BOSTON -- Energy-saving, spiral fluorescent bulbs that may help in the battle against global warming could pose a health risk to babies, small children and pregnant women, according to two new studies.

How Safe Are Energy-Saving Bulbs?

The Vermont-based Mercury Policy Project study showed the bulbs pose a threat of mercury poisoning if they break, prompting the federal Environmental Protection Agency and both Massachusetts and Vermont to revise recommendations for where homeowners should use the bulbs.

"There is a very tiny, tiny amount of mercury. It's one one-hundredth of what we used to know -- the mercury that used to exist in thermometers, for example," said Department of Environmental Protection Commissioner Laurie Burt.

The lights use about 1 percent of the mercury found in old thermometers, or 1 to 30 milligrams, but some amounts can be vaporized into the air if the lights break, posing a health risk. All fluorescent lights use mercury to produce light. Many states require that the energy-saving lights be recycled or disposed of as hazardous waste. Massachusetts is expected to ban disposal of the lights in the trash this spring.

Consumers were cautioned to avoid using the energy-saving bulbs on tables or in other places where they can be easily broken. Even so, the reports said, the bulbs, which use 75 percent less energy and last 10 times longer than incandescent bulbs, are still the best way for homeowners to try to save on electricity, adding that the benefits of using them outweigh the risks.

"The bulb lasts 10 times as long. It uses a fraction of the energy," said Gary Katz, of Harvey's Hardware Store.

Sales of the fluorescent bulbs have leaped in the U.S. and a new law requiring all bulbs to be more energy efficient will go into effect in 2012. The U.S. Energy Department said millions in energy costs could be saved if more Americans used the energy-saving bulbs.