Friday, March 2, 2018

Beyond the Headlines, E-Cigarette Vapor Has Only Trace Amounts of Metals

The American media have been obsessed with a new study (here) claiming that “e-cigarettes are a potential source of exposure to toxic metals (chromium, nickel, and lead), and to metals that are toxic when inhaled (manganese and zinc).”

The headlines misrepresent or overdramatize the facts:      

“E-Cig Vapors May Contain Brain-Damaging Toxic Metals, Says New Study” Tech Times

“E-Cigarette Vapor Filled With Dangerous Toxins Like Lead, Study Finds” Newsweek

“E-cigarettes leak toxic metals, study finds” Medical News Today

“Are E-Cigarettes Safe? Alarming Levels Of Metal Found In Its Heating Coils” International Business Times

The research, published in the journal Environmental Health Perspectives, was authored by faculty at Johns Hopkins University, Columbia University, and the Universities of Granada (Spain) and Graz (Austria). 

They reported the metals’ median levels and range (from the 25th to the 75th percentile) in 56 e-cigarette devices’ aerosols.  All values are in micrograms (ug, one-millionth of a gram) of metal per kilogram (kg, one thousand grams) of vape aerosol.  For reference, there are 454 grams in a pound. 

The following table shows how much liquid an e-cigarette user must vape per day to exceed either the FDA’s daily exposure limit for inhaled medicines (here), or the CDC’s minimal risk levels (MRLs) for workplace inhalation (here).  I used the upper level (75th percentile) of the range, so the results below are not underestimates. 

Maximum Levels of Metals in E-Cigarette Vapors, and Amount of Liquid Used Daily to Exceed FDA Maximum Levels for Inhaled Medicines And/Or CDC Minimal Risk Levels (MRLs)
MetalMaximum Vapor Level (ug/kg)Daily FDA Maximum or CDC MRL* (ug)Volume of Vaping Liquid Exceeding FDA Max or CDC MRL*
Cadmium0.13215.4 LITERS
0.136*1.1 LITER*
Chromium43.9368 milliliters
Copper51.030588 milliliters
Manganese9.564.08*427 milliliters*
Nickel289517.3 milliliters
Lead37.15135 milliliters
30*808 milliliters*
Antimony1.932010.4 LITERS
Tin19.4603.1 LITERS
NA, not available

One thing is crystal clear: an e-cig user could be exposed to excessive metal levels only by consuming high volumes of vape liquids.  For example, vapers would have to use 15.4 liters (nearly four gallons) of liquid per day to achieve exposure to 2 micrograms of cadmium. 

Nickel is an outlier because at a high 75th percentile value (289 ug/kg), the exposure limit is 17 milliliters (the typical vaper uses 10 milliliters or less daily).  However, the median value for nickel in all samples was much lower (6 ug/kg), meaning that users could consume 800 milliliters before reaching the recommended exposure limit.

The authors emphasize that some of these metals, notably cadmium, chromium, nickel and lead, are toxic.  However, they fail to mention that toxicity is proportional to dose and duration.  The metal doses delivered by e-cigarette liquids in this study are trivial.

Note: Thanks to Dr. Konstantinos Farsalinos, a researcher at the Onassis Cardiac Surgery Center,
the University of Patras and the National School of Public Health in Greece, for his expert assistance with this entry.

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