WASHINGTON -- The Environmental Protection Agency, more accustomed to going after large-scale polluters like smoke-belching factories, is cracking down on neighborhood mom-and-pop dry cleaners, forcing them to switch to greener cleaning agents instead of relying on a powerful stain remover linked to various health risks, including cancer.

Last month the EPA announced that many dry cleaners in urban areas must phase out the use of perchloroethylene , a heavy-duty solvent that removes dirt and grease from suits and jackets and sometimes leaves the familiar chemical smell on newly dry-cleaned clothes.

The agency cited studies showing that exposure to the chemical can cause headaches to neurological damage and increases the risk of cancer if it seeps into the air or water.

The crackdown gives the 28,000 dry cleaners across the country, including about 600 in Massachusetts, until 2020 to switch to greener technology if their stores share a building with apartments. But many of the dry cleaners, which tend to be locally-owned small businesses, say the transition is one they can't afford.

The cleaners, who lobbied unsuccessfully against the EPA ruling, say there are no good substitutes for ``perc," as it's known in the industry. The cost of complying with the new regulations, including spending tens of thousands of dollars for new equipment, could financially cripple some small businesses, they say.

``A lot of [dry cleaners] are very worried that they're not going to be able to adapt to these changes and survive," said Peter Blake, executive vice president of the Northeast Fabricare Association, which represents 8,000 dry cleaners in the Northeast. Buying new ecologically friendly equipment, Blake said, can cost as much as $80,000, an overwhelming burden for some family-owned cleaners.

``Everyone thinks they're big cash cows," he said. ``They're a Main Street business, and they are struggling."

Soon Young, the owner of Bijan Cleaners in Boston, said he was relieved that he would have 14 years to comply with the EPA's decision, but expressed concern that a new solvent wouldn't be powerful enough to satisfy his customers.

``The problem I can see is that the solvent replacing perc is not as good ," said Young, who immigrated to the United States in 1990 and has owned the store since 1995. ``Without the regulation, I would continue using perc, because I got used to it and its cleaning power is much better. I've been exposed much more often than regular people, but so far I don't have any health problems."

But environmental groups say the new rules are long overdue. Research linking dry cleaners to elevated perchloroethylene levels in humans emerged 15 years ago after several studies of apartment residents in New York City.

``Historically, dry cleaners have contributed quite a bit of pollution," said Liz Harriman, the deputy director of the Toxic Use Reduction Institute at the University of Massachusetts at Lowell.

The new EPA rules target cleaners that use older equipment or operate in a residential building. Blake said the impact on cleaners in the Commonwealth was likely to be ``severe" because of the size of Boston's urban areas, where dry cleaners tend to be located in residential buildings.

Judith Schreiber, one of the authors of a 1993 study that showed unhealthy perc levels in the bodily fluids of people who live close to dry cleaners, said the risks from dry cleaners were in some cases worse than from more obvious sources of pollution, like motor vehicles or factories.

Exposure to dangerous chemicals from cleaning shops ``are orders of magnitude higher than we see at Superfund sites, where we spend millions of dollars" to remove the hazard, said Schreiber, who is now a top scientist for New York's attorney general, Eliot Spitzer.

Schreiber praised the EPA rules, but criticized the agency for giving dry cleaners so long to change their ways.

``I think that is really a wrong-headed public health decision," she said. ``It's going to expose a whole generation of people to this chemical."

The dry-cleaning industry has developed several alternatives to perc, but they cost more and are labor-intensive, some dry cleaners said. They typically aren't as effective.

For example, cleaners have reported that a hydrocarbon solvent that has become one of the most popular alternatives to perc takes the sheen off silk gowns.

Dry cleaner Carl Levine, owner of Ross Cleaners in Brookline, said he has used perc for 40 years, and ``I have no horns growing out of my head." Ross Cleaners won't fall under the EPA ban because it's in a free-standing building. Levine said he spent $60,000 on a new perc cleaner and did not seriously consider the alternatives.

``I've seen them in action, and maybe you can drink the stuff and maybe it's 100 percent safe, but it's not effective as far as dry cleaning goes," he said.

Cleaners have voluntarily reduced their use of perc in recent years. The average amount of perc used in dry cleaners in the Bay State has declined from 181 gallons in 1997 to 107 gallons in 2005, according to Joe Ferson, a spokesman for the Massachusetts Department of Environmental Protection.

Still, specialists say some emissions are inevitable from even the most conscientious dry cleaners. Paul Reilly, an environmental analyst at the Massachusetts Department of Environmental Protection, said consumers should be wary if they notice a strong, sickly sweet odor, which indicates the chemical is in the air. ``When they walk into the store they shouldn't be able to get a smell of perc," he said.

For many years, Schreiber said, regulators were hesitant to move against dry cleaners, instead focusing on big corporate polluters.

That has changed as regulators found that pollution from dry cleaners, nail salons , and gas stations accounts for an increasingly large share of toxic pollution entering the atmosphere.

``The government is doing much better about regulating the very large factories, and now it's time to look at the more nuanced sources of pollution in our neighborhoods," said Leise Jones, a spokeswoman for Clean Water Action in Massachusetts.