> Well Bob sarcasm aside, really all heavy metals are toxic in
> excess of certain concentrations.
That's true of everything, not just heavy metals. Dihydrogen monoxide, for
example, kills an average of 9 people a day in the US.
> However, and its a big one, all
> heavy metals are also necessary for life. All are used in
> metabolic processes in human (animal) organisms.
Are you sure about that ? My understanding is that there are several that
have not (yet) been identified as "essential", including mercury, lead and
cadmium.
But since there is far more zinc in a single penny than an entire case of
motor oil, somehow it seems unlikely it should be banned for that reason.
High concentrations of zinc are also found in many other everyday products,
like sunscreen, diaper rash ointment, calamine lotion and cold lozenges.
Randall
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