American produced "n-butane" is ok, as the American standards for n-butane are strict. However, some other countries have much lower, if any standards for n butane. Eco green, out of Korea, for example, is 1 company that sells crap grade gas as "n-butane". I know of 3 companies that sell American n-butane by the can: Puretane (as mentioned here), Capitol (although I currently am unable to order from them), and Stok FYR USA N-butane (not to be confused with Stok FYR UK, which is NOT pure N-butane). Similarly, I would assume that any American made N-butane sold in bulk (by the multi pound cylinder), would be as safe as the brands sold by the can. According to a rep from Puretane, in the near future (if not by now), Puretane will be available for sale by the cylinder. Right now, Puretane is the purest brand of n-butane I know of... with no propane, and only a trace of iso butane. Is n-butane safe than propane or iso butane??... Well, Im not about to make that speculation... but, if organic status matters to you, then you would want to use only natural gases, such as n-butane, n-propane, n-hexane. Capitol apparently now sells a blend of n-butane and n-propane, which many people believe produces a better oil, but, once again, I currently have been unable to contact Capitol for an order. So, I can't verify the cleanliness of their gases.