Seems it is still used, I was under the prior understanding that farms were phasing it out as it's far more corrosive and incurs a larger maintenance cost. I can't find anything more on the topic other than that industry page claiming about 10% from 2015.

> 2. There is no evidence that the absence of antimicrobial treatment of chicken carcasses yields "measurably worse health outcomes", as you say.

I have been consistent in claiming that the US supply chain has issues EU/UK don't appear to have. Increased salmonella concentrations are absolutely a health risk and these treatments show large measurable reductions on the level of surface salmonella. There's more than a few studies published in recent years covering outcomes on on chlorine, lactic acid, peracetic acid, SBS, and other rinses. I've never claimed that it's a magic bullet, only that all the data says 'it helps'.