Decomposition of VG to acrolein

[kinabaloo]

Pete - That's a true observation.

Nuck - I've seen that sentence on one of the reports. To be fair, it's nearly impossible to declare that something is not present. But the results are far from conclusive, especially given that the amount present would be on the edge of detectability using that technique. A specific test would be required.

We shouldn't get too overly focused on acrolein. The point is that a degrading deposit is not a good thing and best avoided.

I believe food-grade glycerine is usually vegetable derived; chemically it is identical, but remaining impurities might differ. Glycerine 'impurity' is mostly just water, as far i could tell. PG however is derived from natural gas, the petrochemical and it is possible that a trace of ethylene glycol remains as it is difficult to separate these two (I wonder if this impurity causes the allergy); to get pharmaceitical grade certification the amount would be tiny. PEG can possibly contain traces of dioxanes. There are limits to purity. But avoiding deposits from VG decomposition and dry residues from flavorings is readily possible.

I considered the impurity angle for the deposit formation but it cannot account for it; research found it is almost entirely water.

Exo's equipment is certainly up to the task of comparing PG and VG and a very marked difference was found.

There is still the possibility, if rather unlikely, that the decomposition will not take place when the fraction that is VG is below a certain threshold. That's worth looking into. I like VG - it's easy to get and food derived. But results are results.

 

[Nuck]

Pete - That's a true observation.

Nuck - I've seen that sentence on one of the reports. To be fair, it's nearly impossible to declare that something is not present. But the results are far from conclusive, especially given that the amount present would be on the edge of detectability using that technique. A specific test would be required.

We shouldn't get too overly focused on acrolein. The point is that a degrading deposit is not a good thing and best avoided.

We agree the results are not yet conclusive, I think it's on the next step we have the disagreement.

To shorten this I'll post the entire argument as a whole. Here is how I see it:

VG has no known issues and no suspected hazards outside of acrolein. A deposit may reduce atomizer life but given that the buildup is heavy when using either PG and VG based liquids with atomizers it is likely the deposits are the results of flavors and cart material. I have seen the conjecture that VG may reduce atomizer life but have seen no evidence, even anecdotal on these forums that would support such a theory.

Then we have the health issue. This is the real issue that concerns all of us. Like everyone else, I just want to make sure I really am vaping the safest transport for my nicotine.

For PG:

The previous lab report by TW and the followup from the same lab from Gamucci listed the following concerns:

"However, it is listed as a suspected respiratory toxicant, suspected skin or sense organ toxicant, suspected neurotoxicant, and a suspected immunotoxicant."

For VG:

"Non Hazardous"

Now I understand the concern with VG as it relates to acrolein but as previously quoted in the Intellicig lab report:

"In addition to these materials, an example of cigarette smoke from the cigarette was subjected to LCMS, GCMS, and NMR to test for the possibility of acrolein structures which as of the time of writing we are pleased to report have not been identified."

So based on the lab reports, VG is currently looking to be a far safer transport. I worry that users seeing what appear to be scientific tests on these forums will be led towards a less safe choice based on what in reality is nothing more than talented users using inadequate gear, with no way to quantify or even reproduce the results.

I really do understand the motive, but I think the care should be taken to ensure users are not scared away by some of the conclusions that seem to be drawn here without any real proof.

 

[surbitonPete]

I wouldn't say there is a 'long' list of concerns with PG.....in fact there is a fair amount of 'conjecture' about potential health benefits but at the same time there is no doubt that a few people have reported experienced some health problems with it ......on the other hand I don't know of anyone at all reporting 'any' problems with VG. That would suggest that VG is the best choice.....Personally I haven't got a clue which one is really the best in the long term. At the end of the day it's a personal choice based on the known facts as well as the conjecture. I certainly wouldn't be willing to champion one over the other.
One of the reasons I became interested in this forum was because people were collating all the know facts and the conjecture....and I wanted to know it all.

 

[kinabaloo]

Nuck - I would phrase it all rather differently. In short, PG is the original choice and probably for good reason (despite being a little more expensive than VG). VG is more widely tolerated it seems, but is not heat stable.

So it would be nice to understand more why some people don't do well on PG; is it a particular source / an impurity, or just one of those things we cannot change.

Investigate alternatives such as PEG-400 and dipropylene glycol.

Again, don't focus on acrolein. The fact is that VG creates a deposit (while PG, and probably dipropylene glycol and PEG-400, do not).

Changing flavorings and nicotine preparation to avoid dry residue, together with a non-VG base (or a reduced % VG base if that is found deposit free) would offer a deposit free juice and that's the way to go. Even if no acrolein is released, burning organic deposits on the coil will be creating other nasties and best avoided, as we can do.

