At noon on a recent weekday, all three footbaths at the Nail Spa in Rockville were occupied. Three manicurists hunched over the toenails of their customers. Two more technicians shaped acrylic nails on the outstretched hands of other clients.

Manicurist Theresa Phan brushed mauve polish on one customer's toes, then slipped to a back room for a quick lunch while the polish dried. But her rice was barely in the microwave when her next appointment stepped through the front door.

"Sometimes it's nothing, and sometimes they keep walking in," said Phan, 32, who came to the United States from Vietnam as a refugee seven years ago.

Vietnamese Americans such as Phan and her co-workers at the Nail Spa are being drawn into this business by the thousands, lured by the stable work and steady income. In the Washington area, as many as 70 percent of the 11,000 salons offering nail services are staffed almost exclusively by Vietnamese immigrants, according to owners.

The inexpensive services have triggered an explosion in the industry, transforming it from a luxury for the rich to a staple of care for those seeking beauty from finger and toe. At an upscale Chevy Chase salon, a set of acrylic nails costs $70. At discount salons, the price is about $25. A manicure is $12, a polish change $7.

But behind the storefront image of this flourishing beauty business is a mix of problems stemming from rapid growth, inadequate oversight and language barriers.

Operations have sprung up to provide fraudulent licenses, according to documents and interviews. In Maryland, the attorney general's office has begun a criminal investigation into allegations of license-buying. Investigators are looking into whether licensing test answer sheets were switched for applicants who say they paid as much as $2,000 for a guarantee they would pass.

According to cosmetology board records and state officials, many manicurists -- now known as nail technicians -- work without a license, which is required by most states to protect public health. To save money, salons also often reuse dirty implements, state officials say.

Violators are seldom caught because state regulators are overwhelmed by the thousands of businesses they must monitor. As a result, customers can face health risks, industry experts and officials say.

"Nobody realizes such pampering can be a health hazard," said Shelley Sekula Rodriguez, a Texas dermatologist who spoke about the risks during a meeting with colleagues in Washington this year.

Such problems haven't slowed business or dulled the aspirations of manicurists such as Phan, who says that the salon where she works is strict about following regulations.

After a stint as a grocery-store cashier, the Silver Spring resident has spent the past five years as a nail technician, working up to 10 hours a day, six days a week. Her goal is to buy a house and run her own shop with her husband, who also is a nail technician. Eventually, she hopes to work less and spend more time with her two children. She has seen many friends and co-workers achieve that kind of success.

"It's my dream," she said.

The industry's transformation began about a decade ago when Vietnamese Americans started entering the nail business in large numbers. That coincided with a wave of immigration: the Vietnamese population in the Washington area surged 86 percent during the decade, rising to more than 45,000.

These immigrants, generally less educated than the Vietnamese who had arrived in the 1970s and '80s, found the nail jobs to be especially attractive because they pay relatively well and require minimal English and little formal training. Vietnamese Americans have been drawn to the industry for no singular reason other than it has become a successful business niche for them.

In Maryland, the number of licensed manicurists has more than tripled since 1990, mirroring a national trend, according to industry publications. Some of the growth has been fueled by Vietnamese Americans moving from California, where the market is saturated.

"The first license they get is the driver's license," said Steve Nguyen, an Annapolis shop owner who has worked in the nail business for 12 years. "The second is the manicurist license."

That career path has made it possible to build a middle-class life within one generation, often with several family members in the business. Gene Nguyen, no relation, enrolled in nail school at 15. Now the 35-year-old runs a successful nail school and salon in Falls Church and plans to open 10 more shops within two years.

"You don't see any other business with a higher return than nails," he said. People with acrylic nails need to have them redone every two weeks. "That's 26 times [a year] a client can come and visit you."

Nail technicians typically earn $400 to $500 a week, usually receiving 60 percent of each sale. Working on commission means they need to work long hours, often six or seven days a week.

Such a schedule is the key to success, Gene Nguyen tells his students at Nails For You Training Academy. At the back of his salon, they practice applying acrylic nails and study the Vietnamese translations of "capillaries," "sensitive" and "nail bed."

On a busy Wednesday, students include a 55-year-old liquor store owner from Maryland's Eastern Shore and Meresa Tran, 29, a nursing-care assistant from Silver Spring.

Nguyen is teaching Tran the basics of a safe manicure. In four days, Tran will quit her job as a nursing-care assistant. Barely five feet and about 100 pounds, she is tired of bathing, feeding and lifting nursing-home residents twice her size for $7 an hour.

"Well, if you really put your mind to it, do it the way I teach you -- you can make $1,000 a week," Nguyen tells her.

"Yeah?" she asks, her eyes widening.

"Yes, you can make $1,000 a week," Nguyen assures her. "Not including tips."

But breaking into the business can be difficult. The District and most states, including Maryland and Virginia, require applicants to have more than 100 training hours before they can take a written and practical exam. The District administers the written exam in English and in Spanish. But Maryland and Virginia give the test in English only, because technicians need to be able to read labels in English. Translators were banned in 1997 because of cheating.

For many who want to become technicians, limited English presents a major hurdle, and some have resorted to illegal shortcuts.

Nancy Nguyen, a Montgomery County salon owner who is not related to Steve or Gene, said she helped at least two manicurists purchase licenses. She said that one woman she helped brought back a receipt, "like the kind you would get from a yard sale," for the $2,000 fee she paid.

