The study found that, for the first time, the major carcinogens and cancer-causing agents in tobacco products, which researchers call tobacco-specific nitrosamines, were found in higher levels in U.S. cigarettes than in cigarettes from Australia, Canada and the United Kingdom.
"We know that cigarettes from around the world vary in their ingredients and the way they are produced," Dr. Jim Pirkle, deputy director for science at the CDC's National Center for Environmental Health, Division of Laboratory Sciences, said in a statement. "All of these cigarettes contain harmful levels of carcinogens, but these findings show that amounts of tobacco-specific nitrosamines differ from country to country, and U.S. brands are the highest in the study."
Researchers studied 126 daily smokers from the four countries. The CDC doesn't specify which U.S. brand was used, only identifying it as an "American blend" that represented popular brands.
The scientists observed the smokers over a 24-hour period, measuring the level of nitrosamines in the cigarette butts to determine how much entered the smokers' bodies through their mouths. The level of nitrosamines was also measured in the study subjects' urine.
The study's results were published in the June issue of Cancer Epidemiology Biomarkers and Prevention.