Lajos Kamocsay on sun 21 apr 02
Hello,
I've heard about a lot of cases where manganese supposedly has caused =
serious health problems.
So what about clay bodies that contain granular manganese to give a =
speckled effect? Are those safe?
Thanks,
Lajos
Jeff Lawrence on mon 22 apr 02
Jim wrote:
I heard ..this weekend.. that manganese in clay.. is forced into your skin
when you throw.. the rate of turning and pressure of on the clay was said
to
cause it to be very dangerous... Dont know how much of a risk. but it may be
possible..
Vince Pitelka responded:
... This is completely untrue ... There is no danger from manganese
absorption through the skin. And come on now, are ANY of the materials
... in clay "forced into your skin when you throw?"
Jeese, what a loony concept.
Wow Vince, those are strong words! For your info, just last week I forced
some
very sharp bits of gravel into my skin when throwing a local clay...guess
I'll
have to blunge and sieve after all.
On more of a serious note, my impression is that lots of things absorb
through
our skins. That being the case, I think Jim's question is perfectly
appropriate.
Your response, though, seems out of synch with your generally courteous
tone.
I do agree with you wholeheartedly that it is "irresponsible to proliferate
...
misinformation without positively confirming it."
Best regards,
Jeff Lawrence
Snail Scott on mon 22 apr 02
At 09:03 AM 4/21/02 -0700, you wrote:
>I've heard about a lot of cases where manganese supposedly has caused
serious health problems.
>So what about clay bodies that contain granular manganese to give a
speckled effect? Are those safe?
Manganese is not absorbed through the skin.
You still don't want to hang around the kiln
while firing, though. It's the fumes that
you need to avoid.
-Snail
Jim V Brooks on mon 22 apr 02
I heard ..this weekend.. that manganese in clay.. is forced into your skin
when you throw.. the rate of turning and pressure of on the clay was said
to
cause it to be very dangerous... Dont know how much of a risk. but it may be
possible..
Jim in
Denton........
Ababi on mon 22 apr 02
I would like to hear ( to read) from Edouard Bastarache.
You wrote about it last week, I think. I use granular manganese in one
of the claybodies I use, 0.2%. The way I do it is adding the manganeses
to a slurry of clay slip actually. I work lately a lot with paperclay,
so when it is wet, I add the manganese. no hands Electric drill. Ron
Roy offered me once to wash the manganese from the small particles, but
I did not succeed. In general, I think it is a very small amount.
Another question in the spirit of the days, Is this claybody can be
used for food? I know it might be sound a stupid question, but I prefer
to be stupid before rather than after
Ababi Sharon
Kibbutz Shoval- Israel
Glaze addict
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
---------- Original Message ----------
>At 09:03 AM 4/21/02 -0700, you wrote:
>>I've heard about a lot of cases where manganese supposedly has caused
>serious health problems.
>>So what about clay bodies that contain granular manganese to give a
>speckled effect? Are those safe?
>Manganese is not absorbed through the skin.
>You still don't want to hang around the kiln
>while firing, though. It's the fumes that
>you need to avoid.
> -Snail
>________________________________________________________________________
>______
>Send postings to clayart@lsv.ceramics.org
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.
Edouard Bastarache on mon 22 apr 02
> Allo Ababi,
>
> particle size distribution is a critical factor in the case of inhalati=
on
> of occupational dust. Here is a general principal concerning this probl=
em:
>
> "As a general rule, the smaller the diameter of particles, the more
> efficient
> is the pulmonary clearance by the bronchi and acini. The bronchial and
> alveolar retention of particles is the result of two opposing factors,
> deposition and clearance. Retention of dust will be at its peak,
> depending on the nature of dust, for the particles whose diameter
> ranges from 0.5 to 3 microns."
>
> It is difficult for studio potters to afford to have their environment
> studied properly. It will be up to them to decide to use manganese
> clays or not, once properly informed.
>
>
>
>
>
> Manganese & inorganic compounds
>
>
>
> Compounds :
>
> Manganese compounds used by potters are inorganic , like manganese
dioxide,
> oxide
> and manganese carbonate.
>
> Uses :
>
> Metallic applications account for most manganese consumption, with abo=
ut
> 90%
> used in steelmaking.
> Slags coming from old converters, as in the Thomas process in the steel
> industry, can be
> used as fertilizers.
> Certain welding operations require the use of electrodes whose coating=
or
> alloyed core contains manganese.
> The chemical industry uses manganese as a catalyst.
> Permaganates are powerful oxidizers.
