Changes in Biomarkers of Exposure and Subjective Effects When Smokers Switch to Dual Use of Cigarettes and Either Snus or a Dissolvable Tobacco Product: A Summary of Three Clinical Studies

A series of ambulatory clinical studies were conducted to evaluate changes in biomarkers of tobacco exposure and subjective product ratings when adult smokers switched to dual use of cigarettes with Camel Strips (Strips), Camel Sticks (Sticks), or Camel (SNUS). In all studies, subjects smoked ad libitum for one week (baseline). In incremental stages over three subsequent weeks, subjects were instructed to reduce cigarettes per day (CPD) by at least 75% and include use of one type of smokeless tobacco product (STP). Product use data was recorded by subjects daily, questionnaires were administered and smoked cigarette filters and used snus pouches were collected weekly, and 24-hour urine samples were collected at baseline and the end of dual use for measurement of biomarkers of tobacco exposure. In total, 100 subjects were enrolled, and 88 completed the studies. At the end of dual use, mean CPD reductions of approximately 60% were reported in all studies. Median levels of biomarkers of 4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanone (NNK) and acrolein either did not statistically significantly change or showed statistically significant decreases in all studies. Serum and urinary nicotine biomarkers did not significantly change. Twentyfive additional biomarkers were measured only in the SNUS study. Of those, 18 biomarkers statistically significantly decreased 12.4-35.7%. No statistically significant increases in biomarker levels were observed in any of the studies. Decreases in some biomarkers confirmed that smoking reductions occurred but were less than the reported CPD reductions. Mouth-level exposure estimates suggest subjects did not significantly alter their puffing behavior to compensate for decreased CPD. Acceptability ratings of cigarettes decreased significantly during dual use, while ratings of Strips and SNUS increased, suggesting that the change in use behavior affected subjects’ perceptions of the products. Results from these studies suggest that smokers who switch to dual use with either dissolvable tobacco or snus will likely not increase tobacco constituent exposure and may reduce exposure to some tobacco toxicants, especially those associated with combustion.