There are a couple health concerns that have been discussed in the media recently. Fortunately, the technical benefits of fluorescent lighting outweigh the risks.
The gas in fluorescent lamps is a mercury vapor, which is why some people are concerned about switching to fluorescents. However, the amount of mercury is small when compared to the amount of mercury released by coal-fired power plants. Since you’ll be changing out a 100 watt bulb for a (somewhere around) 25 watt bulb to get the same light, you reduce the generation needed at the power plant. (The US still generates most of its electricity from coal-fired plants.) Most researchers agree that switching to fluorescents will bring a net reduction in mercury emissions, and the EPA claims about a 2/3rd reduction in mercury emissions for changing a 60 watt incandescent to a 13 watt compact fluorescent.
Also, you can get lower mercury lamps by looking for TCLP compliant lamps. TCLP is a test the EPA has that involves crushing stuff up and see what leaches out.
Fluorescent lamps are classified as Universal Waste, which means you can’t throw it in the dump, but it doesn’t have to be handled like hazardous waste. It’s in the middle. You may or may not be able to recycle them in your area. The EPA has a page to help you figure out what’s available at their website: http://www.epa.gov/epawaste/hazard/wastetypes/universal/lamps/live.htm.
On a second matter, the current passing through the vapor generates UV (ultraviolet) rays, which are necessary to make the phosphor coating fluoresce. Much of the UV is shielded by the glass simply as a property of glass, nothing special is done to it. Some UV does come through, but it is a fairly small amount. “Full spectrum” fluorescent lamps are available, but I recommend you do not use them. They use older and less efficient phosphor coatings, they allow more UV through, and they are typically less efficient. There is also no definition of what “full spectrum” means, so you don’t know what you’re getting when you buy them.
