amy parker on thu 14 may 98
My husband found an article about manganese in the June 1998 Scientific
American, p. 35 "Running on MMT?", under Environmental Policy, author Krista
McKinsey. Here are a few excerpts:
The auto industry despises it, the petroleum industry is avoiding it, the U.S.
government was forced to legalize it, and animal studies sugest that its key
ingredient can damage health. Yet MMT, a fuel additive that increases octane
and reduces oxide emissions, is marketed worldwide as safe, effective, and
efficient. Its manufacturer, Ethyl Corporation, based in Richmond, VA, is so
sure of MMT that it is now suing the Canadian government, which in April 1997
banned for health concerns the import and interprovince trade of MMT, after 20
years of use.
At issue is MMT's main component, manganese. Small amounts in the diet are
beneficial and necessary, and large amounts pose no threat because the liver
can rid the body of any excess. BUT INHALED MANGANESE IS A DIFFERENT STORY
(My emphasis). Epidemiologist Ellen K. Silbergeld of the University of Maryland
points to studies of monkeys that show the dose reaching the brain is
consistently higher than when ingested and can cause neurological disorders
similiar to Parkinson's disease. She cites studies suggesting that airborne
metals can travel up the olfactory nerve to the brain. The fear is that vapors
of MMT-enhanced gasoline - which does not have to be labeled in the U.S. -
might enter the atmosphere. (....snip....)
Commuting via the subway, ..., where the steel tracks are 12 percent manganese,
has a much greater impact than MMT usage does. "Therefore is is virtually
impossible to design a meaningful experiment to determine the long-term effects
to low-level manganese from MMT because humans are already exposed to
significant and variable amounts of manganese throughout their lives in air,
food, water, and soil." (....snip....)
The case mirrors the controversy over another fuel additive: tetraethyl lead.
Like MMT, it was known to be harmless at low doses when it was approved 75
years
ago under pressure from its maker, also Ethyl. As it turned out, the increased
use of lead in gasoline, combined with the use of lead in paints, was associated
with severe neurological disorders, particularly in children. (....snip....)
"Why unleash another toxin into the atmosphere only to find out that it causes
neurodegenerative diseases many years from now?"
end of excerpt.
Not that I am any kind of expert in the area, but from reading this I gather
that the primary concern to us potters should be the breathing of the dust
from our clay or glazes and not the leaching of the element out of the glaze.
I am using up the last of the manganese clay I have on hand this morning,
OUTSIDE where I can hose it all down, and am going to bury the scraps.
amy parker Lithonia, GA
amyp@sd-software.com
Paul Lewing on sat 16 may 98
Amy,
Very interesting article. Thanks very much for posting it. To add to
the conclusion that the danger from manganese was mostly from inhaling
it, I might add that when I spoke to David Shaner last fall and he
told me he thinks his terrible health problems were from mnaganese
ingestion, that he believes the way he ingested the Mn was from
inhaling it as fumes during firing. I have no idea how volatile it
is, but the glaze he was working with so much had huge amounts of Mn
in it, much more than could reasonably be expected to be dissolved in
the melt.
This also supports my contention that, while concern for the health of
our customers is great, the greater danger from all these potentially
toxic materials is to us.
Paul Lewing, Seattle
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