>
> Manganese has also different other uses
> -As a coloring material
> - In the manufacture of dry cells
> - In the manufacture of pesticides(Maneb)
> - As food additives for livestock
> - In the composition of fertilizers
> - In pharmaceutical products
> - As siccative for paints
> - In wood preservatives
> - In leather processing
>
>
> Manganese is an essential mineral for humans and animals. It is necessa=
ry
> for
> normal bone formation. It has been estimated that a normal 70-kg man ha=
s a
> total of
> 12mg to 20 mg in his body.
>
> Exposure :
>
> The inorganic compounds do not penetrate the body via skin like some
organic
> compounds, such as certain tricarbonyls.
>
> Inhalation of dust or fume is the major route of entry in occupational
> manganese poisonning. Also inhaled large particles are ingested after
> mucociliary clearance from the lungs. Gastrointestinal absorption is
> generally low (5%). Very few poisonings have occured after ingestion.
>
>
> Acute intoxication ;
> 1-Metal fume fever :
> Inhalation of manganse oxide fumes may cause a flu-like syndrome simila=
r
to
> =AB metal fume fever =BB, treatment is symptomatic.
>
> 2-Chemical pneumonia :
> In the case of severe exposure to fumes or dust of various manganese
salts,
> a severe chemical pneumonia may occur.
>
> 3-Acute intoxication by ingestion :
> Acute intoxication by ingestion rarely occurs and is caused by accident=
al
or
> voluntary ingestion of a manganese salt(as the ingestion of tablets of
> potassium permaganate), this chemical causes massive burns of the
digestive
> tract, oedema of the upper respiratory tract and circulatory collapse.
>
> Chronic intoxication :
>
> The primary target organ of manganese toxicity is the central nervous
> system, particularly the extra-pyramidal system; the lungs may also be
> injured in the case of chronic exposure to manganese.
>
> 1-Central nervous system :
> Neurological symptoms are caused by inhalation of fumes or dusts of
> manganese.
> The extra-pyramidal system is the main target organ of manganese.
> Exposure to heavy concentrations of dusts or fumes for as little as thr=
ee
> months may
> produce the condition, but usually cases develop after 1-3 years of
> exposure.
> In manganese mines where most cases have occurred, the disease has
appeared
> after
> 10 to 20 years of exposure.
> The symptoms may simulate progressive bulbar paralysis, postencephaliti=
c
> Parkinsonism, multiple sclerosis, amyotrophic lateral sclerosis and
> progressive lenticular degeneration (Wilson's disease).
>
> The best way to diagnose, at an early stage, manganese intoxication is
> neurological examination.
> A standardized questionnaire of neurological symptoms is helpful.
>
> Here are some symptoms, among others, to be looked for in chronic
manganese
> intoxication:
> -nervousness
> -irritability
> -memory loss
> -tiredness
> -insomnia
> -muscle weakness
> -muscle pain
> -trembling fingers
> -stiffness of limbs
> -difficulty with fine movements
> -stuttering
> -hoarse voice
> -urinary problems
> -impotence.
>
> At physical examination your doctor should look for signs of an
> extra-pyramidal syndrome at its beginning.
>
> 2-Respiratory tract :
> Pulmonary tissue does not seem to be the critical target organ of
manganese
> during chronic exposure.
> On the other hand, various respiratory symptoms (acute and chronic
> bronchitis, pneumonia, functional changes of the obstructive type) were
> observed among workers exposed chronically to manganese at levels highe=
r
> than those which cause slight neurological disturbances in certain
workers.
>
>
> Reproduction :
>
> Manganese could disturb libido according to certain studies. It was
> demonstrated that a loss of libido and impotence, sometimes preceded b=
y a
> phase of hypersexuality, was observed among subjects suffering from
> manganism.
>
> There are contradictory reports as for the effects of manganese on
> reproduction; however, certain studies showed a reduction in the number=
of
> children fathered by male workers during the time when they were expose=
d
to
> manganese.
>
> In Russia, an excess of spontaneous miscarriages occurred among wives =
of
> workers employed in manganese treatment plants.
>
> Teratogenesis :
>
> No teratogenic action due to manganese has been described in man.
>
> Mutagenesis and carcinogenesis :
>
> The manganese ion has not caused modifications in the DNA among mammals.
>
> In the literature there is no indication suggesting that manganese exer=
ts
a
> cancerogenic action in man. In fact , experimental studies plead rather
> against such an association.
