Back in the late 70s, the US Navy went from issuing dungarees to something they called "Utilities" Dungarees were cheap all cotton material non-dress uniform for doing day to day work. Utilities were 1005 synthetic replacements. Toward the mid 80's the Navy determined after a number of fire-related adverse outcomes that Utilties were not suitable attire, and switched us back to dungarees again.
Personally, I found either one to be worthless. When we fought a mainspace engineering fire, I was glad I was wearing the cotton; the synthetics would never have made it.
In Baghdad, all we wore were synthetics. Cotton under the body armor was just too much. You sweat too hard, and the synth would pull the moisture out to exposed areas better, the cotton stuff would stay wet against your skin to the point of wringing wet.
Other than firefighting, I've never had an occasion where synthetics would've been that hazardous.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)