Thursday, March 8, 2018

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 CompoundControlsE-Cig UsersDual Users

Ethylene Oxide1.30.51.0
Propylene Oxide152940
*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. 

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