With its slim white body and glowing amber tip, it can easily pass as a regular cigarette. It even emits what look like curlicues of white smoke.

The Ruyan V8, which produces a nicotine-infused mist absorbed directly into the lungs, is just one of a rapidly growing array of electronic cigarettes attracting attention in China, the U.S. and elsewhere _ and the scrutiny of world health officials.

Marketed as a healthier alternative to smoking and a potential way to kick the habit, the smokeless smokes have been distributed in swag bags at the British film awards and hawked at an international trade show.

Because no burning is involved, makers say there's no hazardous cocktail of cancer-causing chemicals and gases like those produced by a regular cigarette. There's no secondhand smoke, so they can be used in places where cigarettes are banned, the makers say.

Health authorities are questioning those claims.

The World Health Organization issued a statement in September warning there was no evidence to back up contentions that e-cigarettes are a safe substitute for smoking or a way to help smokers quit.

It also said companies should stop marketing them that way, especially since the product may undermine smoking prevention efforts because they look like the real thing and may lure nonsmokers, including children.

"There is not sufficient evidence that (they) are safe products for human consumption," Timothy O'Leary, a communications officer at the WHO's Tobacco Free Initiative in Geneva, said this week.

The laundry list of WHO's concerns includes the lack of conclusive studies and information about e-cigarette contents and their long-term health effects, he said.

Unlike other nicotine-replacement therapies such as patches for slow delivery through the skin and some inhalers and nasal sprays, e-cigarettes have not gone through rigorous testing, O'Leary said.

Nicotine is highly addictive and causes the release of the "feel good" chemical dopamine when it goes to the brain. It also increases heart rate and blood pressure and restricts blood to the heart muscle.

Ruyan _ which means "like smoking" _ introduced the world's first electronic cigarette in 2004. It has patented its ultrasonic atomizing technology, in which nicotine is dissolved in a cartridge containing propylene glycol, the liquid that is vaporized in smoke machines in nightclubs or theaters and is commonly used as a solvent in food.

When a person takes a drag on the battery-powered cigarette, the solution is pumped through the atomizer and comes out as an ultrafine spray that resembles smoke.

Hong Kong-based Ruyan contends the technology has been illegally copied by Chinese and foreign companies and is embroiled in several lawsuits. It's also battling questions about the safety of its products.

Most sales take place over the Internet, where hundreds of retailers tout their products. Their easy availability, O'Leary warns, "has elevated this to a pressing issue given its unknown safety and efficacy."

Prices range from about $60 to $240. Kits include battery chargers and cartridges that range in flavors (from fruit to menthol) and nicotine levels (from zero _ basically a flavored mist _ to 16 milligrams, higher than a regular cigarette.) The National Institutes of Health says regular cigarettes contain about 10 milligrams of nicotine.

On its Web site, Gamucci, a London-based manufacturer, features a woman provocatively displaying one of its e-cigs. "They look like, feel like and taste like traditional tobacco, yet they aren't," the blurb reads. "They are a truly healthier and satisfying alternative. Join the revolution today!"

Smoking Everywhere, a Florida-based company, proclaims it "a much better way to smoke!" while a clip on YouTube features an employee of the NJoy brand promoting its e-cigarettes at CES, the international consumer technology trade show.

Online sales make it even more difficult to regulate the industry, which still falls in a gray area in many countries.

In the U.S., the Food and Drug Administration has "detained and refused" several brands of electronic cigarettes because they were considered unapproved new drugs and could not be legally marketed in the country, said press officer Christopher Kelly.

He did not give more details, but said the determination of whether an e-cig is a drug is made on a case-by-case basis after the agency considers its intended use, labeling and advertising.

In Australia, the sale of electronic cigarettes containing nicotine is banned. In Britain, the products appear to be unregulated and are sold in pubs.

Smoking is tightly woven into the fabric of daily life in Ruyan's home turf of China, the world's largest tobacco market where about 2 trillion cigarettes are sold every year.

Tobacco sales, the biggest source of government revenue, brought in $61 billion in the first 11 months of last year, up 18 percent from 2007, the Communist Party's People's Daily newspaper said.

In a country where the cheapest brands of cigarettes cost about 20 cents a pack, the e-cig is far pricier. Ruyan's V8 costs $240 and includes batteries and 20 cartridges of nicotine solution, roughly the same number of puffs as 20 packs of tobacco cigarettes. The line has expanded to include cigars and pipes crafted from agate and rosewood.

Ruyan is suing a Beijing newspaper for questioning its safety and for claiming in 2006 that its products have more nicotine than regular cigarettes.

Miu Nam, Ruyan's executive director, blames the newspaper for a hit in sales and profits but declined to give details.

"We have to restore consumers' confidence, we have to clean up people's doubts," Miu said.

An operator at the Beijing Times refused to transfer calls seeking comment Friday to managers at the newspaper. A reporter said she had heard of the case but would not give any details.

Some international experts back Ruyan's claims its product is safe.

David Sweanor, an adjunct law professor at Ottawa University and former legal counsel of the Non Smokers Rights Association in Canada, said e-cigs have the potential to save lives.

With smoking, "it's the delivery system that's killing people," Sweanor said. "Anytime you suck smoke into your lungs you're going to do yourself a great deal of damage. Nicotine has some slight risks but they are minor compared to the risk of smoke in cigarettes."

Dr. Murray Laugesen, a New Zealand physician involved in tobacco control for 25 years who was commissioned by Ruyan to test its e-cigs, said he found "very little wrong" with them.

"It looks more like a cigarette and feels more like a cigarette than any other device so far and yet it does not cause the harm," he said. "It's the best substitute so far invented for tobacco cigarettes."

In the U.S, both Philip Morris USA and RJ Reynolds have introduced cigarettes that did not burn tobacco, but the technologies were very different from the e-cigarette. Neither has been successful.

In 2006, Philip Morris USA, test-marketed the Accord, which used a heating unit activated by puffing. RJ Reynolds introduced its cigarette, the Premier, in 1987 and still sells the Eclipse, which heats the tobacco rather than burning it. Sales are "not great," said spokesman David Howard.

Li Honglei, a fast-talking 28-year-old public relations manager in Beijing, has been smoking since he was in his teens and desperately wants to quit. He thinks he may have found his answer in Ruyan.

"I was intrigued by this new technology," said the pudgy, bespectacled Li as he surveyed products displayed in glass cases at Ruyan's brightly-lit shop in the capital. "I heard acupuncture is effective as well, but this method sounds more painless."

Associated Press writers Chi-Chi Zhang in Beijing, Vinnee Tong and Carley Petesch in New York and AP researcher Yu Bing in Beijing contributed to this report.

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