Barbara: Mercury is a relatively nonreactive liquid at room temperature, and it easily vaporizes. Through a complex environmental cycle, not yet fully understood by scientists, aquatic bacteria transform atomic Hg into highly toxic ions such as methyl mercury (CH3Hg+). With a nonpolar methyl group (–CH3), CH3Hg+ is fat-soluble. When ingested by fish, it is stored in their muscles and moves up the food chain. In addition to impairing the liver, kidneys, and immune system, Hg can cross the blood-brain protective barrier, causing damage to brain cells.
Regis: As long as CFL bulbs are intact, there is no Hg exposure. The actual amount of Hg in new CFLs is only 3–5 mg, the size of a ballpoint pen tip. Some environmentally friendly bulbs contain as little as 1 mg.
Barbara: What should I do if a CFL breaks? I know that Hg is not radioactive, but it is volatile.
Regis: Proper cleanup for Hg spills is always essential. The U.S. Environmental Protection Agency (EPA) recommends airing the room and using sticky tape to collect small pieces. Then, place this material in a sealable plastic bag and call 1-800-CLEAN-UP for the nearest disposal center.
Barbara: CFLs are very expensive, and they may further endanger our environment. How can I justify their purchase?
Regis: Although CFLs cost more than incandescent bulbs, they last 10 times longer, thus saving electricity and reducing the hidden environmental costs related to producing electricity by burning coal.
Mercury, a trace impurity in coal, is released into the atmosphere along with carbon dioxide—a greenhouse gas—during combustion. In fact, one of the largest sources of atmospheric Hg is coal-fired power plants. Even though there is Hg inside CFLs, we potentially reduce the Hg released into the environment.
According to the EPA, if every home converted one bulb to a CFL, we would save enough energy every year to light 3 million homes and prevent greenhouse gas emissions equivalent to those from 800,000 cars. What a great way to help reduce our dependence on fossil fuels!