CHICAGO (Reuters) - Tobacco companies manipulate the amount of menthol in cigarettes to make those first few puffs more palatable to young smokers, U.S. researchers said on Wednesday in a finding that could fuel support for more tobacco regulation.

Smokers take a cigarette break outside a government office building in Boston, Massachusetts May 5, 2008. REUTERS/Brian Snyder

“Menthol stimulates the cooling receptors in the lung and oral pharynx,” said Dr. Gregory Connolly of the Harvard School of Public Health. “It makes smoking easier.”

The study, published in the American Journal of Public Health, comes as the U.S. Congress considers legislation that would give the Food and Drug Administration broad authority to regulate tobacco.

Representatives of tobacco companies R.J. Reynolds, Philip Morris and Lorillard disputed the findings.

“It would appear this report is simply an effort to push support for federal regulation of the tobacco industry, not a scientific review of the menthol category,” said David Howard, a spokesman for R.J. Reynolds, a unit of Reynolds American Inc and maker of Camel and Kool cigarettes.

Lorillard Inc spokesman Michael Robinson said in a statement: “The American public should view this report for what it is, a politically motivated lobbying tool.”

Smoking is the biggest cause of preventable death in the United States, killing more than 400,000 people each year.

Menthol cigarette brands have been rising in popularity with adolescents and the highest use has been among younger, newer smokers. A 2006 national survey found that 44 percent of smokers aged 12 to 17 reported using menthol cigarettes, as did 36 percent of smokers aged 18 to 24.

Connolly and colleagues studied internal company research on menthol use released as part of a large tobacco settlement. They also conducted independent laboratory tests and reviewed population studies on smoking trends.

According to the study, in 1987 R.J. Reynolds identified low menthol varieties as a new strategy to recruit new, young smokers.

“First-time smoker reaction is generally negative,” it said in a company document. “Initial negatives can be alleviated with a low level of menthol.”

STARTING OUT MILD

Big tobacco makers in the United States agreed in 1998 to pay $206 billion to 46 states to help pay the costs of treating ailing smokers under a 25-year master settlement. The deal, which included restrictions on the advertising and marketing of tobacco, ended a long legal battle with the states.

Connolly said tobacco companies use mild menthol cigarettes to target younger smokers and stronger menthol flavors for established smokers.

“Menthol helps the nicotine go down,” Connolly said in a telephone interview but he added that too much menthol is hard for new smokers to tolerate.

Among the brands tested, the researchers found those with the greatest market growth among young adults -- Lorillard’s Newport brand and Philip Morris USA’s Marlboro Milds -- had the lowest menthol levels.

He said it was clear to him that tobacco companies “are using an ingredient here to make nicotine addiction easier.”

David Sylvia, a spokesman for Altria Group Inc’s Philip Morris unit, disputed that the company manipulates menthol levels to gain market share among adolescents.

“There is very little direct relevant data that shows menthol affects initiation,” Sylvia said, adding the products “were not designed for nor marketed to underage smokers.”

He said Philip Morris supports FDA regulation of tobacco.

Lorillard, which opposes the legislation, also rejected the idea that the company targets youth smokers.

“Lorillard does not engineer any of its cigarettes to promote smoking initiation or nicotine addiction,” Robinson said.

According to the American Lung Association, each day 4,000 children under 18 smoke their first cigarette and almost 1,100 of them will become regular smokers.

Connolly said the findings underscore the need for tobacco regulation by the FDA.

The bill before the House of Representatives prohibits fruit- and candy-flavored cigarettes but exempts menthol from an immediate ban. But Connolly said the bill would grant the FDA the power to regulate menthol levels.

The lack of a specific ban on menthol has led the National African American Tobacco Prevention Network to withdraw its support for the bill, claiming it is incomplete and discriminates against blacks.

More than 70 percent of black smokers in the United States use menthol cigarettes, compared with about 30 percent of white smokers, the researchers said.

The Campaign for Tobacco-Free Kids said in a statement the study shows how a lack of tobacco regulation allows companies to manipulate their products in harmful ways.