E-Cigarettes May Expose Nonsmokers to Carcinogens

A preliminary study presented at the recent Society for Research on Nicotine and Tobacco (SRNT) annual meeting found that nicotine released from electronic cigarettes (e-cigarettes) leaves a residue on various indoor surfaces, potentially exposing nonsmokers to dangerous carcinogens.

“Our work suggests that thirdhand exposure is possible not just from tobacco cigarettes, but also e-cigarettes,” said senior author Maciej L. Goniewicz, PhD, PharmD, Assistant Professor of Oncology, Department of Health Behavior, Division of Cancer Prevention and Population Sciences, Roswell Park Cancer Institute, Buffalo, New York.
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He explained that thirdhand exposure occurs “when nicotine and other chemicals from secondhand smoke deposit on surfaces, such as walls, tables, floors, and even clothes, exposing people via touch, ingestion, and inhalation. Children and infants are especially vulnerable due to their increased exposure and sensitivity.”

“The potential danger of thirdhand exposure to tobacco smoke continues long after smoking has ceased, even for years,” he said. “Nicotine is incredibly difficult to remove. While this may be possible for walls, it may be impossible to do so for a carpet. Because e-cigarettes have just entered the market, there is little research on them, and even less on how they may contribute to thirdhand exposure.”

To assess the levels of nicotine deposits on surfaces released from e-cigarettes, researchers conducted four experiments with three brands of e-cigarettes that were filled with different nicotine concentrations.

The nicotine was vaporized with a syringe in an exposure chamber. Goniewicz and colleagues then obtained surface wipe samples to measure the level of nicotine left on five surfaces of the chamber (ie, windows, walls, floor, wood, and metal).  

Significant increases in nicotine residue were found on all of the surfaces in three of the four experiments. These levels varied according to the surface. The floor and windows, for example, had the highest amounts of nicotine.

“As the time span after vaporization increased, more nicotine settled,” said Goniewicz. “Surface textures and location might have affected nicotine concentrations.”

In addition, he noted that the various brands of e-cigarettes used in the study emitted vapor differently.

“Different product characteristics may have affected properties of the vapor,” he added. “Some e-cigarettes may have created a vapor with larger particles that are more likely to fall to the floor. Differences in e-liquid ingredients and manufacturing may have affected the ability of nicotine to stick to surfaces.”

Regarding the limitations of the study, Goniewicz explained that the conditions in this analysis are not the same as those in an actual home of an e-cigarette user.

“Future research should explore the risks of thirdhand exposure from e-cigarettes in the homes of e-cigarette users and in public places and worksites where e-cigarette smoking occurs,” he said.

He also explained that because surface wipe samples were taken shortly after vaporization of the e-liquid, other research is needed to examine whether more nicotine would stick to these surfaces over longer periods of time.

“Clinicians should be aware about this new source of exposure to nicotine,” Goniewicz cautioned. “Although at this moment it is hard to predict what the clinical significance of this source is, we need to monitor and investigate this new route of exposure.”

This study is one of two on e-cigarettes from Roswell Park Cancer Institute presented at the SRNT meeting. Another study, also involving Goniewicz, found a more than 20% difference in nicotine concentrations from the amounts indicated on the product labels in 1 of 4 e-cigarette products. Researchers also detected nicotine in some refill solutions that claimed to be nicotine-free.

The study on thirdhand exposure was supported by Roswell Park Cancer Institute, the National Cancer Institute (NCI), and an NCI Continuing Umbrella of Research Experiences (CURE) supplement.

-Meredith Edwards White

Reference

Lee L, Travers M, Goniewicz M. Assessment of thirdhand exposure to nicotine from electronic cigarettes. Poster POS1-6 presented at the Society for Research on Nicotine and Tobacco conference; 2014 Feb 5-8; Seattle, WA.

Reinhardt S, Goniewicz M. Consistency of labeled nicotine content in electronic cigarettes: regulatory challenges. Poster POS2-40 presented at the Society for Research on Nicotine and Tobacco conference; 2014 Feb 5-8; Seattle, WA.