Beyond the Headlines: Trace Toxins, Present in All Teens, Improperly Blamed on E-Cigarettes

The University of California San Francisco publicized a study on March 5, asserting that “Adolescents who smoke e-cigarettes are exposed to significant levels of potentially cancer-causing chemicals.” (here)  The study’s lead author, Mark Rubinstein, M.D., said, “Teenagers need to be warned that the vapor produced by e-cigarettes…actually contains some of the same toxic chemicals found in smoke from traditional cigarettes.”

This led to messaging that vaping is just as dangerous as smoking -- “Teens Using E-Cigarette Have the Same Toxic Chemicals Found in Smokers” (here), “E-Cigarette Users Ingest High Levels of Cancer-Causing Chemicals” (here).

In fact, the research, published in Pediatrics, analyzed urine, not vapor.  The study reports the presence of minute amounts of volatile organic compounds (VOCs) in the urine of teens who didn’t smoke or vape (i.e., controls), e-cigarette users, and dual users of e-cigarettes and cigarettes.

Here are the study results:

Median VOC Levels (ng/mg*) in the Urine of Controls, E-Cig Users and Dual Users
Parent Compound	Controls	E-Cig Users	Dual Users
Benzene	0	0	0.2
Butadiene	0	0	0
Ethylene Oxide	1.3	0.5	1.0
Acrylonitrile	0	1.3	59
Acrolein	193	254	440
Propylene Oxide	15	29	40
Acrylamide	35	67	236
Crotonaldehyde	100	149	185

*ng/mg = parts per MILLION (creatinine)

Significantly, there were no cigarette smokers in the study.  Existing research tells us that their VOC levels would have been far higher, undercutting the UCSF anti-e-cigarette narrative.

Note that there are no alarming elevations in benzene or butadiene, and levels of ethylene oxide were actually lower among users than controls.  This data indicates that teens virtually no exposure to these chemicals.

While levels of other agents are higher in e-cigarette users and especially in dual users, levels in controls are not zero. 

The authors are on shaky ground in their attribution of higher toxin levels among e-cigarette users to the vapor.  A previous study (co-authored by one of the current authors, here) that they cite failed to find any acrolein and crotonaldehyde in vapor from 12 e-cigarettes.  A Centers for Disease Control and Prevention study (here) found that nonsmokers’ urine had up to 245 ng/g of acrolein and up to 158 ng/g of propylene oxide (smokers had far higher levels of both).  Thus, toxin levels seen in e-cigarette users in the new UCSF report are not necessarily due to vapor.

The UCSF research ignores a possible alternative source of these contaminants: recent marijuana smoking, as shown in a CDC study that identified elevated VOC levels among tokers (here).  As I recently noted (here), marijuana use is more prevalent among teens than vaping or cigarette smoking; data from one federal survey shows that about 40% of teen vapers are current marijuana users.  These findings increase the odds that toking impacted results in the new study.

The UCSF research was supported by four grants totaling some $32 million from the National Institutes of Health to authors Rubenstein, Neal Benowitz and Stanton Glantz. 

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.

Federal Officials, Please Pay Attention to Federal Surveys: E-Cigarettes Are Not Gateway Products

I noted in 2013 that the CDC director’s claim – that “many kids are starting out with e-cigarettes and then going on to smoke conventional cigarettes” – was pure gateway speculation (here).  Youth surveys had just started collecting information that teens were using e-cigarettes, but there was zero evidence that they were “going on to smoke.”

In January I presented data from the CDC’s National Youth Tobacco Survey showing that e-cigarette experimentation since 2011 did not produce an epidemic of teen smoking (here).  The 2017 Monitoring the Future survey, illustrated in the chart at left, provides further evidence of a steady decline in cigarette smoking among high school seniors.  In 2017, the smoking rate in MTF dropped below 10% for the first time in history.  At 9.7%, the rate is almost half that of 2011 (18.7%), while the vaping rate remained at 16-17%.  Meanwhile, high school seniors used alcohol and marijuana at far higher rates than cigarettes (33% and 23% respectively).  Nineteen percent of seniors reported being drunk in the past month.

MTF vaping data in 2014-2016 didn’t specify the liquids used; in 2017 MTF collected information on non-specific vaping and vaping nicotine and marijuana in the past month.  Nonspecific vaping, illustrated by the green line in the chart, was around 16%, nicotine vaping was 11%, and marijuana vaping was 4.9% in the past month.

Federal officials are still obsessed with the vape-to-smoke gateway, despite virtually no evidence.  FDA Commissioner Scott Gottlieb recently tweeted a warning: “The [e-cigarette] industry isn’t sustainable if it leads to a whole generation of youth initiation on tobacco.” (here) 

I tweeted a reply urging Dr. Gottlieb to look at his agency’s data from the “…PATH survey of 9,909 never-smoking teens. One year later, 219 (2.2%) had smoked in past 30 days. All awful, but 175 (80%) had no prior tobacco product use; only 11 had used e-cigs. FDA data shows vaping not major gateway to teen smoking [here].” (emphasis added)

Federal officials should stop claiming that vaping is a gateway to smoking, because evidence is absent in all federal surveys.