something got me thinking about arsenic and damp moldy dwellings. here is a fun mystery from history involving someone you probably heard of in school. it's maybe worth considering that even though arsenic is sort of out of fashion these days, it is perhaps notable that it was still used in wood preservatives in the US until pretty recently(about a decade ago, and maybe it is still available some places, idk):

https://edu.rsc.org/feature/poisoned-or-not-napoleons-death/3007400.article
Poisoned or not? Napoleon’s death - 1 November 2010
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...Focusing upon his living conditions on Saint Helena, we note that his room was decorated with wallpapers that had a pattern printed with a pigment known as Scheele’s Green, a green insoluble compound copper arsenite (CuHAsO3).  While on dry wallpaper Scheele’s Green is not a problem. However, if the wallpaper becomes damp – and Saint Helena is a particularly damp place – the compound reacts and produces cacodyl (trimethyl arsenic, As(CH3)3) and a serious problem arises. For a start, cacodyl is volatile so it evaporates from the wallpaper and fills the room, and unlike the solid pigment copper arsenite cacodyl is much more toxic. Any occupant that spent any length of time in the affected room would inhale the cacodyl and absorb high doses of a treacherously poisonous compound.   

It may well be that Napoleon did die of stomach cancer but suggestions of arsenic poisoning are plausible. However, if arsenic poisoning was the culprit it was highly likely to be unintentional and due to inhalation and absorption of cacodyl from the wallpaper. Of course, if Napoleon did die from stomach cancer the cancer could also have been caused by arsenic since arsenic and its compounds are carcinogenic... 
"""

https://www.pbs.org/newshour/health/how-napoleons-death-in-exile-became-a-controversial-mystery
How Napoleon’s death in exile became a controversial mystery - Aug 15, 2022
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...Decades later, the chemists J. Thomas Hindmarch and John Savory wrote a rebuttal to the claims of arsenic poisoning. It is important to note, they reminded their readers, that in the bad old days of medicine—when bleeding and cupping were still major treatment modalities— arsenic was a common, if ill-advised medication, often bottled in the form of a tonic known as Fowler’s solution. It was also widely used in rodenticides, insecticides, clothing dyes and “even candy wrappers.” Moreover, French aristocrats, including Napoleon, wore arsenic-based face and hair powder. There also may have been arsenic in the water supply, the wallpaper covering Napoleon’s bed chamber, in the coal smoke heating his chambers, and post-mortem exposure because of the arsenic soil content covering his coffin, when he was still buried on St. Helena before being brought back to Paris. And to make matters more confusing, there was also the 19th-century practice of preserving locks of hair in arsenical solutions and hair powders...
"""

further reading: 
https://www.napoleon.org/en/history-of-the-two-empires/articles/the-poisoning-of-napoleon-an-update/

https://www.amnh.org/explore/news-blogs/was-napoleon-poisoned

https://en.wikipedia.org/wiki/Cacodyl

https://en.wikipedia.org/wiki/Trimethylarsine

https://en.wikipedia.org/wiki/Arsine