- © 2007 Canadian Medical Association
The mythology is certainly pervasive: fluorescent lighting variously causes carcinomas, breast cancer, high blood pressure and other cardiovascular diseases, headaches, eye strain, fatigue, depression and even sexual dysfunction. Break a compact fluorescent light bulb and you might as well be mainlining mercury or, at a minimum, should be calling in experts in white suits and helmets to clean up the toxic waste zone that once was your bedroom.
Yet, health and lighting experts say that there's no valid scientific evidence to support any of the above propositions and that there are few, if any, health consequences that will result from government moves to outlaw incandescent light bulbs. In the interest of energy efficiency and reducing greenhouse gas emissions, the province of Ontario has announced it will ban bulbs by 2012, following the lead of Australia and Nunavut.
“As far as health goes, outside of the remote possibility of some sub-populations that we haven't identified, I'd say there aren't any consequences,” says Dr. Jennifer Veitch, senior research officer in the Indoor Environment Research Program at the National Research Council Institute for Research in Construction.
Even clean-up and disposal of broken fluorescent bulbs shouldn't pose an immediate health risk, provided that recommended clean-up procedures (see Box 1) are followed, says Rennsselaer Polytechnic Institute Lighting Research Centre Senior Research Scientist Dr. John Bullough. “You don't want to run over and sniff it up.”
The average compact fluorescent bulb contains 5 milligrams of mercury, as compared with 500 in older household thermometers. “It's true that if you break a fluorescent lamp, you don't want to be breathing the elemental mercury. It's not desirable. However, there's a lot less mercury in a fluorescent lamp today than there used to be,” says Veitch. “Your bigger risk, if you broke the lamp, is you'd have a lot of slivers of broken glass around.”
Both Veitch and Bullough say the more problematic issue surrounding mercury and compact fluorescent bulbs lies in their disposal. The mercury in bulbs dumped at landfills can leach out into the water supply, be converted into a highly toxic form called methylmercury and work its way back into the food chain. Ideally, the mercury should be recycled, Bullough says. But there are other environmental trade-offs that must to be factored into the long-term equation when considering bulb disposal, he adds. A power plant emits 10 milligrams of mercury to produce the electricity needed to run an incandescent bulb, compared with 2.4 milligrams for a compact fluorescent, so the net effect of using fluorescent bulbs is still an overall reduction in environmental mercury.
When compact fluorescent bulbs became widely available in the mid-1980s, several studies were published suggesting there was an elevated melanoma risk, but those have since been discredited, Veitch adds. “With respect to cancer risk, there is no good evidence that anyone need fear from the use of compact fluorescents or regular fluorescent tubes. There's no risk for melanoma from either of those lamp types.”
Bullough says the average person would have to go out of their way to find a special compact fluorescent bulb that emits a large amount of short-wave, ultraviolet radiation and then spend untold hours under the lamp trying to induce sunburn before there would be anything like a risk of skin melanoma. “You'd really have to work at it.”
Experts also say that other health effects often anecdotally associated with fluorescent lights, such as headaches, eye strain and depression, are similarly difficult to quantify, scientifically.
Earlier versions of fluorescent bulbs operated at much lower frequencies (120 Hertz) compared with newer ones (typically, 30 000–40 000 Hertz) and used a different ballast (magnetic rather than electronic) to stabilize the current in the circuit, causing some people to perceive a flicker in the lighting and experience headaches or eye strain. But newer bulbs are “way beyond the ability of the nervous system to detect any kind of oscillation in the output,” Veitch says.
Still, “it's possible there are sub-groups, of which we're not aware, that could be particularly sensitive” to fluorescent lighting, she adds.
Dr. Julia Knight, senior investigator and leader of the Prosserman Center for Health Research at the Samuel Lunenfeld Research Institute associated with the University of Toronto's Mount Sinai Hospital, says there may be similar remote possibilities and uncertainties related to the impact of fluorescent lighting on circadian rhythms and the production of the hormone melatonin. Studies have linked disruption of the melatonin cycle with the growth rate of malignant tumors. Limited evidence suggests the cycle is disrupted by exposure to very bright light from the blue end of the visual spectrum, Knight says. As for the difference between incandescent and fluorescent lighting: “I'm not sure we know enough to be sure, but I'm not concerned about it.”
Veitch, a psychologist by training, says that some people will be far more distressed by “aesthetic” effects resulting from a shift to fluorescent, as opposed to incandescent, bulbs. The 2 types are weighted differently towards differing parts of the visual spectrum, so colours will appear slightly different, while the light that is generated will diffuse differently and have a differing “directionality,” leading some people to believe that fluorescents are less bright, even though they're emitting the same amount of light.
Yet, even then, there should be no ill-consequence in terms of eye strain, and no impact on activities like reading, Veitch adds. “If there is, then people may want to choose a slightly higher wattage of CFL [compact fluorescent lamp] but even if they do that, they'll still be saving energy.”