Study: Second-hand smoke from e-cigarettes contains toxic metals

Second-hand smoke from electronic cigarettes may be less harmful than their tobacco-laden cousins, but they still release toxins into the air, according to a new study.

For the study, published in the Journal of Environmental Science, Processes and Impacts, researchers at the University of Southern California analyzed second-hand smoke from e-cigarettes and found an overall 10-fold decrease in exposure to harmful particles compared to traditional cigarette smoke. However, they did find a significant increase in exposure to some harmful metals coming from e-cigarette smoke.

Second-hand smoke from e-cigarettes also yielded exposure to almost no polycyclic aromatic hydrocarbons — cancer-causing compounds known as organic carcinogens — that are released into the air as tobacco cigarettes burn. But despite having less harmful organic compounds and an overall decrease in toxic metal emissions, e-cigarette smoke did contain chromium and nickel at levels four times higher than tobacco cigarettes. Lead and zinc were also found in the smoke, but they occurred at levels lower than regular cigarettes.

"Our results demonstrate that overall electronic cigarettes seem to be less harmful than regular cigarettes, but their elevated content of toxic metals such as nickel and chromium do raise concerns," said study author Constantinos Sioutas, a professor at the USC Viterbi School of Engineering.

E-cigarettes have come under intense scrutiny recently with the World Health Organization calling for stiff regulations and bans on using the devices indoors.  The Centers for Disease Control and Prevention released a report Monday stating that e-cigarettes may be more tempting to non-smoking youths than conventional cigarettes, and once young people have tried e-cigarettes they are more inclined to give regular cigarettes a try.

"The metal particles likely come from the cartridge of the e-cigarette devices themselves – which opens up the possibility that better manufacturing standards for the devices could reduce the quantity of metals in the smoke," said Arian Saffari, a PhD student at USC Viterbi and lead author of the paper. "Studies of this kind are necessary for implementing effective regulatory measures. E-cigarettes are so new, there just isn't much research available on them yet."

The study authors compared the smoke from a common traditional cigarette brand with smoke from an Elips Serie C e-cigarette, one of the most popular European brands. They noted that the results could vary based on which type of cigarettes and e-cigarettes are tested.