MECHANICSBURG, Pa. — It’s a message being drummed into the heads of homeowners everywhere: Swap out those incandescent lights with longer-lasting compact fluorescent bulbs and cut your electric use.

Governments, utilities, environmentalists and, of course, retailers everywhere are spreading the word.

Few, however, are volunteering to collect the mercury-laced bulbs for recycling — despite what public officials and others say is a potential health hazard if the hundreds of millions of them being sold are tossed in the trash and end up in landfills and incinerators.

For now, much of the nation has no real recycling network for CFLs, despite the ubiquitous PR campaigns, rebates and giveaways encouraging people to adopt the swirly darlings of the energy-conscious movement. Recyclers and others guess that only a small fraction of CFLs sold in the United States are recycled, while the rest are put out with household trash or otherwise discarded.

“In most parts of the country, it requires getting in your car and burning up your gas and going out of your way, a long ways, and people are unlikely to do this,” said Paul Abernathy, the executive director of the Association of Lighting and Mercury Recyclers in Calistoga, Calif.

Sales of the bulbs have skyrocketed this decade — doubling last year to about 380 million after registering just 17,000 in 2000, according to the U.S. Environmental Protection Agency.

Recycling efforts, though, are spotty at best.

Some communities are arranging special CFL drop-off events while some city or county hazardous waste collection facilities accept them.

Swedish retailer IKEA collects the bulbs at its 34 U.S. stores and manufacturer Osram Sylvania offers a mail-in program. A few governments have targeted retailers.

Compact fluorescent bulbs each contain roughly 5 milligrams of mercury, which health professionals say is tiny in relation to the amount in a glass thermometer. Using that estimate, almost 2 tons of mercury were in the 380 million sold last year. By comparison, about 50 tons of mercury are spewed into the air each year by the nation’s coal-fired power plants.

The longer fluorescent tubes, in use since World War II, contain slightly more mercury per lamp, but recyclers typically collect them in bulk from the biggest users, businesses and factories, which are required by federal law to dispose of them properly.

Even if recycling efforts have been meager, environmentalists and government officials say it is important to balance the positives of CFLs against any negatives.

For instance, CFLs can curtail the need for energy and thereby cut pollution from power plants. According to the Union of Concerned Scientists, a coal-fired power plant will emit about four times more mercury to keep an incandescent bulb glowing, compared with a CFL of the same light output.

“People should care about mercury and if they do, they should be working to save energy wherever they can and CFLs are a great answer to that,” said John Rogers, a senior energy analyst for the Cambridge, Mass.-based group.

To recycle his spent CFLs, Rogers bags them, stores them in the basement and drops them off when his town, North Reading, Mass., holds a recycling event.

The bulbs do not release mercury if they are used properly and recycled.