If you had just spent 5-10mins watching excerpts from above timestamps you would have seen interviews with workers doing such jobs from rural America/Canada/Spain/France/etc., sleazeball CEOs of sleazy companies taking these sort of contracts from Facebook/etc. and then farming it off to poorer parts of the World in Asia/Africa/South America/etc., psychologists who study and warn of the very real dangers of such a job etc.
So before asking for more data, start with the one i have already given you. The psychological harm caused by repeated exposure to graphic imagery is well studied; AI image annotation is one subset of that.
Here is a detailed article; The Ghosts in the Machine: Inside AI’s Hidden Human Trauma - https://www.thebrink.me/the-ghosts-in-the-machine-inside-ai-...