Traditional 'incandescent bulbs' used for more than 120 years are being phased out by th European Union which is persuading people to use low-energy alternatives.
Although this is being done to meet climate change targets, energy-saving light bulbs are at the centre of a fresh health scare after researchers claimed that these bulbs could release potentially harmful amounts of mercury if broken, reports the Daily Mail.
They said that broken eco-bulbs posed a potential health risk to pregnant women, babies and small children.
The study, for Germany's Federal Environment Agency, said that the levels of toxic vapour around smashed eco-bulbs were up to 20 times higher than the safe guideline limit for an indoor area.
The scientists at the Fraunhofer Wilhelm Klauditz Institute tested a 'worst case' scenario using two CFLs, one containing 2 milligrams of mercury and the other 5 milligrams.
They found that the bulbs released around 7 micrograms (there are 1,000 micrograms in a milligram) per cubic metre of air. The official guideline limit is 0.35 micrograms per cubic metre.
During the tests, the researchers were alarmed to discover that some bulbs had no protective cover and broke when hot.
High levels of mercury were measured at floor level up to five hours after the bulbs failed.
"Children and expectant mothers should keep away from burst energy-saving lamps," said a spokesman for the agency.
"For children's rooms and other areas at higher risk of lamp breakage, we recommend the use of energy-saving lamps that are protected against breakage.' However, the UK Government insisted the CFL bulbs were safe - and that the risk from a one-off exposure was minimal," he added.
Meanwhile, the Health Protection Agency said a broken CFL is unlikely to cause health problems. However, it advised people to ventilate a room where a light has smashed and evacuate it for 15 minutes.
CFLs are not supposed to be put in the dustbin, whether broken or intact, but taken as hazardous waste to a recycling centre.
"The mercury contained in low-energy bulbs does not pose a health risk to anyone immediately exposed, should one be broken,' said a spokesman for the Department for Environment, Food and Rural Affairs.