>
> Exposure :
>
> The important thing is your exposure to inorganic manganese, it may va=
ry
if
> you are a pottery factory worker, a teacher, a full-time studio potter =
or
a
> part-time.
> The evaluation of the amount used over a given period of time in clays =
and
> glazes is essential in assessing your exposure in a non-parametric way
i.e.
> without the aid of persons specialized in the field of occupational
hygiene.
> In the wet state, as in moist clays and glazes, these compounds are
> certainly much less hazardous than as dust.
> Pottery factories can financially afford the monitoring of manganese
> exposure but, it is not the same for artists and craftpersons.
>
> The threshold limit value for dusts of manganese metal and inorganic
> compounds actually proposed by the ACGIH is 0.2 mg/m3,as total dust.
>
> Prevention :
>
> So good house keeping of your studio is very important; to do so you ma=
y,
> among other things, use wet processes, or even a vacuum system whose a=
ir
is
> exhausted outside of the workshop.
> Avoidance of processes generating unnecessary dust is also importan. To
> this, we may add work in closed systems and improvement of the general
> ventilation.
> The wearing of an approved dust mask for this kind of hazard is also
> recommended when the level of exposure seems too high.
>
>
>
> Medical surveillance :
>
> 1-Pre-emploiment medical examination :
> It aims at searching for the presence of a neurological and/or pulmonar=
y
> impairment likely to be worsened by exposure to manganese, and it will=
be
> used as reference making it possible to better analyze the results of
> periodical examinations.
>
> Here are some suggested elements;
>
> 1-Complete history taking and physical examination,
> 2-Neurological assessment,
> 3-Spirometry,
> 4-A few psychomotor tests(for instance: evaluation of extremities
tremor-and
> reaction
> (response) time
> 5-Blood and urinary manganese measurements.
>
> 2-Periodical examination :
>
> Its frequency depends on the severity of exposure and on the legislati=
on
in
> force. It consists in seeking, if possible, with the aid of a well
> standardized questionnaire, early symptoms of neuropsychological and
> pulmonary impairment, in repeating the pre-employment examinations and
> comparing them with the latter in order to detect any risk of excessive
> impregnation .
> It is important to practise this comparison, not only at the individual
> level but, also at the level of the group of workers.
>
> Workers exposed to manganese should have a medical examination every 3 =
to
6
> months
> (Shunk, Tanaka and Lieben).
> Experts still differ about the precision of urinary and/or blood
> measurements of manganese as good indicators of exposure and intoxicati=
on
=2E
> Among workers, kept away from their job on a temporary basis, and from
> exposure to
> manganese dioxide, a good correlation was
> observed between urinary and blood levels and the index of cumulative
> exposure, on an individual basis(Lucchini and al.).
> A correlation was also found between these tests and different
> neurobehavioral tests.
>
> But let us not forget that human data are insufficient yet for proposin=
g a
> a blood and/or urinary standard for manganese on an individual basis
>
> Tanaka & Lieben however observed a correlation between the urinary
> excretion and the intensity of exposure, and Japanese authors
> suggested that manganese excretion higher than 40-50 micrograms/liter
> corresponds to a level of exposure where lesions can occur (Horiuchi &
al.)
> .
>
> Often times the only aid to diagnosis is a history of manganese exposur=
e.
>
> I have heard of 2 cases of Parkinson-like syndrome among unskilled work=
ers
> making clays and glazes for a local pottery supplies store (Montreal) t=
hat
> occurred in the 70's before Quebec passed its laws in Occupational Heal=
th
> and Safety
>
> Treatment :
>
> At the beginning of the intoxication, it seems that a chelation treatme=
nt
> with calcium EDTA may favor an improvement of the clinical picture. At =
an
> advanced stage of the intoxication this treatment is ineffective. In th=
is
> case, the treatment is identical to Parkinson's disease (levodopa).The
> usefulness of this treatment is however contoversial.
>
>
>
>
>
> Edouard Bastarache M.D. ( Occupational & Environmental Medicine)
> Author of =AB Substitutions for raw ceramic materials =BB
> edouardb@sorel-tracy.qc.ca
> http://www.sorel-tracy.qc.ca/~edouardb/
>
>
>
> REFERENCES :
> 1-Occupational Medicine, Carl Zenz, last edition.
> 2-Occupational & Environmental Medicine, Joseph LaDou, last edition.
> 3-Chemical Hazards of the Workplace, Proctor & Hughes, last edition.
> 4-Sax's Dangerous Properties of Industrial Materials, Lewis C, last
edition.
