Systematic review of what the chemistry of contaminants in electronic cigarettes tells us about health risks

[Jake6731]

Published yesterday..
BMC Public Health | Abstract | Peering through the mist: systematic review of what the chemistry of contaminants in electronic cigarettes tells us about health risks

Another very interesting study by Dr. Burstyn:

Key conclusions:

• Even when compared to workplace standards for involuntary exposures, and using severalconservative (erring on the side of caution) assumptions, the exposures from using e-cigarettes fall well below the threshold for concern for compounds with known toxicity.That is, even ignoring the benefits of e-cigarette use and the fact that the exposure isactively chosen, and even comparing to the levels that are considered unacceptable topeople who are not benefiting from the exposure and do not want it, the exposures wouldnot generate concern or call for remedial action.
  
• Expressed concerns about nicotine only apply to vapers who do not wish to consume it; avoluntary (indeed, intentional) exposure is very different from a contaminant.
  
• There is no serious concern about the contaminants such as volatile organic compounds(formaldehyde, acrolein, etc.) in the liquid or produced by heating. While thesecontaminants are present, they have been detected at problematic levels only in a fewstudies that apparently were based on unrealistic levels of heating.
  
• The frequently stated concern about contamination of the liquid by a nontrivial quantity ofethylene glycol or diethylene glycol remains based on a single sample of an early-technology product (and even this did not rise to the level of health concern) and has notbeen replicated.
  
• tobacco-specific nitrosamines (TSNA) are present in trace quantities and pose no more(likely much less) threat to health than TSNAs from modern smokeless tobacco products,which cause no measurable risk for cancer.
  
• Contamination by metals is shown to be at similarly trivial levels that pose no health risk,and the alarmist claims about such contamination are based on unrealistic assumptionsabout the molecular form of these elements.
  
• The existing literature tends to overestimate the exposures and exaggerate theirimplications. This is partially due to rhetoric, but also results from technical features. Themost important is confusion of the concentration in aerosol, which on its own tells us littleabout risk to heath, with the relevant and much smaller total exposure to compounds in theaerosol averaged across all air inhaled in the course of a day. There is also clear bias inprevious reports in favor of isolated instances of highest level of chemical detected acrossmultiple studies, such that average exposure that can be calculated are higher than truevalue because they are “missing” all true zeros.
  
• Routine monitoring of liquid chemistry is easier and cheaper than assessment of aerosols.Combined with an understanding of how the chemistry of the liquid affects the chemistryof the aerosol and insights into behavior of vapers, this can serve as a useful tool to ensurethe safety of e-cigarettes.
  
• The only unintentional exposures (i.e., not the nicotine) that seem to rise to the level thatthey are worth further research are the carrier chemicals themselves, propylene glycol andglycerin. This exposure is not known to cause health problems, but the magnitude of theexposure is novel and thus is at the levels for concern based on the lack of reassuring data.