Skip Navigation

Coronavirus (COVID-19) information for Dana-Farber patients & families Learn more

Public poorly informed about potentially harmful substances in e-cigarette secondhand vapor

  •  Andy Tan, PhD, MPH

    The plumes of vapor exhaled by e-cigarette users may look like pure mist and exude a fruity aroma, but a new study led by Dana-Farber Cancer Institute researchers suggests that most people are unaware that the vapor contains more than water and may include potentially harmful substances such as formaldehyde.

    Inaccurate knowledge about the contents of secondhand vapor is concerning according to the authors of the paper, published online today by Risk Analysis. Previous Research showed that people who see a low risk in breathing secondhand cigarette smoke are more likely to take up smoking themselves. Now, there’s concern that this pattern could repeat itself with e-cigarette use, particularly among young people.

    The vast majority of respondents – 58 to 75 percent – reported that they didn’t know whether it contained only water vapor or also carried tar and/or formaldehyde. Sizable minorities said, incorrectly, that secondhand vapor contains only water vapor (21 percent), that it contains tar (10 percent), or that it doesn’t contain formaldehyde (15 percent). Current cigarette smokers had less knowledge about the chemicals in secondhand vapor than non-smokers did.

    The study findings also have implications for policies on vaping in public venues such as restaurants, bars, and parks. Previous studies found that public awareness of the dangers of secondhand cigarette smoke often translates into support for smoke-free policies. Again, there’s good reason to believe the same will hold true for vaping restrictions.

    “The U.S. Food and Drug Administration [FDA] has recently exerted its regulatory authority to require e-cigarette manufacturers to test their products for harmful and potentially harmful constituents and report the results to the FDA,” said the paper’s lead author, Andy Tan, PhD, MPH, of Dana-Farber and the Harvard T.H. Chan School of Public Health. “Our findings underscore the need to make sure the new rules are implemented industry-wide to ensure the public is adequately informed about the potential hazards of these products.”

    In this study investigators surveyed 1,449 U.S. adults online, asking them whether e-cigarette vapor contains only water vapor, or whether it also contains tar and/or formaldehyde. They were also asked whether they considered breathing secondhand vapor to be harmful to health.

    Investigators also found that people with accurate knowledge of the chemical content of secondhand vapor were more likely to consider it to be harmful.

    The study provides an early indication of the need for public education on the potential hazards of a relatively new but rapidly expanding practice, the authors write. E-cigarettes were introduced in the United States in 2006 and as of last year, nearly 13 percent of U.S. adults had tried at least one and 8 percent of those who have tried one used them daily, according to data from the Centers for Disease Control and Prevention.

    While e-cigarette vapor contains fewer chemicals, at lower levels, than cigarette smoke (which has more than 7,000, at least 69 of which are known to cause cancer, according to the American Lung Association), it is far from being “only water vapor,” as past advertising and marketing campaigns have claimed, Tan remarks. Recent studies have shown that in addition to nicotine and formaldehyde, vapor contains an array of other substances such as heavy metals and particulate matter, albeit in small amounts.

    The senior author of the study is Cabral Bigman, PhD, of the University of Illinois at Urbana-Champaign. Co-authors are Susan Mello, PhD, of Northeastern University and Ashley Sanders-Jackson, PhD, of Michigan State University.

    The study was supported by the Annenberg School at the University of Pennsylvania and the University of Southern California, and in part by the National Heart, Lung, and Blood Institute (grant number T32HL007034) and the National Cancer Institute (grant number P20CA095856).

Posted on September 06, 2016

  • Andy Tan, PhD, MPH, MBA, MBBS
  • Risk & Prevention
  • Media Contacts

    If you are a journalist and have a question about this story, please call 617-632-4090 and ask to speak to a member of the media team, or email

    The Media Team cannot respond to patient inquiries. For more information, please see Contact Us.

  • New Patient Appointments

    For adults: 877-442-3324
    For children: 888-733-4662

    Make Appointment Online