It is strange! It's a recent thing in the US, yes. Probably in the past 4-5 years nearly all major brands put some sort of special chemical that gives it 'moisture wicking' (usually in partnership with Dow or 3M).
I just bought some new underwear from Marks & Spencer in the UK which has their "Cool & Fresh" treatment. I haven't worn it yet but this thread is putting me off.
M&S publish a Manufacturing Restricted Substances List [1] for their suppliers, which seems to ban the use of all per- and poly-fluorinated chemicals in the manufacture of textiles for them.
Either I'm misunderstanding, or some of these underwear treatments don't involve PFAs. Who knows what they use instead?
None of the brand I wear (HOM) seem to be and I don’t remember that being mentioned on any pack of underwear I purchased the last 40 years.
Is it an US thing?
(and yes, I’m posting about my underwear on hacker news. weird.)