Cancer Risk

Cancer Risk Greater From e-Cigs Than Regular Cigarettes?

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.