The case against chlorine-washed poultry has not been about any risks in that process itself, but that its use as a standard treatment masks, or potentially could mask, lax husbandry during the animal’s life. One of the main differences between practices in the UK (and in this instance the EU has followed the UK’s lead) and the US has been the regulated emphasis on the hygiene, health and welfare of farmed animals during their life. This in the belief that, quite apart from any ethical issues, the meat thus produced will be of better quality in every respect.
The problem is that there is no evidence pampering the livestock leads to higher quality/healthier meat. Producers have an incentive to want their livestock to be healthy as is. I’d need to see some kind of evidence that US FDA standards are not sufficient based on scientific evidence. I’m unaware that there is any....I tend to doubt it as there would be a large outcry in the US a la Upton Sinclair’s “the Jungle” if livestock conditions or the conditions of slaughterhouses and processing plants were unhealthy/unsanitary.