I've tried PGA extracts of purple tulsi, AKA holy basil as well as rooibos using methods similar to Str8visions PGA extraction method for tobacco. I have a coffee extract I haven't filtered yet, as well as cinnamon and clove. Those are in separate batches of PG as well as VG/PGA for future experiments.
From a flavor standpoint, I found the teas similar to what one might drink. I think it's potentially an interesting avenue of approach. My thought is that it's probably safer than tobacco, but this is really just guesswork on my part, based simply on the fact that tobacco products ingested orally have carcinogenic properties, whereas tea does not.
That said, I haven't found any firm information on it. I've read about occupational exposure to tea dust and it's association with respiratory disfunction. You can Google tea dust inhalation for more information. Of course, we're talking dust in this case, not heated vapor.
Unfortunately, I think it's one of those things that if you proceed, you are the guinea pig/pioneer. When one speaks of tea and coffee, there are a lot of different teas and coffees with potentially different amounts of organic compounds which may or may not have a negative health effects. There simply aren't longterm studies on the subject.
Although people are comfortable extracting tobacco or other things, I believe the jury is still out on the longterm health effects. I think for many people, it's all about relative risks. If it keeps them from smoking, the consensus is that it's better.
Regarding green tea specifically, I read something interesting about aerosolized EGCG and tea catechins used for potential cancer inhibitory treatments.
Lung Cancer Inhibitory Effect of Epigallocatechin-3-Gallate Is Dependent on Its Presence in a Complex Mixture (Polyphenon E)
I personally won't be inhaling green tea extracts for medicinal purposes. But I think maybe some day there may be more information on the subject.
Str8vision touched upon the idea that extracts that contain oils may be undesirable. I know also that sugars can be undesirable. I've tried vaping a DIY fruit extract and it tasted like something that was held over a campfire on a stick too long.
One quick alternative idea for you. What about a commercial coffee extract? These would be lab tested and only contain the desired flavor components, and not unintentional byproducts from DIY extractions.
I can't speak for commercial green tea extracts, but I can only guess there has to be something out there.
A final idea. If you were to explore this DIY route, you might want to research what people have smoked in a pipe. I know there are some herbs that have traditionally been used as a tobacco substitute. Perhaps there is more longterm data on those.
