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.
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(http://www.startribune.com/local/39693797.html?elr=KArksLckD8EQDUoaEyqyP)
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