There were arsenic eaters in Styria

From the English Wikipedia:

https://en.wikipedia.org/wiki/Arsenic_trioxide?wprov=sfla1

In Austria, there lived the so-called “arsenic eaters of Styria”, who ingested doses far beyond the lethal dose of arsenic trioxide without any apparent harm. Arsenic is thought to enable strenuous work at high altitudes, e.g. in the Alps."

(The German Wikipedia has a whole article on this: https://de.wikipedia.org/wiki/Arsenikesser?wprov=sfla1)