> 5-Industrial Chemical Exposure, Lauwerys & Hoet, last edition.
> 6-Toxicologie Industrielle et Intoxications Professionnelles, Lauwerys
> Robert,R.1999
> 7-Encyclopedie Medico-Chirurgicale- Toxicologie-Pathologie Professionne=
lle
> Paris, Lauwerys R, et Roels H., juin 2001.
>
>
>
>
>
>
>
>
>
vince pitelka on mon 22 apr 02
> I heard ..this weekend.. that manganese in clay.. is forced into your
skin
> when you throw.. the rate of turning and pressure of on the clay was said
to
> cause it to be very dangerous... Dont know how much of a risk. but it may
be
> possible..
Jim -
Who in the world did you hear this from? This is completely untrue, and it
is irresponsible to proliferate such misinformation without positively
confirming it. There is no danger from manganese absorption through the
skin. And come on now, are ANY of the materials in clay "forced into your
skin when you throw?" Jeese, what a loony concept.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Brandon Phillips on tue 23 apr 02
I haven't been following this thread very closely so this might not have to
do with anything, but there is an article in the Studio Potter from 98 or 99
about David Shaner. He contracted ALS from breathing too many manganese
fumes. It is a very interesting and powerful article and I recommend
reading it. It is mainly a profile, but there is a lot of information about
how he contracted ALS and cautions about the use of manganese. Also
somewhat recently Steven Hill stopped using manganese in his glazes because
he decided it wasn't worth the risk. Spray booth in a multiple person
studio doesn't always vent everything.
Brandon Phillips
_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp.
Ababi on tue 23 apr 02
This is the time to remind you all of Monnona Rossol's book. I might
spell bad her name,but the book is good, very important book. I do not
read it every day, just when I have a new material. It will teach you
from what to be carful and from what not to.
Both letters are important the potter who thought that by siting in the
same room with manganese, he will be sick: There is no wonder why
Vince was mad, Jim heard stories, perhaps from a friend or a teacher
who thought so or wanted to scare his students. It is good Jim that you
have asked, it sounded " dumb" , it is better to sound dumb than be so.
This is a tolerant list. Yet,some people are a bit less tolerant.
To Vince: It is true that most of our materials are insoluble, but
there are some, like the metal salts sulfates, that are soluble, there
are not directly using in raw clay. I can assure you that if they would
not be harming materials I would add them to my raku claybodies as well
as to the coming saggar&similar tests I am doing.
About my "manganesed" claybody I take the words of Eduard and like
sugar ( in my case) as little as possible and as wet as possible.
Ababi Sharon
Kibbutz Shoval- Israel
Glaze addict
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
---------- Original Message ----------
>> I heard ..this weekend.. that manganese in clay.. is forced into
your
>skin
>> when you throw.. the rate of turning and pressure of on the clay
was
>said
>to
>> cause it to be very dangerous... Dont know how much of a risk. but
it
>may
>be
>> possible..
>Jim -
>Who in the world did you hear this from? This is completely untrue,
>and it
>is irresponsible to proliferate such misinformation without positively
>confirming it. There is no danger from manganese absorption through
the
>skin. And come on now, are ANY of the materials in clay "forced into
>your
>skin when you throw?" Jeese, what a loony concept.
>Best wishes -
>- Vince
>Vince Pitelka
>Appalachian Center for Crafts
>Tennessee Technological University
>1560 Craft Center Drive, Smithville TN 37166
>Home - vpitelka@dtccom.net
>615/597-5376
>Work - wpitelka@tntech.edu
>615/597-6801 ext. 111, fax 615/597-6803
>http://www.craftcenter.tntech.edu/
>_______________________________________________________________________
_
>______
>Send postings to clayart@lsv.ceramics.org
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.
Dan Bowen on tue 23 apr 02
On Mon, 22 Apr 2002 20:15:59 -0500, vince pitelka
wrote:
>> I heard ..this weekend.. that manganese in clay.. is forced into your
>skin
>Who in the world did you hear this from? This is completely untrue, and it
>is irresponsible to proliferate such misinformation without positively
>confirming it. There is no danger from manganese absorption through the
>skin. And come on now, are ANY of the materials in clay "forced into your
>skin when you throw?" Jeese, what a loony concept.
>Best wishes -
>- Vince
>
>Vince Pitelka
There are no stupid questions. This person didn't know and asked this
list. I am here to help and learn from all levels of skill and experience.
