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 25^th to the 75^th 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 (75^th 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)
Metal	Maximum Vapor Level (ug/kg)	Daily FDA Maximum or CDC MRL* (ug)	Volume of Vaping Liquid Exceeding FDA Max or CDC MRL*
Aluminum	22.2	NA	--
Cadmium	0.13	2	15.4 LITERS
		0.136*	1.1 LITER*
Chromium	43.9	3	68 milliliters
Copper	51.0	30	588 milliliters
Iron	23.6	NA	--
Manganese	9.56	4.08*	427 milliliters*
Nickel	289	5	17.3 milliliters
Lead	37.1	5	135 milliliters
		30*	808 milliliters*
Antimony	1.93	20	10.4 LITERS
Tin	19.4	60	3.1 LITERS
Zinc	809	NA	--

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 75^th 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.

Antidote to NEJM Formaldehype Arrives at Last

In January 2015, R. Paul Jensen and colleagues created global headlines with a defective e-cigarette experiment (here).  They claimed in the New England Journal of Medicine that vapor contains “hidden” formaldehyde at far higher levels than cigarettes (here).  Their measurements required overheating or “dry-puffing” e-cigarette liquid, a process that produces such harsh (not hidden) oral sensations that the vapor is intolerable to normal consumers. 

As Churchill said, “A lie gets halfway around the world before the truth has a chance to get its pants on.”  The Jensen mischaracterization caused considerable damage, as it encouraged smokers to believe that vaping is more dangerous than smoking. 

Last week, the formaldehyde fallacy was laid bare.  Dr. Konstantinos Farsalinos and colleagues reproduced the Jensen experiment and found that “The high levels of formaldehyde emissions that were reported in [the Jensen] study were caused by unrealistic use conditions that create the unpleasant taste of dry puffs to e-cigarette users and are thus avoided.” Their work appears in Food and Chemical Toxicology (abstract here). 

Farsalinos’ group painstakingly reproduced the earlier experiment, using the same now-outdated vaping equipment that was prone to dry puffs.  First, they had experienced vapers identify at what settings the “burning” taste of a dry puff was detected: 4.2 volts, 8.0 watts.  They then used Jensen’s methods to measure formaldehyde at various voltage-power settings, seen in the chart (above) adapted from their publication.

Vapers detected dry puffs when the formaldehyde level was 100 micrograms (per 10 puffs).  Given that a microgram is one-millionth of a gram, Jensen’s formaldehyde level wasn’t hidden at all; at 380 micrograms, it was much higher than vapers could tolerate.  At lower, normal vaping power, formaldehyde was only 20 micrograms, or two-thirds that of cigarettes.

Farsalinos cautions the scientific community: “blindly testing e-cigarettes in the laboratory setting without evaluating realistic use is a serious omission that can result in misleading conclusions about the risk to consumers compared to smoking;” and such conclusions can wrongly imply “that there is little to be gained by switching to e-cigarettes.”

In response to the Jensen article in 2015, Clive Bates and Konstantinos Farsalinos published a letter in Addiction calling for its retraction (here); the demand was ignored.  The current publication is a much-needed antidote to Jensen’s seriously flawed and misleading findings.