(No relation other than read it)
The definitive book on the 1917 Bath Riots is Ringside Seat To A Revolution by David Dorado Romo.
> In the 1920s, the US Public Health Service began using small amounts of Zyklon B in the baths. The hydrocyanic acid was used as a fumigating agent at the El Paso disinfecting centers. A stronger version of the chemical was usually used to exterminate vermin, such as mice and rats. Health officials thought it would help kill lice, which carried typhus.
> Zyklon B is known to be fatal when absorbed through the skin in high concentrations. It's still unclear what lasting health impacts these baths caused on the Mexicans who had to endure them.
> In 1938, a German scientist by the name of Dr. Gerhard Peters wrote an article featuring photos of El Paso's baths and calling for the same tactics to be used in Nazi Germany's own disinfection chambers, known as Desinfektionskammern.
> Peters became the managing director of the company that supplied Zyklon B to concentration camps, and the chemical began to be used in Nazi gas chambers beginning in 1941. He was ultimately convicted of war crimes at Nuremberg, though he was retried in 1955 and was found not guilty.
> "Zyklon B was used in the baths but in very mild amounts compared to the Nazis," Levya said. "But the Nazis did learn about its use here on the border. So they were definitely studying the United States. They were looking at how laws dealt with race. They were taking a lot of cues from the United States."
https://www.businessinsider.com/bath-riots-el-paso-mexico-te...
https://www.zinnedproject.org/news/tdih/bath-riots
https://www.npr.org/2006/01/28/5176177/the-bath-riots-indign...
There are pictures of Mexican laborers being sprayed on the head with DDT in the 50s, however, and that for sure was not healthy (nor was the general treatment... humane to begin with). I don't think we need a very stretched comparison with the Nazis and Zyklon B to easily affirm that the US Army and the US Government did many times horrible things to plenty of people, including its own citizens (and especially the black ones, see e.g. the Tuskegee syphilis study)
Also, the US has fully destroyed its entire stockpile of chemical weapons and makes no new ones.