Highly efficient fluorescent light bulbs are widely touted as environmentally friendly, but they have created a recycling headache for the Environmental Protection Agency and local governments. More often than not, their toxic ingredients simply end up in landfills, where the chemicals can leach into soil and water and poison fish and other wildlife. The bulbs contain mercury and should not be tossed in the trash as are regular light bulbs. "They're very efficient, but once they're used up, they become a ticking toxic time bomb," said Leonard Robinson, chief deputy director of the California Department of Toxic Substances Control. "They...