In the late '60s I worked in a plastics resin plant which is probably an EPA Superfund site now. PG was a component of many resins. Ethylene Glycol is a constituent of antifreeze and leaking antifreeze has been responsible for many cat and dog deaths--they like the taste for some reason hence many states require a bittering agent be mixed in. Although FDA and other sources say PG is harmless to humans in small amounts, out of curiosity what is the purpose in mixing it with RC benzodiazepines?
Sorry man but I gotta say, none of that means anything. Except that most people don't know much about chemistry or cellular biology or metabolic pathways.
Something being used in antifreeze does not make it dangerous or safe in and of itself, it makes it nothing. Antifreeze is dangerous to consume, but that would only be relevant if the question were if antifreeze is safe to consume. So called poisons can be used in medicine, harmless stuff to humans can be lethal to some animals and vice versa. When it comes to chemistry, all that matters is what the chemicals being consumed are, how they're metabolized, in what quantity, and by what route. Through that and that alone determines the danger or lack thereof. Not out of context associations. Alcohol gets you drunk if you consume enough, vodka is generally alcohol plus water, so does water get you drunk? No. But it's the same sort of association. Water is also used as a solvent and for other purposes in numerous dangerous industrial applications. It's still irrelevant.
Likewise, is propylene glycol in some antifreeze products? Yes. Does that make it harmful? No. Does that make it harmless? No. It makes it neither here nor there. Same with resins. The presence of something in a product that can be harmful to human health does not by extension make that something itself harmful to human health.
Sorry to get on your case about this, but it's a bit of a pet peeve of mine.
So on topic, is it harmful? From what I can find, it's actually cats it's harmful too, not dogs, or humans either. I mean, ok, yes in very high quantities it can be harmful to humans and dogs too, but so long as you're not injecting the stuff and only using small amounts it should be fine. Google for more specific safe quantities.
It's however definitely not ok for cats. Much like how we can eat chocolate and all sorts of other foods that cats and dogs shouldn't, and they can eat food we shouldn't. We have different biochemical makeup. You could also he allergic to propylene glycol and find yourself in danger from consuming it when most people wouldn't even notice. Even within the same species this variation exists. Like how some people get no analgesic or other benefit from codeine and tramadol, because their dna lacks the information it needs to express the enzyme which converts those chemicals from their inactive original form into an active form. While the rest of us react normally.
Cats can't have it because their bodies won't break it down and dispose of it in a way that is harmless to their health. It will cause damage to their red blood cells (anemia) that wouldn't happen in humans like that from equivalent exposure.
In short. I'm sure you're fine OP. By all means google more for increased reassurance but I can if nothing else promise you that it being in other, much more harmful things, or it being harmful to some other mammals, is irrelevant. It is not harmful in those ways to us. We would need to consume a fuckton more to have a problem.
I mean it cant be good for you. Also what the fda considers small amounts and what we consider small amounts probably differs.
I very much doubt it does you any good either, but that doesn't by extension mean it does you any harm. This is such a case. In reality, everything we consume is all chemistry, and generally neither good or bad in such simplistic terms, but simply interacts or doesn't interact in our bodies in some way. That may range from beneficial to irrelevant to deadly and everything in between.
No it won't do you any good, it won't do you any of anything so long as you don't go injecting it or daring a friend to see who can drink the most.