Rustica is a wild tobacco, it is different from the domesticated species. It is used commonly by shamans in South America and by general public (mostly rural) in Vietnam. One of my college buddies from Vietnam smokes it out of a bamboo water pipe. I think its called “Thuoc Lao” there or something like that (not sure don’t quote me on the Vietnamese name).
It’s safe enough in moderation, I used to smoke Rustica cigars daily when I lived in Peru (its called “Mapacho” there). One thing i found is that it is considerably unpredictable in terms of strength. Some of the cigars I could smoke the whole thing and some would give me the wobbles 1/4 of the way into it. As cigars it was very smooth, delicious, and very mild smoke, often deceptively strong.
I bought some of Toque Rustica and I can take it pure with no problems but typically mix it 50/50 with other snuffs partly because I don’t want to develop any more of a nicotine tolerance and partly because its seriously dry and fine and does better mixed with a moister snuff.
Yes it does have higher concentrations of both nicotine (up to 9 times more) and MAOI-B (up to 100 times more) compounds than domesticated tobacco, the MAOI activity both potentiates and lengthens the nicotine effects as well so it is easy to over-do it when using Rustica.
Rustica was very likely one of the first tobaccos brought back by the Spaniards after their exploits in South America.
Just approach with caution and you’ll be ok.