> Natural certainly. But still hazardous. As I'm sure you are well aware,
> lead is a very nasty substance indeed once it gets concentrated in
> unnatural amounts. And compounds can in some instances be worse than the
> pure substance if they increase volatility or solubility.

'Concentrated' lead as in, natural lead lode, mixed with sulfur and silver
and arsenic and antimony and mercury, washed by umpteen gallons of water
per minute in its underground deposit for the past 3 or 4 millions of
years at least, or do you mean 95% pure lead, as in 20-gram fishing
weights ?

If you want to know what's going to happen in the landfills look up
stannic organometallic compounds. Compare the MSDS sheets of, for example,
tetraethyl lead (a banned lead compound), and a stannic organometallic
compound (tin will be left alone to replace lead when that guideline goes
through) [*].  And the funny part is, tin is more reactive than lead so
from an alloy like 60/40 solder, tin organometallic compounds are more
readily formed than lead compounds, when it is exposed to reactive
substances. So by removing the lead, the tin stays. As before, or as it
stays now. It would make more sense to ban tin instead of lead in printed
circuit boards ?!

lead:

http://ptcl.chem.ox.ac.uk/MSDS/LE/lead.html

now for some nice, safe, environmentally compatible tin compounds (tin
will remain in use after they forbid lead, and it is reactive, so there is
no shortage of compounds formed very easily):

http://physchem.ox.ac.uk/MSDS/TI/tin_IV_chloride.html
http://physchem.ox.ac.uk/MSDS/TI/tin_II_chloride_dihydrate.html
http://physchem.ox.ac.uk/MSDS/TI/tin_II_fluoride.html
http://physchem.ox.ac.uk/MSDS/TI/tin_II_oxalate.html
http://physchem.ox.ac.uk/MSDS/TI/tin_IV_chloride.html
http://physchem.ox.ac.uk/MSDS/TI/tin_IV_oxide.html
http://physchem.ox.ac.uk/MSDS/TI/tin_oxalate.html

Notice the skull-and-bones at the top of almost each page.

I could not find a single Sn compound that is not poisonous or harmful,
although the bare metal is not supposed to be toxic (neither is lead
btw.). Maybe the Romans doomed their civilisation by perusing those Pb
cups but they could have gotten there much faster by using straight Sn
cups I think.

[*] organometallic compunds are almost all poisons.

Peter

(note that I am not a chemist)

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