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> > The other is almost entirely a mixture of Propylene Glycol and Vegetable Glycerin.

> What an extraordinary meaningless statement.

Not at all. The point being made is that we're dealing with a product composed primarily (99%) of two chemicals that are very clearly established as safe for human consumption (propylene glycol is commonly _injected_). As such, it seems unreasonable to assume absent evidence that the chemicals themselves would pose any significant threat to health.

That leaves other additives (which I noted) and the inhalation itself (which I also noted). As I stated in my previous comment, chronic inhalation of anything is likely to be bad for your health.

You really seem to have missed the context of the question I was responding to - it asked not about absolute safety, but rather safety relative to cigarette consumption.

Yes, as you note, there is always the potential for chemical reactions when mixtures are heated. Given the particular chemical composition and temperatures involved, I'm not personally concerned absent solid evidence. None of the byproducts listed in the study you linked appear particularly worrisome to me. Compared to cigarette, weed, or wood smoke, the contents of vaping such aerosols appears downright healthy. (Only in comparison, of course!)

Rereading my previous comment, something I failed to mention is the risk of inhaling things that are too hot. Depending on what temperature the aerosol is heated to, it could burn you internally (but then we're comparing this to inhaling burning plant matter, so... meh).

> I believe the current scientific consensus is that more research is needed.

To establish what, their precise negative health effects? Of course. But not to establish that they are safer than smoking cigarettes - there's absolutely no question about that.

Fog machines also use a glycol solution, and have been shown to be harmful. Thus vaping glycol may not be safe. https://www.cdc.gov/niosh/hhe/reports/pdfs/1990-0355-2449.pd...

The report you linked shows quite the opposite, actually. They concluded:

> Based on the results of this study, there is no evidence that theatrical "smoke," at the levels found in the theaters studied, is a cause of occupational asthma among performers.

That being said, chronic exposure is probably not good for you. From a health perspective, don't inhale anything other than air!

Asthma is only one of many possible heath impacts. It was associated with others, just not Asthma.

When compared to actors from the non-"smoke" productions, actors from two or more of the four productions utilizing theatrical "smoke" reported experiencing a significantly greater prevalence of nasal symptoms (sneezing, runny or stuffy nose), respiratory symptoms (cough, wheeze, breathlessness, chest tightness), and mucous membrane symptoms (sore throat, hoarseness, dry throat, itchy/burning eyes, dry eyes) during their performances for the week prior to the survey.

The final line is: The quantity and frequency of use of the various fogs during a performance should be minimized.

PS: A method of action was suggested to be the breakdown of glycol due to high temperature.

The report he cited proved his point.

Fog machines cause noticeable effects on breathing at significantly lower exposure levels and concentrations than vaping. IOW, it provides a lower bound for the purported safety of vaping.

Here is the conclusion of that study to save a click:

"Based on the results of this study, there is no evidence that theatrical "smoke," at the levels found in the theaters studied, is a cause of occupational asthma among performers. Some of the constituents of theatrical "smoke," such as the aerolized glycols and mineral oil, could have irritative or mucous membrane drying properties in some individuals. Therefore, it is reasonable to minimize exposures by such means as relocating "smoke" machines to avoid exposing actors to the direct, concentrated release of the aerosols, minimizing the amount of "smoke" necessary for the production, and using only fog fluids approved by the manufacturers of the machines. The glycols used should be at the level of "food grade" or "high grade." Glycol-based systems should also be designed to heat the fog fluids only to the lowest temperature needed that achieve proper aerolsolization. This would help to avoid overheating the fluid and minimize the generation of decomposition products."

What grade of glycol is used in a vape and are they required by law to state what grade it is?

Mainstream vendors use USP grade PG/VG and food grade flavouring (which can also include a small amount of PG or VG as a carrier)

The ingredients you list are safe for human ingestion. It doesn't follow that they are safe for inhalation.

Your point that they are likely safer than cigarettes is well taken, but your insistence on the ingredients being known to be safe to inhale is faulty.

> your insistence on the ingredients being known to be safe to inhale is faulty

Please reread my comment - I never claimed that. I very explicitly stated that inhalation of anything is likely to be bad for your health.

Is that what the marketers of the product are claiming as well? I see quite the opposite in the world around me. I feel the vaping industry is just as corrupt if not more so than the awful cigarette companies. https://www.cbsnews.com/news/juul-came-to-a-9th-grade-classr...

> very clearly established as safe for human consumption (propylene glycol is commonly _injected_).

Consumption, injection, and inhalation are very different routes of introduction to the body, and safe for any one does not imply safe for the others.

Many things that will cause no problem if injected or eaten will cause problems in the lungs.

>> The other is almost entirely a mixture of Propylene Glycol and Vegetable Glycerin.

> What an extraordinary meaningless statement.

>> ...except when it isn't

Emphasis on "except when it isn't" which highlights the other impurities that might be there. I found the comment to be useful at highlighting what it was designed to highlight - that the safety depends entirely on what's inside the carts. You have no guarantees with some suppliers what the heck's actually inside, and I think saying "it's fairly simple at the base, but rather complicated in reality" is quite helpful for framing.

Is the question "is vaping harmful?" (because it probably is) or "is vaping about as harmful as smoking?" (because it almost certainly isn't).

Unless vaping makes you smoke more compared to cigarettes. In my experience it does. Nicoteen us crazily addictive whatever form you provide it in people will do that too much. The more convenient the more they will do it.

I don't think even this is true. The nicotine isn't really what's bad for you, it's the smoke and 600+ carcinogens in cigarette smoke.

I'd imagine it'd be safer to vape 10x than smoke 1x.

That has not been my experience. With a cigarette, once you start it going, you basically need to finish the whole thing in a short period of time. If you really only wanted one or two drags, sorry, you're down for 10 minutes or so of smoke. (Or you could put it out and waste it, but given how expensive cigarettes are I doubt many smokers are inclined to do that.) With vaping, you can take one drag and put it down. Figuring out the volume or amount of nicotine consumed would be very complicated. And, of course, most of the negative effects of smoking have nothing to do with nicotine and it seems if there are negative effects from vaping, those will likely also not come from the nicotine itself.

I don't have time to thoroughly examine your references right now, but I can tell you off the bat that the third study is very poor - they measured vapor samples at 500°F and 600°F, which is substantially in excess of normal vaping temperatures and would almost certainly produce an acrid, foul-tasting vapor. The presence of CO in the vapor samples clearly indicates oxidation rather than vaporisation. Of course you get lots of nasty byproducts if you burn the liquid.

I think what's going on there is that one of the e-cigs they used had a configurable temperature (200-600 °F). I'll give them the benefit of the doubt and assume that they selected a reasonable one (they don't appear to specify in the methods).

Separately, there's the GC-MS machine - oven (30 - 220 °C ramp) and inlet (320 °C). This shouldn't be (much of) an issue though, as an inert carrier gas is used. Plus you always have controls, so if the GC-MS itself is tearing things apart it should hopefully be obvious.

That being said, I didn't see anything particularly concerning listed in their results (relative to recreational cigarette or alcohol consumption).

Recreational cigarette smoking? I've never met such a creature. Your either hooked or your not.

In the medical literature there is a classification referred to as a "chipper" who generally smokes only 1 or 2 cigarettes a week on average. Humans are many and varied.