 

[Nuck]

Nuck - I would phrase it all rather differently. In short, PG is the original choice and probably for good reason (despite being a little more expensive than VG). VG is more widely tolerated it seems, but is not heat stable.

So it would be nice to understand more why some people don't do well on PG; is it a particular source / an impurity, or just one of those things we cannot change.

Investigate alternatives such as PEG-400 and dipropylene glycol.

Again, don't focus on acrolein. The fact is that VG creates a deposit (while PG, and probably dipropylene glycol and PEG-400, do not).

Changing flavorings and nicotine preparation to avoid dry residue, together with a non-VG base (or a reduced % VG base if that is found deposit free) would offer a deposit free juice and that's the way to go. Even if no acrolein is released, burning organic deposits on the coil will be creating other nasties and best avoided, as we can do.

If you look at the tests (I didn't interpret as it's not my field but another member from the forums did) you will see that the vapour was extremely clean and there was no indication of other components being produced. I believe he called them clean phase shifts but I will check with him. There was a large unlabelled spike but it turned out to be a test material (again I will get the name).

The deposits on the coil are not a concern in and of themselves unless you are worried about atomizer life. In terms of health, the components in the vapour are the only real concern and the only lab reports on vapour we have gave it a clean bill of health.

I think we have to separate the atomizer life issue and the healthier option issue as they seem to overlapping in the debate.

 

[kinabaloo]

Nuck - the issues are absolutely linked. The deposit is not just things that didn't evaporate - they are burned residues of those things. Plus, in the case of VG, extra things. And while all this burning takes place, noxious gases will be released with the vapor.

The vapor test results are not clean - they even had to infer the presence of glycerine and nicotine (I quoted the paper earlier).

 

[Nuck]

Nuck - the issues are absolutely linked. The deposit is not just things that didn't evaporate - they are burned residues of those things. Plus, in the case of VG, extra things. And while all this burning takes place, noxious gases will be released with the vapor.

The vapor test results are not clean - they even had to infer the presence of glycerine and nicotine (I quoted the paper earlier).

Rather than give 2nd hand information I will contact the forum member who analyzed the results and ask him to post the basis and reasoning behind is conclusions. Should be interesting.

I do disagree with one of your arguments. I think any components of consequence produced during vaporization would show on the tests. I'm not sure that something could be completely undetected and then show up later due to 'buildup' on the coil.

 

[kinabaloo]

I do disagree with one of your arguments. I think any components of consequence produced during vaporization would show on the tests. I'm not sure that something could be completely undetected and then show up later due to 'buildup' on the coil.

I didn't say that. I am not saying it will show up later.

It is undetected either because it all reacts/degrades/polymerises at the coil, is too small in quantity to detect or (most likely) the test can't easily distinguish between what is present. Again, even the presence of glycerine had to be inferred from the data.

However, re 'show up later', though the degradation on the coil will be partly almost instant, it might partly take place over hours. To be fair, a test would use an atomizer that has been used for at least an hour or two.

It's not a matter of buildup.

I'd say there are some noxious things in the results that I can infer from the sheer noise of it when compared to the prevaporised results. I bet the same test done with PG would show a lot less 'noise'.

Let's see how it pans out over the coming weeks. We will gain more evidence and insights and test results.

 

[Letzin Hale]

I am afraid one or two lab tests aren't enough to prove that under all vaping circumstances there is no acrolyn produced.....people are using higher voltage batteries...changing temperatures ....there are so many variables....to decide that a couple of reports makes you certain that there is no chance of acrolyn being produced (because the reports were done by cleverer people than us) seems a bit naive to me. Still no one is saying it's at a dangerous level...we wouldn't be vaping it if we believed that.

The personal jibes from a couple of members (not you Pete) are like water off a duck's back to someone who grew up where I did and who attended the school of hard knocks. Calm your skin.
I never made any claim that the tests offered definitive proof, but merely pointed out that they should not be easily discounted for obvious reasons.
I know now what I am dealing with so I will leave the thread to their devices.
Although further tests are required, it would appear on available evidence that acrolein presents a minimal risk if any at all.
Some research indicates that acrolein could have cancer inhibiting properties, that's a new slant on the 'bad boy'.

