A review of some 9,000 observations across a number of peer-reviewed and “grey” literature. The review concludes that continued surveillance of users’ health and research into means of keeping adverse effects to a minimum should be pursued. However, it also claims there is no evidence that vaping exposes users to contaminants that would warrant health concerns. As exposures for bystanders are orders of magnitude less, there’s no apparent threat to secondhand vapers.
The review was conducted by Igor Burstyn with Drexel University’s School of Public Health in Philadelphia. Burstyn gathered observations from official peer-reviewed studies and what’s often called “grey literature.” Grey literature is informally publish material but often still supportable — this can include technical reports, papers from committee, and white sheets to name a few. Burstyn compared worst case assumptions based on studies of electronic cigarettes to normal workplace exposure standards and threshold limit values. What he found was that electronic cigarettes fell well below these limits.
You can read the review in full here.
To clarify, threshold limit standards (TLSs) are set levels at which daily exposure to a particular chemical is deemed to have no long term adverse effects. As e-cigs fall below these levels, it is likely that long term use of electronic cigarettes has no long term side effects. And again, as the levels of exposure are magnitudes lower for bystanders, there appears to be no threat from secondhand vaping.
The final conclusion pretty mush says it all:
“By the standards of occupational hygiene, current data do not indicate that exposures to vapers from contaminants in electronic cigarettes warrant a concern. There are no known toxicological synergies among compounds in the aerosol, and mixture of the contaminants does not pose a risk to health.”
Burstyn digs in a bit more with his key conclusions section revealing that tobacco-specific nitrosamines are present in trace quantities and pose no measurable risk for cancer. Similarly, presence of metal particulates and volatile organic compounds occur at trivial levels even for the users themselves. As well, concerns about contamination by unsafe levels of ethylene glycol or diethylene glycol are based on a single sample of an early-stage product and has yet to be replicated.
All in all, there’s been quite a lot of research into electronic cigarettes and it all bodes well for the products.