Far from posing a threat to our health, the propylene glycol in e-smoking liquids might help keep us healthy. It would accomplish that by its germicidal action. It kills many of the major bacteria that threaten lung entry into our bodies.
Until yesterday, I was unfamiliar with this potentially beneficial consequence of propylene glycol vapor.
Back in the late ’30s, researchers at the University of Chicago stumbled onto its effectiveness as a germ-killer, as related in this Time magazine story from Nov. 16, 1942:
"A powerful preventive against pneumonia, influenza and other respiratory diseases may be promised by a brilliant series of experiments conducted during the last three years at the University of Chicago’s Billings Hospital. Dr. Oswald Hope Robertson last week was making final tests with a new germicidal vapor 聴 propylene glycol 聴 to sterilize air. If the results so far obtained are confirmed, one of the age-old searches of man will finally achieve its goal…
"…the researchers found that the propylene glycol itself was a potent germicide. One part of glycol in 2,000,000 parts of air would 聴 within a few seconds 聴 kill concentrations of air-suspended pneumococci, streptococci and other bacteria numbering millions to the cubic foot.
"How did it work? Respiratory disease bacteria float about in tiny droplets of water breathed, sneezed and coughed from human beings. The germicidal glycol also floats in infinitesimally small particles. Calculations showed that if droplet had to hit droplet, it would take two to 200 hours for sterilization of sprayed air to take place. Since sterilization took place in seconds, Dr. Robertson concluded that the glycol droplets must give off gas molecules which dissolve in the water droplets and kill the germs within them.
"Dr. Robertson placed groups of mice in a chamber and sprayed its air first with propylene glycol, then with influenza virus. All the mice lived. Then he sprayed the chamber with virus alone. All the mice died."
The complete Time story can be read here: Air Germicide - TIME
In a scientific summary of the discovery, it was noted that "Tests on possible deleterious effects of breathing propylene glycol containing atmospheres over long periods of time are being carried out."
Those tests were done and a second summary report on propylene glycol vapor was released:
"Propylene glycol is harmless to man when swallowed or injected into the veins. It is also harmless to mice who have breathed it for long periods. But medical science is cautious 聴 there was still a remote chance that glycol might accumulate harmfully in the erect human lungs which, unlike those of mice, do not drain themselves. So last June Dr. Robertson began studying the effect of glycol vapor on monkeys imported from the University of Puerto Rico’s School of Tropical Medicine. So far, after many months’ exposure to the vapor, the monkeys are happy and fatter than ever. Dr. Robertson does not expect mankind to live, like his monkeys, continuously in an atmosphere of glycol vapor; but it should be most valuable in such crowded places as schools and theaters, where most respiratory diseases are picked up."
The monkeys lived in enclosures filled with propylene glycol vapor. No deleterious effect was ever reported. And the concentrations of PG we inhale on a regular basis surely must equal the amount inhaled by the monkeys for this test. Obviously, no scientist saw a time when a device would atomize a PG mist that would then be inhaled for fun. But time and technology has given us the electronic cigarette. With each inhalation, we are washing our lungs with a germicidal agent used today in some "air sanitizers".
Glycerine, by the way, has some germicidal impact, but not, apparently, to the degree provided by inhaling propylene glycol vapor. Glycerine is now used by dairy farmers to help prevent bacteria entering a cow’s teats after milking. Glycerine both softens the teats and kills bacteria.
One more quote on PG: "The vapour from as little as 0.5 mg of propylene glycol can kill nearly all the microorganisms in a liter of heavily contaminated air within 15 seconds."
The initial experiments with PG vapor were part of a search to find ways to create clean rooms, so the 1918 Spanish Flu pandemic that killed so many millions would never be repeated. Today, researchers have wondered online if propylene glycol vapor might not offer protection against a widely feared coming pandemic of bird flu, tagged H5N1.
Imagine e-smokers being healthier than non-smokers in such a scenario.|||wow!!..good find TB..that will become useful for me…no wonder I didn’t get the flu even though I was exposed badly during the recent bout of flu epidemic…and none of my e-smoking patients get sick too during that period…I was wondering about it , now at least I know why …Thanks Big Brother for all the hard work digging all this up, you are a true gem…..|||Wow TB your credit to this forum.|||That’s really good news TBob. I hadn’t reckoned on being healthier because of vapour. Is there a danger of the vapour killing off the friendly bacteria our bodies need for healthy balance? Maybe those are only important for digestion, I don’t know.
I noticed that ecig.com are selling ‘health’ eliquid that has vitamins or something in it. Is it likely that this is a good way to administer health supplements? I have to admit to being sceptical about this but if it does work then it’s another argument for our habit being a good one.|||Not to rain on good news, but hopefully htis won’t lead to superbugs that can’t be controled by antibiotics- probably it won’t, but bacteria are quite efficient at surviving crisis situations and readapting to hostile environments which would be provided by the PG sterilization- I know, I know, there’s always a fly in the ointment
However, protecting against sdomethign like virus like hte bird flu, or any number of lfues that are one shot deals,, thism ight just be the ticket hopefully|||Wow TB that is very impressive. Not only are we getting healthier - we are able to fight off some respiratory diseases.
A friend of my husband’s has COPD and I have been reluctant to recommend the e-cig to him but now I wonder if it could help?|||Holy Cow, TB, this seems like such a significant discovery that I’m having a hard time trying to understand why there hasn’t been a LOT more research on it. It would seem that it has kind of fallen between the cracks over the last 65 years. Unless, of course, there is something we don’t know yet. I keep scratching my head wondering if I am missing something.|||Thanks for this info Bob.
I have a stupid question though.
Is it not good to get a cold, and build up antibiotics in ones body?|||I spent most of yesterday, deep into the night, trying to find refutation of the reports. Didn’t find it. But at the time of that study, filling a room with propylene glycol vapor was a pretty fanciful idea. Impractical, to say the least. And we all know that it’s a fact that PG mists irritate some individuals. So studies moved on to other ideas. Today, we have a way to fill individual lungs — ours — with it. We can choose to use or not use.
For someone like Dr. Loi, it would add a second profound health reason for governmental agencies to support e-smoking:
1. If cigarette smokers moved to e-smoking, the reduction in disease and premature death would be staggering.
2. If propylene glycol vapor inhalation could prevent the full spread of some epidemic diseases, the savings — in misery and money — would boggle the mind.
We are going to need scientific reasons in support of the devices we now use and love. For me, however, this discovery of the studies provided a peace of mind that what we’re inhaling is not only safe, but could be beneficial. And Dr. Loi’s experiences with his patients during a flu outbreak would seem to point that way.
Let a new round of studies begin!|||Wow TB, what an awesome find!
The folks on this board never cease to amaze me with the amount of information that they scrap up…
Keep up the great work!
Phil great info. thanks TB and others.Tags: cigar, devices, ecig.com, Electronic Cigarette, eliquid, glycerin, glyco, Health, Safety and E-Smoking, medical, propylene