See:Isophosphamide as a New Acrolein-producing Antineoplastic Isomer of Cyclophosphamide

"Isophosphamide, a new experimentally effective antitumor
agent, generates the cytotoxic aldehyde acrolein during its in
vitro oxidative degradation by either liver microsomes or
chemicals. The patterns of formation of acrolein by hepatic
microsomal preparations from isophosphamide and from
cyclophosphamide are similar, although larger amounts of
acrolein are obtained from the latter. As most of the biological
activation of cyclophosphamide takes place in the liver
microsomes, it is suggested that acrolein might participate in
the antitumor effects of these two drugs."

Now that some progress has been made on the acrolein front, what about the other properties of Humectants? PG VG PEG SEG, are they really safe or could we be at risk of them contributing to any of the following?
Chronic obstructive pulmonary disease (COPD)
pneumonia;
asthma;
bronchiolitis;
upper respiratory tract infections.
other acute respiratory tract infections;
Pneumoconiosis and Silicosis
Allergic rhinitis
Acute Respiratory Distress Syndrome
Bronchitis
Influenza
Pneumonia
Emphysema
Sarcoidosis
Pleurisy
Lung Cancer

The first paragraph below illustrates how one school of thought thinks that VG is okay when used as a humectant in skin care products, but further evidence contradicts that.

"However, regardless of their ability to moisturize, some humectants are harsh industrial chemicals not suitable for natural skin care. Propylene glycol, for example, is used in anti-freeze, brake fluid, paint and floor wax. It is also used in cosmetics and lotions because of its humectant properties - it enhances absorption of moisture and also facilitates the absorption into the skin of the other ingredients. However, propylene oxide, of which propylene glycol is a derivative, is known to actually cause eczema, rashes and dry skin and is classified as a carcinogen in EPA’s Toxic Release Inventory. Per the EPA, if it is inhaled or ingested, or makes eye or skin contact, it can irritate the eyes, upper respiratory system, lungs, and skin.
When choosing skin care products, you should always ensure that humectants are in the ingredients. However, make sure to stay away from propylene glycol. Instead, choose products with vegetable glycerin, vitamin E, panthenol (a form of pantothenic acid - Vitamin B5), collagen and elastin. These humectants are safe and natural and provide the dry skin care you need without causing further damage."

"Propylene Glycol: The most common humectant and carrying-chemical in cosmetics. It is a very inexpensive neurotoxic petrochemical mix. It is also used in antifreeze, airplane deicers, hydraulic brake fluid, varnish, and pet food. It has a small molecular weight, and therefore easily penetrates the skin. It accumulates in the heart, liver, and kidneys (where it can cause damage.) Propylene Glycol can depress the Central Nervous System, cause gastrointestinal disturbance, and induce nausea. It weakens the immune system and cellular structure. The MSDS on this chemical warns to “avoid contact with eyes and skin”, and suggests the use of safety goggles and other protective gear. Commonly found in deodorants, this substance may be contaminated with 1,4 dioxane.

PEG (Polyethylene Glycol): A petroleum based softener and binder that is widely used in cosmetics. A known irritant and potentially toxic if too much is absorbed into the body."

From: Health Essentials - Myths

MYTH #2: GLYCERIN — A beneficial humectant.

Glycerin is a clear, syrupy liquid used in almost all soaps and lotions (even the "natural" ones), and has many other uses. It's made by chemically combining water and fat. The water splits the fat into smaller components: glycerol and fatty acids. It improves the spreading qualities of creams and lotions, and prevents them from losing water through evaporation.

A solvent, humectant and emollient used in many cosmetics, glycerin absorbs moisture from the air, helping to keep moisture in creams and other products, even if the consumer leaves the cap off the container (Winter).

That sounds fine; however, glycerin also has a tendency to draw water out of the skin (see more at Myth #3). Unless the humidity of the air is over 65%, glycerin will pull the moisture out of the skin, drying you from the inside out (Chase).

MYTH #3: HUMECTANTS — Beneficial for drawing moisture to, and aiding in the moisturizing of, the skin.
Most moisturizers contain humectants. These are compounds that act as water attractors. In either a natural or synthetic form, they are used to prevent water loss and drying of the skin, as well as to preserve the moisture content of materials, especially in hand creams and lotions (Winter), giving them a smooth texture.

However, while touted as great moisturizing agents because of their ability to draw moisture out of the air, often they're actually pulling moisture out of your skin (Valmy).

Here's why: Humectants are in search of moisture. If that moisture can be absorbed from the environment, fine; but if the environment is too dry, and there is no environmental moisture to be had, a humectant will get it from the next best source — your skin.

This means that humectants, including propylene glycol and glycerin, while apparently effective when used in areas with high humidity will, if used in an extremely low humidity atmosphere (defined as below 65%) — such as in an airplane or even a dry room — can actually take moisture from your skin. And so, the ingredient used to help your skin remain moist is actually doing the opposite (Brumberg).

