Fuel used in the F-16s EPU. When EPU is activated (which it is for many inflight emergencies), fire crew in hazmat suit has to check the aircraft for hydrazine leaks ofter landing before anyone can approach the aircraft. There is also a procedure for extracting the pilot on 100% O2 if a leak is present.
For the nations that have use a brake chute on the F-16, that has to be treated as hazmat until the aircraft is checked for leaks as well.