As far as I'm aware, metallic lead is not toxic per se, because it
cannot be metabolised. It is the lead compounds, starting with the
various oxides, that are toxic. That having been said, airborne lead
particles could be easily oxidised and sulfided. It should also be
mentioned that lead is not absent from the so-called "cosmic dust" or
micrometeoroids. In fact, scientists use the U:Pb ratio of these to
determine their age and origin. I cannot state the quantities but it is
not insignificant.

One thing that should be realised is that the toxic effects of lead (and
most other elements and compounds) are not linear. There is a threshold,
below which the effect is negligible. Above the threshold, the effect
can follow a law with an exponent of the mass absorbed of anything
between 1 and 2.

Another popular myth is that the toxic effects of lead are irreversible.
Sure, brain cells that have already been destroyed cannot be regenerated
but long term treatment with calcium EDTA and penicillamine will remove
the lead from the system and prevent further damage; at the same time,
it will eliminate all the other symptoms of plumbism (painful
gastrointestinal degradation, reduction of haemoglobin production
causing anaemia, gum disease etc.), which often kick in before severe
mental deterioration.

Brian

MA/NY DDave wrote:
> Hi Again IEEE-Harvey, Gordon, and IPC LF Listservers,
>
> A little add to your CA-Toxic Group, Alcatel-person, Chineese workers tread.
>
> Be careful if they are pulverizing or creating SnPb dust (Is the bottom
> line). By the Way this will probably not be specific to SnPb.
>
> In my early reading of the book I noted previously, from the professors at
> the Univ of Naples (Castellino), it seems that particulate lead is the main
> culprit for lead airborne intoxication and metabolism in organisms. Gordon
> has been focussed on the gas state and it's effects yet maybe it is the
> solid state in small particles that is the difficulty for plants and us
> ANimals. Gordon did note this in his note.
>
> For Airborne Lead there is a base level almost without humans on-board that
> was estimated by a person named Nriagu. It comes from natural particulate
> matter sources (also known as dust). 24.5 x 10*3 tons would be a base level
> without some of man's adds. Due to us all going into the metal age (bronze
> age I think) we have added a pile of Lead and many more metals. I guess my
> point is that even though we have added metals significantly to our
> ecosystem they would be there at some level anyway.
>
> So, Again I don't know the issues behind what you posted or the agenda or
> knowledge of those you noted, yet I wanted to give a little bit more
> ammunition to engage the discussion and continue the learning.
>
>
>
> Yours in Engineering, Dave
> Y i Engr, MA/NY DDave
>
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