Cancer Risk Greater From e-Cigs Than Regular Cigarettes?

Pam Harrison

January 23, 2015

Researchers have found excessive levels of formaldehyde, an established carcinogen, in the vapor produced by e-cigarettes when the devices are used at high voltage. The cancer risk from this unexpected finding is much greater than from conventional cigarettes.

This finding was reported in a research letter published online January 22 in the New England Journal of Medicine.

But detractors — and there are a number — are calling the study "irresponsible" because the conditions under which these researchers analyzed e-cigarette aerosol in no way resemble the way the so-called "vapers" actually use e-cigarettes.

The researchers disagree. "We went out and obtained the device from a vaping store and we used it under standard settings. We did not modify it in any way," said lead author David Peyton, PhD, professor of chemistry at Portland State University in Oregon, when asked by Medscape Medical News about this purported design "flaw".

"It's not like we just pushed the button and generated as much vapor as possible; we generated the vaping puffs under what are considered standard puff conditions — 2-second puffs," he explained.

Although no formaldehyde-releasing agents were detected when the system was used at the low-voltage setting (3.3 V), at the high-voltage setting (5.0 V), a mean of 380 µg of formaldehyde per sample of 10 puffs was detected.

"Extrapolating from the results at high voltage, an e-cigarette user vaping at a rate of 3.0 mL per day would inhale 14.4 mg of formaldehyde per day in formaldehyde-releasing agents," Dr Peyton and colleagues write.

An estimated 150.0 µg of formaldehyde is delivered from a single conventional cigarette, which amounts to 3.0 mg from every pack of 20 cigarettes, they add.

The researchers estimate that the incremental lifetime risk for cancer associated with long-term conventional cigarette smoking at one pack a day for a person with a body weight of 70 kg (155 lb) is 9 × 10–4.

Assuming that formaldehyde-releasing agents carry the same risk per unit of formaldehyde inhaled as gaseous formaldehyde, "then long-term vaping is associated with an incremental lifetime risk for cancer of 4.2 × 10–3," the researchers report.

This is anywhere from five to 15 times as high as the risk associated with long-term smoking, depending on the method of calculation, they explain.

Furthermore, formaldehyde-releasing agents might actually be deposited more efficiently in the respiratory tract than gaseous formaldehyde, so they could carry an even higher risk for cancer, the researchers add.

The liquids used in e-cigarettes typically consist of propylene glycol, glycerol (or both), plus nicotine and flavorant chemicals.

Formaldehyde is a known degradation product of propylene glycol.

In many of the aerosol samples analyzed from the vaped e-cigarettes, more than 2% of the total solvent molecules were converted to formaldehyde-releasing agents, "reaching concentrations higher than concentrations of nicotine," the researchers report.

The same result was found when highly purified solvent mixtures containing no flavorant or nicotine were used, Dr Peyton told Medscape Medical News.

"It's not the result of the flavorant and it's not the result of the nicotine," he said. The formaldehyde is related to "the basic design of the e-cigarette."

Research Is "Absolutely Alarmist"

Gregory Conley, president of the American Vaping Association, counters that the research is "absolutely alarmist."

"When the vapor product device was tested at 3.3 volts, zero formaldehyde was detected," he pointed out to Medscape Medical News.

It was only when researchers increased the voltage to 5.0 — which is equivalent to about 12 watts — that formaldehyde was detected in the aerosol.

"That is extreme overheating territory," Conley explained.

"The peak amount of formaldehyde they found was 9 times the odor threshold for formaldehyde," he added.

If that amount was inhaled into the lungs, it would create a burning acrid taste in the mouth and a highly uncomfortable sensation in the lungs because the vapor would be exceedingly hot.

"As a vaper of 4 years, I can tell you that you get once what is called a 'dry puff,' you have zero interest in ever having one again," Conley said. A dry-puff is created when a vaper takes in a very long puff, which can occur in low- and high-voltage conditions.

Further, Conley noted, the study was done with a machine, and the results were extrapolated out 20 years, assuming that human vapers would be vaping just like these machines did in the experiment.

"If people are using high watts or high voltage, they take short puffs; they do not overheat their device," Conley asserted.

"These authors, very irresponsibly, did not even bother to consult a published study protocol about how you have to bring in human vapers to test what you are doing to make sure that the vapor being produced is actually something that a real-life vaper would use," he said.

Conley said he is concerned that the media hype surrounding this research will send the wrong message to consumers.

"If you pump rats full of sugar, the worst thing that's going to happen is that someone might decide to cut back on sugar," he said.

"But with a vapor-product study, the headlines have sent tens of thousands of smokers the suggestion that they shouldn't bother to quit — that e-cigarettes can be just as dangerous as regular cigarettes, so you might as well smoke," he added.

These concerns are echoed by Michael Siegel, MD, from the Boston University School of Public Health.

In a recent blog post, Dr Siegel criticizes the conditions under which the researchers analyzed the e-cigarette aerosol for formaldehyde content.

"The wattage being used was so high that the vaporizer was overheated," he writes. "This would create a horrible taste which a vaper could not tolerate" — the dry-puff phenomenon.

"What this study demonstrates is that if you overheat a vaping system, it will produce high levels of formaldehyde," Dr Siegel explains. "But extrapolating from this study to a lifetime of vaping is meaningless."

However, both Dr Peyton and Dr Siegel agree that the study did demonstrate that it is feasible to produce a vaping system that does not deliver any amount of formaldehyde, as it did on the low-voltage setting.

Dr Peyton and Dr Siegel have disclosed no relevant financial relationships. Gregory Conley is an employee of the American Vaping Association.

N Engl J Med. Published online January 22, 2015. Abstract

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