Mainland Japan did not see any ground fighting, only firebombing and the two atomic bombs. Therefore, one would not expect the locals to have been exposed to the results of infantry firing thousands and thousands of bullets.
By the time the frontline reached Germany, the war was almost over.
Yes, but the volume has been way smaller before, until the advent of automated weapon in the 20 th century.
Some really early ones used stones or wooden bolts but firearms hadn't really taken off then and they fell into obscurity for a reason.
Before they also had more common /even worse/ practices like casting bullets by campfire for better fit and logistics than early manufacturing.
Even in inhabited parts of France they have an “iron harvest” as plows continue to turn up unexploded ordinance.
Has there been a study showing this correlation? As far as I know, countries that were shattered in World War 2, like Japan and Germany, are less violent on average, than the US. And note: the mainland continental US has been relatively at peace, and has not had any major domestic hostilities since 1865.
Also, have bullets always (historically) had lead? Or is this something that only newer ammo (since WWII) have?