MYTH #11: PROPYLENE GLYCOL (PG) — A beneficial humectant.

Propylene glycol is a moisturizer, the most common moisture-carrying vehicle, other than water, in cosmetics. It has better permeation through the skin than glycerin, and is less expensive. However, it has been shown to provoke acne eruptions (Chase), and been linked to other sensitivity reactions. Its use is being reduced, and is being replaced by safer glycols (Winter).

The Material Safety Data Sheet, Propylene Glycol USP, shows: "over-exposure to this material (or its components) has apparently been found to cause the following effects in laboratory animals: liver abnormality and kidney damage." (ARCO Chemical Company).

And finally: Humectant additive

Let the debate expand.
Alan.

 

[exogenesis]

Oh well, sorry about the abruptness last night,
had just read too much of the 'no acrolein present' assertions.
Glad to see some interesting info in that last post.

Pure PG : still no deposit on coil after about 22 ml 'vaped',
will post some piccies tonight in the relevant thread.

PEG-400 (= PEG-8), seems is not orderable through Boot UK,
from online-reagent shop cost is £28 + £16 courier for 1 litre, sounds a bit expensive,
same price for PEG-300 (=PEG-6).
Anyone know where to get some in the UK ?

Found something sort of interesting about glycerol, freezing/melting point is 18 celsius,
presumably the reason it doesn't freeze on a cold day, is due to other things in the mix.

PEG-400 boils at 290 celsius,

& estimates from flash points:
PEG-300 around 220
PEG-200 around 130.
So maybe PEG-300 would be better than PEG-400 for our use?


Mineral oil appears to come in 3 classes with boiling points of
287, 356 and 390 celsius, also might taste a bit like petrol ?


Nuck,
would be very interested in that interpretation of the 'smoked' eliquid GC trace.

 

[kinabaloo]

Interesting chart Exo; I think this % split with water. If there is something similar wrt boiling point, there might be a % of VG that does not lead to a deposit. A little bit of a long-shot but just might be the case. In this case, i would hazard that it would be when VG is a minority fraction.

Found that PEG is not broken down to EG in the body, so that's good news.

As is the no deposit with PG

 

[kinabaloo]

ps: It makes sense to go with the lower B.P but last night on looking into this I found the 400 version to be more well-tolerated. Seems Sedansa have done their homework

However, that was a cursory skim of information; worth looking at again as the lower BP would be most welcome.

 

[exogenesis]

It seems a small amount of water reduces the boiling point of
glycerol markedly.

The 30ml glycerol + 4 ml water I was using, that produced
about 1 amount gunk from 1000 amounts of glycerol should
have had a boiling point of only 133 celsius.

Don't know if you get 'partial distillation' though,
i.e. does it go back to 100% glycerol during the evaporation process?

Didn't stop it degrading though,
but possibly only that part in contact with the hot coil was making
the 0.1% denatared gunk, the majority boiling off as vapour ?

Might be worth testing other ratios to see if it make less or more
gunk with more/less water.

 

[kinabaloo]

Exo - good find, very interesting - far from linear and suggests a test with 50% VG (comon usage) well worth doing. Could still be fractonal distillation effects and temperature variations sufficient to still cause a deposit. But only one way to find out ...

I think we can expect less than half the quantity of deposit though, perhaps only a 1/4 or even less. Would be nice if it turned out to be close to zero

ps: ethanol might bend that curve even more I wonder ?

pps: heating a water/VG mix (50/50) on a teaspoon: separates the two very visibly; all the water evaporates first. The whole mix looks to be boiling but only in the second half, time-wise, does the characteristic fog appear. Flash heating of a tiny amount would be expected to behave very differently, but perhaps not.

ppps: judging from the 'noisiness' of the vapor test result chart, there might be an unknown number of gaseous units produced too.

 

[kinabaloo]

A note:

Regarding VG and atty voltage.

The boiling point of VG is considerable higher than PG (and perhaps its heat capacity also). Have been wondering on and off about the benefits or cons of running attys at a higher voltage. When a VG based juice is used there just might be an advantage in a higher voltage. The reasoning being as follows. If the temperature reached is lower than for ideal flash heating, a portion of the VG might remain after an activation (puff) as the juice partially undergoes fractional distillation. This increases the concentration of VG (%wise) of the juice on the coil for the next puff, raising the BP for the mix; in other words it is self-reinforcing. The temp is just enough to favor decomposition moreso than evaporation and the effect is increased deposits; whereas a higher voltage, higher temperature, setup would maximise vaporisation (but some decomp of VG would still occur).

