"Compact fluorescent bulbs (CFLs) last far longer and use electricity more efficiently than conventional incandescent bulbs. Buy them if you can. They do contain a minuscule amount of mercury -- roughly four milligrams, or an amount the size of the period at the end of this sentence. (By comparison, a watch battery can contain up to 25 milligrams of mercury.) Hence, when a compact fluorescent bulb has reached the end of its long life, you should, if possible, take it to a hazardous-waste disposal facility rather than dumping it in the trash.
That said, the mercury in compact fluorescent bulbs currently does not pose a major problem -- and you know I don't take pollutants lightly. In municipalities such as Grist's hometown of Seattle, which is emphasizing conservation as a cost-cutting measure and pushing CFLs to the point of sending them free to ratepayers, there is an attendant concern about the solid-waste-disposal effects down the road. But let me emphasize: The tiny punctuation of mercury should not stop you from buying CFLs, any more than it stops you from wearing a watch.
One final note: Burning fossil fuels to generate electricity creates mercury pollution. Thus using compact fluorescent bulbs actually reduces mercury pollution, because CFLs use far less electricity than incandescent bulbs."
http://www.grist.org/advice/ask/2003/01 ... a-mercury/
"Is it true that CFLs contain mercury? Why and how much?
CFLs contain a very small amount of mercury sealed within the glass tubing - an average of 5 milligrams (roughly equivalent to the tip of a ball-point pen). Mercury is an essential, irreplaceable element in CFLs and is what allows the bulb to be an efficient light source. By comparison, older home thermometers contain 500 milligrams of mercury and many manual thermostats contain up to 3000 milligrams. It would take between 100 and 600 CFLs to equal those amounts.
There is currently no substitute for mercury in CFLs; however, manufacturers have taken significant steps to reduce mercury used in their fluorescent lighting products over the past decade.
Download the Environmental Protection Agency (EPA) fact sheet on Mercury in CFLs. (PDF, 17 KB)"
http://www.gelighting.com/na/home_light ... m#mercur...
"Q 2: I've heard CF bulbs have dangerous levels of mercury in them. What happens if I break one? Can I throw it in my garbage?
A 2: CF bulbs have about 4.0 milligrams of mercury in them to assist with starting. A troy ounce of mercury equals 31 grams, so 4.0 milligrams is about 1/1,000 of that amount. That amount of mercury is about the volume that would fill the size of the period at the end of this sentence. That amount of mercury is not dangerous in the home, but only becomes problematic when large amounts of CF bulbs are disposed in waste dumps.
If you accidentally break a CF bulb, the broken glass is more problematic than the mercury, as what mercury is left will be released into the air in a gaseous state."
http://www.seattle.gov/light/Conserve/R ... v5_lw2.htm