Here’s a secret: butane canisters are lined with a thin polymer or metal coating to prevent any reaction between the gas and the metal. The gas never touches the can’s walls in a liquid state for long. Even if it did, the steel is food-safe.
The nozzle is the only part that gets hot, and that’s made of brass or stainless steel. Don’t lick it (obviously), but it’s not going to leach anything scary into your food. Regular torch cleaning prevents buildup of carbon specks.
One major safety note: never store your butane canister in direct sunlight or above 120°F (49°C). That includes your car’s glovebox in summer. It’s not unstable, but it is pressurized, and heat is its kryptonite.
