nightjar wrote:
A few years ago, some scientists ran tests on the Holland and Holland
shooting ground - an area that has been peppered with lead for a couple of
centuries or so. They found that the lead had no significant effect on the
toxicity of the soil, although the amount of lead shot made recovering it an
economic proposition.

Humph. Lead is very occasionally found "native". Other metals
similarly found are silver, copper, mercury, gold, etc. IIRC.