Is it safe to consume lemon oil in the quantities that would be found in fried food? Could I fry corn tortillas, for instance? Would it fry? 
It would be dangerous to attempt to fry in lemon oil Lemon & other citrus oils are primarily (90+%) made up of Limonene, which has a "fire diamond" of 2-2-0:   Flammable The red 2 indicates flammability:  Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur (e.g. diesel fuel, paper, sulfur and multiple finely divided suspended solids that do not require heating before ignition can occur). Flash point between 37.8 and 93.3 °C (100 and 200 °F).  Limonene has a flash point of only 50°C (122°F). Canola oil & most "frying oils", by contrast has a flash point of closer to 315°C (600°F). Note that the "flash point" is the temperature where flames & active combustion take place. This is generally a good bit above the usual "smoke point" which is used to rank cooking oils. The flash point is the more dangerous temperature, as it equates to fire. This limits the feasibility of doing any cooking in citrus oils, due to their flammability. The high limonene content would render lemon oil to be a fire hazard well below "frying" temperatures. If you've ever seen a flamed citrus peel used as a cocktail garnish, you would have witnessed the flammability of citrus oils.  Health risk The blue 2 indicates a health risk:  Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury (e.g. diethyl ether, ammonium phosphate, carbon dioxide, iodine, chloroform, DEET).  As mentioned in another answer, even if flammability wasn't an issue, this could be dangerous. Contact with the skin can cause a rash ("contact dermatitis" if you're being technical about it) in certain cases. Even if it didn't burn at such a low temperature, the quantity of limonene needed for cooking, and the direct contact with your mouth while eating would result in a potentially dangerous situation. Small amounts are considered safe for consumption (and even used in supplements), but any significant quantity of lemon oil should not be consumed directly. 