> If it killed large numbers of the people that took it, they'd have stopped using it.
Eeeehh not necessarily, it just needs to be better than not using it or not being trivially linked to the stuff.
Romans used lead as sweetener both indirectly (making defrutum and sapa in lead pot which they'd found gave them a sweeter taste than brass — because of the lead leeching into the boil) and directly after discovering the extraction of lead acetate from litharge using vinegar. And lead acetate remained in wide use as a sweetener well into the european middle-ages as the only alternate sweetener was honey which wasn't that common. Sugarcane sugar imports from India only started after crusaders brought sugar home from raiding sugar caravans in the middle-east, followed by the triangular trade's massive sugarcane exploitations in the new world — and even then it would remain a luxury in most of europe until the 18th century.
> elemental mercury, radium, and phosphorous were also used as medicines even when they did not have redeeming medicinal uses.
Well, mercury is a fairly effective antibacterial agent, it's just that we don't use it much anymore because it's also very toxic to humans. I think it still does have some (limited) medical applications.
Eeeehh not necessarily, it just needs to be better than not using it or not being trivially linked to the stuff.
Romans used lead as sweetener both indirectly (making defrutum and sapa in lead pot which they'd found gave them a sweeter taste than brass — because of the lead leeching into the boil) and directly after discovering the extraction of lead acetate from litharge using vinegar. And lead acetate remained in wide use as a sweetener well into the european middle-ages as the only alternate sweetener was honey which wasn't that common. Sugarcane sugar imports from India only started after crusaders brought sugar home from raiding sugar caravans in the middle-east, followed by the triangular trade's massive sugarcane exploitations in the new world — and even then it would remain a luxury in most of europe until the 18th century.