Atlanta ? American-made cigarettes such as Marlboros contain up to twice as much of a cancer-causing chemical as foreign brands, federal health officials said Friday.

The Centers for Disease Control and Prevention compared levels of the carcinogen nitrosamine in Marlboros, chosen because of their wide availability, with local brands in 13 other countries. In 11 countries, local brands had much lower levels than Marlboro.

CDC officials said the higher nitrosamine levels in American-made cigarettes were a result of the way the tobacco was cured and blended.

“What this says to us is it is possible for the manufacturer to lower the levels of this carcinogen,” said David Ashley, who led the study, published Friday in the journal Nicotine and Tobacco Research.

The CDC also compared Marlboros, which are made by Philip Morris, with U.S. competitor Doral, manufactured by R.J. Reynolds. Both brands had similar nitrosamine levels.