After governments have been phasing out incandescent light bulbs as energy hogs causing climate change in favor of expensive, mercury loaded, twisty bulbs which give off a harsh, flickering light which supposedly use less energy, some scientists have not so surprisingly discovered "they can release potentially harmful amounts of mercury if broken."

Also:

Levels of toxic vapour around smashed eco-bulbs were up to 20 times higher than the safe guideline limit for an indoor area, the study said.

It added that broken bulbs posed a potential health risk to pregnant women, babies and small children.

Also, the energy saving bulbs' subtly flickering harsh light can be dangerous:

Medical charities say they can trigger epileptic fits, migraines and skin rashes and have called for an ‘opt out' for vulnerable people.

Other than these dire health hazards, the bulbs are just fine according to environmentalists, who just don't seem to care--or know--that mercury is not good for the environment.