July, 2016:

Researchers found as e-cigarettes get hotter the more toxic emissions they give off

http://www.independent.co.uk/news/science/e-cigarettes-emit-harmful-chemicals-research-suggests-a7159171.html

E-cigarettes emit harmful chemicals with some models releasing more than others, according to a recent study.

Researchers at the Lawrence Berkeley National Laboratory in California found the disintegration of two solvents present in almost every e-liquid – the substance vaporised in e-cigarettes – leads to the emission of toxic chemicals, including acrolein – a severe eye and respiratory irritant – and formaldehyde – a cause of coughing, wheezing and nausea.

Published in the journal Environment Science & Technology, the study found emissions of toxic chemicals escalate as e-cigarettes get hotter with use.

Using a custom-built device that emulated realistic vaping, the study analysed three different types of e-liquids in two different vaporizers operated at various battery power settings.

One e-cigarette was a cheaper model with a single heating coil, the other was more expensive with two coils. Researchers drew on each e-cigarette by taking puffs lasting 5 seconds every 30 seconds.

Researchers used gas and liquid chromatography to discover what was in the vapour and found emissions levels increased dramatically from the first, initial puffs to later puffs when the device had reached a hotter “steady” temperature.

A single-coil e-cigarette operated at 3.8 volts emitted 0.46 micrograms per puff in the first five puffs, but at the “steady” state – after around 20 puffs – it emitted 8.7 micrograms per puff.

“When you apply the same voltage to the double-coil e-cigarette you see a lot less emissions,” said co-author and Berkeley Lab researcher Lara Gundel. “We think it has to do with lower temperatures at each of the coil surfaces.”

Assuming 20 puffs on an e-cigarette is equivalent to smoking a conventional cigarette, said Dr Gundel, the total emissions of acrolein for an e-cigarette are about 90 to 100 micrograms. Conventional cigarettes emit 400 to 650 micrograms of acrolein per cigarette.

Emissions of chemicals in e-cigarette vapour such as formaldehyde, acetaldehyde, and acrolein – all carcinogens or respiratory irritants – increased with usage.

“In some cases we saw aldehyde levels increase 60 per cent between cycles 1 and 9,” said co-author and Berkeley Lab researcher Mohamad Sleiman.

Significant levels of 31 harmful chemical compounds were found in the e-cigarette vapour.

Previous studies have found e-cigarettes contain toxic chemicals. In 2015, a study showed e-cigarettes emit formaldehyde, a carcinogen also found in cigarette smoke.

This latest study, however, found two chemicals never previously recorded in e-cigarette vapour – propylene oxide and glycidol – both of which are thought to be carcinogens.

Despite the findings, earlier this year a major report by the Royal College of Physicians concluded e-cigarettes are beneficial to public health and smokers should be encouraged to use them.

The 200 page report concludes that “among smokers, e-cigarette use is likely to lead to quit attempts that would not otherwise have happened”.

An estimated 2.1 million Britons use e-cigarettes; a figure which is steadily rising. Since their introduction in 2007, they have been marketed as successful tools to wean smokers off nicotine addiction as they reflect the sensation and practice of smoking while giving lower nicotine doses.

A study in March claimed almost 900,000 smokers in England used e-cigarettes to break their habit in 2014.

“Advocates of e-cigarettes say emissions are much lower than from conventional cigarettes, so you’re better off using e-cigarettes,” said Dr Destaillats. “I would say, that may be true for certain users – for example, long time smokers that cannot quit – but the problem is, it doesn’t mean that they’re healthy. Regular cigarettes are super unhealthy. E-cigarettes are just unhealthy.”

With age, heat, e-cigs emit more toxicants

https://www.sciencenews.org/article/vaping%E2%80%99s-toxic-vapors-come-mainly-e-liquid-solvents

Over the last three years, growing evidence has shown that electronic cigarettes are not the harmless alternative to smoking that many proponents have argued. Now, a new study traces a large share of e-cigs’ toxic gases to a heat-triggered breakdown of the liquids used to create the vapors. And the hotter an e-cig gets — and the more it’s used — the more toxic compounds it emits, the study shows.

“There is this image that e-cigarettes are a lot better than regular cigarettes, if not harmless,” says Hugo Destaillats, a chemist at Lawrence Berkeley National Laboratory in California. But after his team’s new analyses, published July 27 in Environmental Science & Technology, “we are now definitely convinced that they are far from harmless.”

Electronic cigarettes draw liquids over one or more hot metal coils to transform them into vapors. Those liquids — propylene glycol, glycerin or a mix of the two — are food-grade solvents laced with flavorings and usually nicotine.

The Berkeley team used two current models of e-cigs and three different commercially available e-liquids. The experimental setup mechanically drew air through the devices to create the vapors that a user would normally inhale.

Heating up

The higher an e-cigarette’s voltage, the more toxic aldehydes it produces in each puff of vapor. Once a certain threshold is hit, each voltage increase produces a disproportionate increase (see last bar) in acrolein, acetaldehyde and formaldehyde, three of the most harmful compounds in the vapor.

Adapted from M. Sleiman et al/Environmental Science & Technology 2016

Toxic aldehydes (such as formaldehyde, acetaldehyde and acrolein) were at negligible levels in the starting e-liquids, Destaillats notes. But the chemistry of the vapors varied as the e-cig device heated up: The first puffs contained somewhat less of the aldehydes than later puffs.

The new data show that “through the process of vaping, you are generating almost 1,000-fold higher emissions of those same compounds. And that is from the thermal degradation of the solvents,” Destaillats says.

Some devices can vary the voltage used to heat their coils. Higher voltages produced hotter conditions and more of the toxic aldehydes, which are probable or suspected carcinogens. Acrolein is also a potent irritant of the eyes and airways.

With a rise from 4.3 to 4.8 volts, the jump in emissions “goes exponential,” Destaillats adds, particularly “for the three aldehydes that are among the most harmful compounds present in the vapor.” Users could inhale up to 165 micrograms of these aldehydes per puff, the study found.

In their first tests, the chemists used a new e-cigarette for each puffing session. But in a second set of tests, they used one device over and over at its high-voltage setting.

After the ninth 50-puff cycle, the toxic aldehyde emission rate had climbed by another 60 percent. This was consistent with a buildup on or near the heating element of what has come to be known colloquially as “coil gunk,” the researchers say. “Heating these residues would provide a secondary source of the volatile aldehydes.”

The data on changes in the vapor composition of “aged” e-cigarettes “is something new,” notes toxicologist Maciej Goniewicz of the Roswell Park Cancer Institute in Buffalo, N.Y. And using a better analytical technique than others have employed, he says, the Berkeley team turned up new toxicants — such as propylene oxide and glycidol — which neither his group nor others had detected in e-cig vapors.