Dave Finkelnburg on tue 23 apr 02
Hi All,
Interesting questions, comments regarding manganese and how it is
dangerous to us. I am sure Dr. Edouard Bastarache will have a knowledgeable
comment.
Scientists who study how chemicals are dangerous to us often classify
them according to the pathways in which the chemicals get into our body. In
this sense, the word "pathway" is a powerful term.
The primary pathway we need to be concerned about with manganese is
INHALATION. The manganese becomes a vapor, a gas, when heated hot enough in
the kiln, and we can then inhale it. I suspect our bodies care little
whether the inhalable manganese comes from the glaze or the clay body.
While less of a problem, manganese dust can also be inhaled and is harmful.
INGESTION is another pathway by which manganese can hurt us, but few of
us eat much of it. Keeping it away from small children, however, is
extremely important!
ABSORPTION of manganese through the skin is not usually a major pathway
for us to be exposed to dangerous amounts of manganese. There are chemicals
in the pottery, typically water soluble, which we can absorb through the
skin, but manganese, either in the clay body or glaze is not one.
So what's the bottom line? IF you use manganese in any form, protect
your lungs! Use an excellent dust respirator when handling MnO2 dry. Vent
your kiln very, very well.
Respectfully,
Dave Finkelnburg
Edouard Bastarache on tue 23 apr 02
Hello Dave,
It does nor skin absorbs.
Gastrointestinal absorption is generally low (5%).
Bio-availability is also a critical factor in toxicology.
It the case of manganese it has to reach the brain,
so, approximately only 5% of the ingested amount
may reach this target organ.
In clays in is used in 60-80 mesh size (rather large particles).
According to my counsel/suggestion, Tony Hansen has developed
clays with specks without the use of manganese, using an
innocuous material.
I will leave to him to comment because he did the tests
and it is his own "industrial" secret.
Later,
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
John Baymore on sun 28 apr 02
In clays it is used in 60-80 mesh size (rather large particles).
This thought assumes that the granular manganese material is supplied int=
o
the body without all the "fines" that typically accompany such materials.=
=
If the fines are present...... then that (likely) respirable fraction
becomes part of the clay body.... and hence somewhat contaminates the dry=
claybody dust that will tend to pervade the studio environment of all but=
the most fastidious ceramist.
Best,
..............................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752 (s)
800-900-1110 (s)
JohnBaymore.com
JBaymore@compuserve.com
"DATES SET: Earth, Water, and Fire Noborigama Woodfiring Workshop Augu=
st
16-25, 2002"
Clay Coordinator on mon 29 apr 02
Vince,
I was illustrating that the term "only" in Snails post quickly becomes large
over time.(please refer to original post.)
I am not presenting myself as an expert in the field of toxicology. But I
can read OSHA reports and I do know that there are differing opinions among
experts. We could ask Monona her opinion or any number of other experts,
and I am sure we would have that many opinions.
Also, experts only know what studies have found. They don't know what
future studies will find. The the interaction of chemicals in our bodies and
the cumulative effects are not completely understood.
Until that day caution is always the best course when dealing with these
chemicals. I do not believe that a position of minimizing exposure to
hazards is irresponsible.
Thanks,
John Britt
Penland
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