartner, (8/9/2012, 1:49 AM)

Wow real nice. I use these every day and so do my kids. What is the coatings industry doing about it?

Comment from Mark Baumgartner, (8/9/2012, 1:51 AM)

Just make sure you use shades or glass covers.

Comment from John Fauth, (8/9/2012, 8:31 AM)

Let's see if I have this correct... broken bulbs are (literally) hazardous waste due to mercury contamination; using the bulbs is a UV hazard (increased incidence of skin cancer?); and putting billions (again, literally) of these into our landfills will result in mercury leeching into the ground water.... yeah, I can understand why environmentalists and the government would require their use.

Comment from Richard McLaughlin, (8/9/2012, 9:35 AM)

William, don’t hold your breath on that class action going anywhere. Most of these bulbs are made in China, so the ability to sue is slim to nil. As for quality control on items imported from China, well, that can be a hit or miss thing. Some companies there do a very good job, but most don’t.

Comment from John Fauth, (8/9/2012, 9:57 AM)

Richard, although most of the CFL's are indeed made in China, they are marketed and sold in the US by our traditional brand name manufacturers (GE, Phillips, etc). The attorneys will have a field day.

Comment from John Fauth, (8/9/2012, 9:59 AM)

P.S. - This is a great example of regulation exporting US jobs overseas. Traditional incandescent bulbs are made here in the US. As noted by others, CFL's are largely made in China.

Comment from M. Halliwell, (8/9/2012, 10:42 AM)

Hmmmm....LED lights, anyone?

Comment from Tom Schwerdt, (8/22/2012, 4:18 PM)

"significant" levels can mean anything. Give me numbers. Compare it to noonday sun in August in Austin, TX, or some other benchmark.

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