If it's dichloromethane (DCM), there shouldn't be any residue left to get into your body since it is so very volatile. But, naturally people are going to shy away from it because it's a chlorinated hydrocarbon with much greater toxicity than butane. With proper precautions, using the right kind of gloves, doing it outdoors (to avoid fumes... DCM is non-flammable), it would probably be fine. I used to work with it all the time while making, uh, other kinds of things. Yeah, it's carcinogenic, but you'd probably have to wash your hands in it to have a risk. Sadly though, all the people who blow themselves up just using butane demonstrate that the average person can't safely handle hazardous solvents. So maybe it's better that it doesn't catch on as an extraction solvent for this purpose.