How Dangerous Does Mercury Make CFLs?

Not so sure about the facts as stated: "Because CFLs are 75 percent more efficient than incandescents, producing the electricity needed to power an incandescent bulb causes four times the mercury pollution than does producing the power to run an equivalent CFL." Who came up witth the amount of mercury pollution in power plants? Only coal fired power plants, and only soft coal fired plants-then I could believe this. But because so much of our energy comes from other sourced power plants, I doubt the overall mercury pollution effect is 4 times. Maybe closer to equal. BUT I still believe it is a better route to go because one is actual pollution into the atmosphere. The other is a possible pollution.