[chubot]

I don't really know the history of lead, but I suspect it illustrates the point.

There are no traditional foods with lead in them, because people who ate lead would have died, ensuring that the custom didn't survive.

However lead paint was a relatively new thing. People didn't have painted walls for thousands of years. It was used for awhile (not sure how long), and then the test of time figured out that it was poisonous.

Is there some history you know of where the test of time didn't work? It's almost tautological to be honest. (And tautological does not mean "untrue" :) )

Lead might have been "bad" by modern standards in the past, but there were also hundreds of other things that were worse for mortality, so maybe lead use in certain applications just got noticed in the last century or so.