Did a Google search on lead exposure from soldering. Came up with this MSDS
sheet (http://www.frymetals.com/pdf_uploads/MSDS%203.5.PDF), which suggests
that resin vapors are the main problem, saying that lead fumes don't form
until 700 degrees Fahrenheit. The following websites suggests that these
fumes contain lead oxides (http://www.sentryair.com/solder%20fume.htm).
Haven't found definitive sources yet though....
In pictures I've seen of dismantling operations in China and India, workers
are holding circuit boards over little coal stoves. I presume an important
question w.r.t. lead exposure is then what temperature do those stoves heat
the solder to. Don't know the answer to that one though...
Best, Eric
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Eric Williams
United Nations University
Environment and Sustainable Development Programme
IT and Environment Project
http://www.it-environment.org
53-70 Jingumae 5-chome Shibuya-ku Tokyo, Japan
Phone: 81-3-5467-1352 Fax: 81-3-3406-7346
------------------------------------------------------------------------
> -----Original Message-----
> From: Brian Ellis [mailto:[log in to unmask]]
> Sent: Sunday, July 18, 2004 4:50 PM
> To: [log in to unmask]
> Subject: Re: [LF] "lead vapors" myth
>
> 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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