If so, how did they explain radiation poisoning?
Check this answer from /u/restricteddata
https://www.reddit.com/r/AskHistorians/comments/401k3n/is_there_historical_reference_to_radiation_or/cyrxaif/
And this one from /u/poob1x
https://www.reddit.com/r/AskHistorians/comments/72da2j/did_people_from_the_middle_ages_or_earlier_come/dni0af9/