That woman and six others contacted by The Washington Post who allegedly purchased licenses declined to be interviewed or denied obtaining their licenses fraudulently. But five friends and co-workers of these technicians told The Post that they knew directly of the license-buying and had helped, such as by making phone calls or driving them to the test site.

Steve Nguyen, the Annapolis salon owner, said that three years ago he helped a friend obtain a license in Maryland after she had failed the exam for the fourth time. He drove her to a Silver Spring house, where she handed over a cash-filled envelope.

About two weeks later, Nguyen said, he drove his friend to the state board's test site, Aspen Beauty Academy in Laurel, where she took the written test. State cosmetology records show she passed Nov. 30, 1998. The woman, who works in a salon in Anne Arundel County, would not comment for fear of losing her license.

The Maryland attorney general is investigating allegations about the way the exams were administered, including the role of former test site administrator James W. Prince, according to a government source with knowledge of the probe. Authorities are looking into allegations that customers of Melanie Jean Prince, who ran a tutoring service for nail exams, had their answer sheets switched at the test site run by her husband, James Prince, said Steve Nguyen, who was told this during an interview with the attorney general's office.

A spokesman for the attorney general's office would neither confirm nor deny the investigation. But Billie Paige, president of Continental Testing Services Inc., a private company that administers the Maryland exams and that employed James Prince, said her company was informed of the investigation by the attorney general's office. The company said Prince resigned May 14 to take another job.

James Prince would not comment during two visits in April to the Laurel test site, where Washington area residents take their exams, and did not return several subsequent telephone calls left at his office and his home.

Until March, Melanie Prince operated Educational Services Unlimited, a tutoring service for aspiring manicurists located in a second-story office in a Langley Park shopping center. She would not discuss her business other than to say she operated a "tutorial service."

A company fact sheet in Vietnamese says the service's goal is to "help you pass the test from the state board." In boldface letters in English, it adds: "The result is guaranteed."

License-buying is not the only problem in the nail industry.

Unsanitary conditions and unlicensed technicians are pervasive, according to state cosmetology board records and interviews with technicians, salon owners and state officials. About 77 percent of the 208 violations in nail and beauty salons reviewed by the Maryland State Board of Cosmetologists over three months last year dealt with poor sanitation or shops and practitioners operating with no license or expired licenses. The remainder cite other infractions, such as improper use of cutting instruments.

The owner of LT Nail in Colonial Heights, Va., told a state investigator in 1997 that the salon did not clean instruments after each customer "unless the customer bleeds or the customer's hands are dirty," according to the investigator's report.

In April, the Centers for Disease Control and Prevention reported that at least 110 customers who received pedicures last summer at a nail salon in Watsonville, Calif., developed boils and skin ulcers from high levels of bacteria in the salon's footbaths.

Also, industry experts say a dangerous chemical is making a comeback. The chemical, methyl methacrylate, or MMA, has been linked to infections and nail deformities.

The Food and Drug Administration has labeled it harmful in nail products, but officials say salons often use it to form acrylic nails because it is less expensive than similar products. It is banned in Maryland, and the District plans to prohibit its use.

State cosmetology boards are responsible for overseeing the industry. But the boards lack the resources and clout to monitor salons and administer tough penalties. If someone is working without a proper license, for example, authorities may penalize only the salon owner, though that will change in Maryland on Oct. 1.

"I am extremely frustrated by the inability of the cosmetology board to efficiently and effectively oversee this industry," said Virginia Charles, a member of Maryland's seven-member appointed board.

In the Washington area, only Maryland requires salons to be inspected -- the goal is four times a year -- but because of budgetary restrictions, state board administrator Kathleen Harryman said some of the 21 part-time inspector slots go unfilled for long periods.

Virginia and the District send an inspector only in response to a written complaint. The District has 12 inspectors to cover more than 200 industries, such as tow truck operators and wholesale cigarette vendors. Virginia has 20 investigators to oversee 22 professions.

Among the complaints that have triggered investigations in Virginia was one filed in 1998 by Connie Zarba, a Virginia Beach travel agent who developed an infection after her foot was gouged with a razorlike instrument during a pedicure there. A state investigator found that the manicurist was unlicensed.

"I don't have a problem with people making a living, but the problem is the lack of enforcement," said Zarba, 60, a diabetic. "Isn't that the point of licensing people -- to make sure they're properly trained and safe for the public?"

Seeing the problems firsthand turned Annapolis salon owner Steve Nguyen into a whistleblower. He contacted state authorities in March after at least 20 people told him that they bought their licenses, he said. Some told Nguyen that they never took the required licensing test at all.

Nguyen, 36, said he blames states for not offering the test in Vietnamese. "In our community, the people want to have a job, and they want to have some chance [to pass] the test," he said.

Instead of being praised by the community for trying to stop what he saw as an abuse, he has been ostracized, he said. Vietnamese beauty suppliers treat him coolly. Two of his nail technicians quit. Friends no longer call.

"Now everybody is turning on me like I'm a monster," he said.

But Nguyen said he cannot afford to leave the industry, which remains hugely popular.

Key to that popularity are such customers as Vannie Harrell, who has had acrylic nails for eight years. Harrell, who helps run the family's Roanoke construction business, has her nails redone for about $13 every two weeks, sometimes every week. She loves that her nails don't chip, she said, and that her hands look attractive when she plays the piano at church. Even after a fungal infection turned her nails green -- an infection she believed was spread by a dirty electric drill -- Harrell did not change her beauty regimen. Instead, she switched salons.

"It's hard to break away from it," said Harrell, 46. "I could see how much more attractive my nails were, and I thought, 'Man, this is it.' "