In fact, there has never been an explosion that can be
verified as having been caused by a cell phone.

I can't cite any examples, but I'll give you a scenario where a cell
phone could cause an explosion: What if the phone is set to vibrate
mode and you happen to receive a call while in the presence of
explosive vapors? The vibrator is usually a small DC motor with an
eccentric weight on the shaft - and DC motors make sparks!.

On the subject of static causing explosions and fires - there is
definitely a hazard. I have seen several video clips of it happening.
Static typically involves quite high voltages but only a tiny amount of
current. Even though something like a plastic can is a poor conductor,
there is some ability to pass current (perhaps aided by contaminants on
the surface). So if you "ground" the item in question any difference in
potential between it and other "grounded" things in the vicinity will
tend to be reduced. Personally I take the advice and place gas cans on
the ground when filling them. It's also a good idea to touch some part
of the can (other than the spout) to the machine you are refuelling
before starting to pour.

David Johnson