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February 2009

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Subject:
From:
Bev Christian <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Bev Christian <[log in to unmask]>
Date:
Tue, 17 Feb 2009 12:37:07 -0500
Content-Type:
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text/plain (252 lines)
Denny,
There has never been a case of lead fumes in any normal soldering
process - the temperatures are too low. In my lead pollution
presentation I have added in a slide that compares the vapor pressure of
mercury to that of lead.  The difference is quite stark.  There is no
currently available reasonable method that I know of to detect the
infinitesimal amount of elemental vaporized lead over a soldering iron
or solder pot set at any temperature that would ever be seen by a
circuit pack during manufacturing or rework.  

It is a different story regarding lead oxide negligently drossed off of
a wave solder pot.
Bev
RIM

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Fjelstad
Sent: Tuesday, February 17, 2009 12:25 PM
To: [log in to unmask]
Subject: Re: [TN] Leadfree has gone too far.

Hi Denny
 
We need Cr3 in our diets as an aid in glucose metabolism,  the same
case, 
cannot be made for lead. As for the lead industry lack or response, with
lead 
in solder representing less than 0.5% of all lead used annually, there
was  not 
enough there to for them to worry about, on the other hand the increased
use  
of tin was very beneficial to that industry and would provide ample
incentive 
to  have lead in solder blackballed, whether or not they actually ever
did  
so is known only for certain by the leaders of tin industry.  ( with
the word 
leaders obviously pronounced "leeders" not "leders"...  ;-)  

Cheers, 
Joe
 
 
In a message dated 2/17/2009 8:30:57 A.M. Pacific Standard Time, DDFRITZ

writes:

My  ancient chemical engineering degree stirs me to comment on this
thread 
(always  dangerous)

The main culprit in lead uptake by all animals is the  chemistry of the
lead. 
 Oxidized state lead - lead oxide left from  burning leaded gasoline, or
lead 
chromate from the various yellow, orange and  red lead pigments in
paints is 
very easy for the blood to pick up.   Tetraethyl lead for leaded gas is 
horribly toxic to all animals because it is  so very easy to absorb
(remember 
washing grease off your hands with gasoline  before about 1970?).  That
ionized lead 
is still out there in the paint  chips or soil surface layer, as Joe
points 
out.  

Elemental lead  is pretty innocuous to animals (carrying a bullet from
the 
war, etc.) except  for one nice way to create ionic lead in the body -
the 
stomach acid that  works on elemental lead when eaten.  That is not very
fast, but 
it is  steady  - in the case where the lead remains in the stomach -
ducks 
whose  gizzards grind shot or sinkers against sand and gravel in
digestion, 
someone's  cow where the weight stayed at the bottom of one of the four
stomachs, 
or  sadly, some super cheap lead trinkets that lodged in small child
stomachs 
or  intestines.  Don't forget the cheap yellow and orange paint on toys
- we 
covered that before.   

I think years ago on TechNet, we  discussed how much lead is absorbed
from 
lead solder assembly - I can't  remember a single case of significant
lead fumes 
- am I wrong?  Sanity  says to ventilate - the flux smell can get to
you.  I 
hear about lead  exposure from "roasting circuit boards on an open fire"
in 
third world  countries.  How much of that is no hand washing instead of

breathing?  How much from using the same pot for stir fry as for
roasting  boards?

How did we get the environmentalists to limit chrome  controls to Chrome
+6?  
A better marketing job by the "Chrome Industry  Council"?.  Lawmakers
still 
wanted their shiny cars and plumbing  fixtures?  The stainless steel
folks 
drove some sanity?  Guess there  is no "Lead Industry Council" to stand
up for 
their product.  

My  simple answer would be to restrict lead where it is ionic (done now 
through  these bans), AND elemental lead where it can easily be ingested
- shotgun  
shot, sadly for me fishing sinkers, and anything say smaller than 2
ounces.  
And, in my opinion, lead in solder for circuit boards is safe -  who
eats 
them?  I think IPC helped get circuit boards in toys exempted  from this

legislation, right?

What da ya think?
Denny  Fritz


-----Original Message-----
From: Joe Fjelstad  <[log in to unmask]>
To: [log in to unmask]
Sent: Tue, 17 Feb 2009  10:49 am
Subject: Re: [TN] Leadfree has gone too far.


Unfortunately, the road to perdition is paved with good intentions  and
it's  
sad to say, but common sense is not so common anymore. I am  confident
that 
 there are many folks out there paving the road who are applauding  this

news.  
 So it goes...
  
 Joe
  
 PS Steve's observations are on target. The lead acetate (aka lead
sugar) in 
 paint is what make eating paint chips attractive to children. The  
elimination 
 of lead from gasoline and paint were two of the best solutions  to
reducing 
 lead in the environment. Others have  followed wanting to build on that

legacy 
 using assertion without proof and  conjecture rather that science or
data. 
For 
 the record, the  discovery of the fall out from lead in gasoline came
when 
 there was a study  done to see if there was risk from using tin-lead
solder 
for 
 canned food  lids which was shown to account for a smaller percentage
than 
 expected. The "no  effect" limit for lead consumption is 3 mg per
person per 
 
 week  according to "Encyclopaedia of Environmental  Agricultural
Pollution 
and 
 Its Control" By G.R. Chhatwal.  in Chapter 21 "The Impact of Inorganic
Spoil 
 Pollutants on Consumers" (but it  was not recommended ;-) 
  
 He also pointed out lead paint  licking by animals as one of the prime 
 sources and reported in the  book that higher calcium intake
significantly 
 reduced 
 lead  uptake/absorption. Interestingly, most of the lead comes from the

soil 
 attached to the roots eaten by grazing animals. Given the fact  that a
micro 
 thin layer of lead has been deposited all over the land  over for the
half 
 century that leaded gasoline was most common,  it reinforces the
validity of 
the 
 
 ban (though it is  still in use for some aviation fuel and in some less

 developed countries I  believe)
  
  
  
  
 In a message dated 2/17/2009 6:12:25 A.M. Pacific Standard Time,  
 [log in to unmask] (mailto:[log in to unmask])  writes:
 
 The kid in the  picture might accidentally eat the battery terminals. I
 just had to  laugh.
 
 
_http://www.startribune.com/local/39693797.html?elr=KArksLckD8EQDUoaEyqy
P_ 
(http://www.startribune.com/local/39693797.html?elr=KArksLckD8EQDUoaEyqy
P) 
 4O:DW3ckUiD3aPc:_Yyc:aULPQL7PQLanchO7DiUss
 



 
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