All CFLs contain mercury, typically about 4 mg. Some manufacturers have reduced the amount to as little as 1 mg in some types of CFLs, and more manufacturers are following suit. Today, very few household products contain any mercury. Before the 1980s you could find mercury in paint, pesticides, dental fillings and fever thermometers. Is 4 mg a \"small\" amount? Relatively speaking, yes. Four mg of mercury easily fits on the tip of a ballpoint pen. A glass thermometer contains 100 to 600 times as much mercury as today’s typical CFL. (While glass thermometers are no longer used, it’s a useful comparison). Despite the small amount in a CFL, that doesn’t discount the fact that mercury is harmful. So, does the amount of mercury getting into the environment through increased CFL use offset the amount of mercury and other pollutants that get into the environment through coal-fired generation? Bottom line: The use of CFLs emits far fewer mercury emissions than the use of incandescent bulbs — even when accounting for the rise of renewable-energy generated electricity.