Separate issue but worth noting:

Higher voltages are also more likly to burn the dry residue of the juice (principally the flavoring). This could cause noticeable bad taste/smell, but also potentially completely burn off some of the deposit reducing the deposit quantity.

 

[kinabaloo]

Well, as I've only lurked while Pete, Exo and Kin have been doing their research (I think I piped in only once or twice to thank them for what they have been doing), I want to again thank them. They are not suppliers, they are not being paid for the research they are doing on behalf of all of us.

Just want to thank you guys again and hope you continue to post your unbiased results. Cheers!

Apologies for the delayed response Jacksid. Much appreciated

I am commited to vaping and only seek to improve both the vaping experience and our understanding of it. If we can conquer the deposit issue (and intolerance issues), and I believe we can, then this will be a big step forward. It feels great to play a small part in something that could touch on so many lives - if vaping can more widely replace smoking as it reasonably should. We might have to say farewell to VG, but there are alternatives. Dry residues from flavorings are the big factor remaining; and it could be worked out in just days once the issue is addressed.

The dry residues were known about before i even got into this, but so far little thought or action seems to have gone into addressing it. The 'well, attys are fairly cheap, no big deal to replace them every so often' is reasonable to a point - but involves accepting slowly diminshing performance, bad tastes and unknown toxins (tiny though they may be, but inhaled everyday). As we can eliminate the problem we should aim to do so. Attys will still not last forever, but could well last a lot longer.

 

[JaneDoe]

Can anyone put this glycerin fear in perspective? What do you think is the bottom line here? Fear of acrolein/VG is the reason I am waffling and keep going back to analogs and I can't vape PG.

Any ideas about comparing the analog risks to the VG risks? I know it's a great unknown, but what are your thoughts? Is acrolein DEFINITELY present in VG vapor or possibly? If it is definitely in there is it a sure health risk or a potential risk?

Cigarette smoke definately does contain acrolein. So does air pollution.

 

[kinabaloo]

Cigarette smoke definately does contain acrolein. So does air pollution.

That's true. And most cigarettes contain glycerine as a humectant (probably explanatory, possibly coincidence)

It's not yet confirmed that any acrolein gets into the vapor; but there probably is a bit, but likely not too serious - long term maybe, but no cause for alarm, just needs more investigation.

PG is good to go. PEG-400 is looking good too and might be a suitable alternative to VG for those with PG sensitivity.

ps: it feels very awkward to make any statement about such matters. I can only offer a best guess. There might well be an issue but it's not something that deserves panic. Could be worse than I think (unlikely as acrolein has a noticeably terrible smell) or no real problem at all.

But what we do know now for sure is that VG produces far more deposit in the atomizer (not a good sign - as well as not good for the atomizer).

pps: if the point is that analogs are surely worse, it's easy to agree with that. So if you've switched from analogs, there's every reason to not be too worried. Give it a bit more time for the 'bottom line'; we can make vaping even better.

Hmm, now I think i'm perhaps being too glib. In simplest terms, 'i don't know'. Acrolein does appear in the Ruyan results (very small amount) and the tests where it is 'not detected' - well, don't read too much into that as even the nicotine had to be inferred. There probably is a tiny bit (the science suggests that) but there is a tiny bit in the air too, even in some foods.

For what it's worth, I am still vaping with VG. But I will also continue investigating this.

If PEG-400, for example, checks out well when Exogenesis tests that (and low dose VG still shows a problem), then it seems sensible to move from VG to that. Unfortunately it is not, as yet, so easy to get hold of for cutting at home.

 

[toughdiamond]

Hmmm.....does anybody know how to find out whether a particular nicotine liquid contains VG or PG? I'm using one that has very little in the way of manufacturer's info - it's quite nice but I'd like to know which type it is.

It's called e-liquid (by e-home: high-nicotine, Marlborough flavour), from Amazon. I can't post the link because I haven't made enough posts yet - I was just wondering if anybody knew, or whether there's a simple practical way of determining this just by observation.

 

[Sun Vaporer]

Hmmm.....does anybody know how to find out whether a particular nicotine liquid contains VG or PG? I'm using one that has very little in the way of manufacturer's info - it's quite nice but I'd like to know which type it is.

It's called e-liquid (by e-home: high-nicotine, Marlborough flavour), from Amazon. I can't post the link because I haven't made enough posts yet - I was just wondering if anybody knew, or whether there's a simple practical way of determining this just by observation.

Tough--Unless it is made by Johnson Creek, it is more then likey PG--only JC has the NON-PG option that I am aware of--most of all the rest are PG----Sun