Examining Sidestream Smoke Exposure with the Centers for Disease Control and Prevention

Centers for Disease Control and Prevention (CDC) and Battelle recently conducted a study to gain a better understanding of disease risk associated with the exposure of non-smokers to sidestream smoke, which is the smoke that emits from the end of a lit cigarette. In other studies, it has been found that sidestream smoke is two to five times more concentrated in some carcinogens than the mainstream smoke inhaled by a smoker.

The study focused on how biomarkers of cigarette smoke exposure are affected by cigarette configuration (menthol vs. non-menthol), race, and gender in an attempt to further examine the finding in the Surgeon General’s report on smokers, which indicated that the incidence and mortality rate for African American men was twice as high for smoking-related cancers (lung, oral, and esophageal) than for Caucasian men. This statistic is somewhat intriguing in that African American smokers often smoke substantially fewer cigarettes per day than Caucasian smokers and are generally three times more likely to smoke a menthol cigarette than Caucasian smokers.

Forty non-smokers, consisting equally of men and women, and African Americans and Caucasians, were recruited for the study. These subjects were exposed to a controlled level of sidestream smoke generated using a 30-port automated smoking machine and Battelle’s large environmental chamber. The machine smoked menthol or non-menthol cigarettes to produce sidestream smoke levels similar to those found in a smoky bar. Saliva, blood, and urine samples were collected from each subject before, during, and after exposure. During each four-hour exposure period, carbon monoxide, nicotine, particle distribution, air exchange rate, temperature, and relative humidity were measured in the chamber. CDC was responsible for analyzing the biological samples for specific tobacco-related metabolites.

Increases in serum, urine, and salivary cotinine concentrations with exposure were essentially the same for men and women, and for African Americans and Caucasians. Although salivary cotinine differences between pre- and post-exposure were consistently greater for subjects exposed to sidestream smoke from menthol compared with non-menthol cigarettes, this difference was not statistically significant. Two carcinogen markers of interest (4-aminobiphenyl and NNAL) also showed relatively small differences in response according to race, gender, or cigarette type.

The carbon monoxide and nicotine measurements demonstrated similar levels for menthol and non-menthol cigarettes. However, the particle distribution indicated that the menthol cigarettes used in this study produced significantly more smaller-diameter particles than the non-menthol cigarettes. This result is important from a disease-risk standpoint, as smaller particles (0.3 – 0.5 µm) are more likely to reach the alveolar region of the lung, and thus carcinogens attached to them may take a longer time to clear from the body.

For more information, contact Ms. Marielle Brinkman at (614) 424-5277, brinkmmc@battelle.org