Many racers use an oxy/acetylene torch. Quite often, a butane cigarette lighter is the weapon of choice in starting the fire. Most have heard the admonishment Dont do it!
They are unsafe for torch lighting because the pressure of the torch gases may overcome the butane pressure. If this situation occurs, the flame can enter the tank of the lighter. When near empty, the lighter is more dangerous. The lower butane pressure makes an accident more likely.
And yes, I have blown up a similar lighter. I was luckya welding glove and a fortunate angle protected me. The near-empty lighter fragmented itself, but plastic shrapnel may be the least of your worries.
With a simple modification, this type of lighter can be used safely and reliably. Note the photo of the lighter. You can see that a hacksaw cut has been made into the body. Do this away from any ignition source. The cut relieves any pressure, and in a few minutes the butane evaporated. You now have a sparker, not a bomband your smoking friends will keep you in torch lighters for years.