(Sure, Phosgene is manufacturered in large quantities for use in the
manufacture of certain plastics, and shipped around the country in
tank trucks with the standard "corrosive" placard. I did some lab
testing on a phosgene compressor seal long ago, and the co-worker who
installed it in the field reported that phosgene makes cigarettes
taste terrible.)
The specification we are following is from the US Army. They have
more funding to pursue these tests than we do. Specifically it says
PVC=No, Teflon=Yes. My guess would be that PVC is toxic at a lower
temperature or in a higher lethality than Teflon.
But my original question was about irradiated polyolefin insulation.
Where does that fit on the safety spectrum?
I would guess that polyolefins, consisting only of hydrogen and
carbon, would be fairly good as far as smoke toxicity. But this is
precisely the sort of guess I don't think you should be basing design
decisions on. What does the Mil-Spec say? I would expect major wire
manufacturers to be able to answer questions about what insulations
meet your specifications; possibly you could call Belden or your
preferred wire supplier and discuss the matter with their applications
engineering department.