While I encourage everyone to use CFLs in order to conserve energy, here's a word of caution; DO NOT throw them in the trash when the bulbs burn out, they contain Mercury, a neurotoxin, which contaminates the soil and groundwater, and is harmful to our health.
Please read the instructions on the package label to determine how to dispose/recycle CFL bulbs properly.
The Environmental Protection Agency and some large business, including Wal-Mart, are aggressively promoting the sale of compact fluorescent light bulbs as a way to save energy and fight global warming. They want Americans to buy many millions of them over the coming years.
But the bulbs contain small amounts of mercury, a neurotoxin, and the companies and federal government haven't come up with effective ways to get Americans to recycle them.
NPR : CFL Bulbs Have One Hitch: Toxic Mercury