I respect your skill and experience but not your attitude here
Dan Bowen
Eastville Pottery
Edouard Bastarache on tue 23 apr 02
Right on, Vince
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
----- Original Message -----
From: vince pitelka
To:
Sent: Monday, April 22, 2002 9:15 PM
Subject: Re: manganese in clay bodies
> > I heard ..this weekend.. that manganese in clay.. is forced into your
> skin
> > when you throw.. the rate of turning and pressure of on the clay was
said
> to
> > cause it to be very dangerous... Dont know how much of a risk. but it
may
> be
> > possible..
>
> Jim -
> Who in the world did you hear this from? This is completely untrue, and
it
> is irresponsible to proliferate such misinformation without positively
> confirming it. There is no danger from manganese absorption through the
> skin. And come on now, are ANY of the materials in clay "forced into your
> skin when you throw?" Jeese, what a loony concept.
> Best wishes -
> - Vince
>
> Vince Pitelka
> Appalachian Center for Crafts
> Tennessee Technological University
> 1560 Craft Center Drive, Smithville TN 37166
> Home - vpitelka@dtccom.net
> 615/597-5376
> Work - wpitelka@tntech.edu
> 615/597-6801 ext. 111, fax 615/597-6803
> http://www.craftcenter.tntech.edu/
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Jennifer Assinck on tue 23 apr 02
I hope that Jim and others, myself included, continue to ask questions if we
are not sure about something. I, myself, have read a lot about pottery, but
I would be the last to say I know everything. I am bound to make mistakes,
and it will then be an excellent opportunity for those who do know better to
take the opportunity to correct us. This correction will also be in the
archives with our misinformation.
What I do not appreciate is the tone of some responders who belittle either
the correspondent or his/her source. Can we give the benefit of doubt that
the source did not intentionally lie?
I know first hand, the temptation to respond privately to a query, lest I be
blasted. However, I encourage all of us to grit our teeth and reply to the
list so that others can learn by our mistakes. We probably are not the only
ones who are mistaken.
Regards,
Jennifer Assinck
Newmarket, Ontario, Canada
>
> From: Jeff Lawrence
> Date: 2002/04/23 Tue AM 01:44:03 EST
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: manganese in clay bodies
>
> Jim wrote:
> I heard ..this weekend.. that manganese in clay.. is forced into your
skin
> when you throw.. the rate of turning and pressure of on the clay was said
> to
> cause it to be very dangerous... Dont know how much of a risk. but it may
be
> possible..
>
> Vince Pitelka responded:
> ... This is completely untrue ... There is no danger from manganese
> absorption through the skin. And come on now, are ANY of the materials
> ... in clay "forced into your skin when you throw?"
> Jeese, what a loony concept.
>
>
>
> Wow Vince, those are strong words! For your info, just last week I forced
> some
> very sharp bits of gravel into my skin when throwing a local clay...guess
> I'll
> have to blunge and sieve after all.
>
> On more of a serious note, my impression is that lots of things absorb
> through
> our skins. That being the case, I think Jim's question is perfectly
> appropriate.
> Your response, though, seems out of synch with your generally courteous
> tone.
>
> I do agree with you wholeheartedly that it is "irresponsible to
proliferate
> ...
> misinformation without positively confirming it."
>
>
> Best regards,
> Jeff Lawrence
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
>
Clay Coordinator on wed 24 apr 02
Jeff,
Manganese may not be absorbed into your hands but it may get into any cuts
you have. Or cuts you may get while throwing.( When the metal rib slips.)
Surely it gets under your fingernails and when you eat without getting it
all off, then it is in your stomach.
Also, as we all know, the spinning wheel throws clay everywhere. Splashes it
up in your face, in your eyes, etc. Therefore you are getting manganese all
over the studio, your body and your clothes. Then you put those clothes in
your washer. Now it is in your house, on your families clothes, etc. (This
is exactly what happened in Libby Montana at the vermiculite factory. Family
members who never when to the plant got aspestosis.)
Now you have manganese everywhere. If that worth it?
I hope so.
Thanks,
John Britt
Penland Clay
Snail Scott on thu 25 apr 02
At 09:47 AM 4/24/02 -0500, you wrote:
>Manganese may not be absorbed into your hands but it may get into any cuts
>you have. Or cuts you may get while throwing.( When the metal rib slips.)
>Surely it gets under your fingernails and when you eat without getting it
>all off, then it is in your stomach.
Edouard, who is a professional in this field, had told us
MANY times that the primary hazard is from inhalation of
FUMES. If some particles of manganese did get imbedded
in your skin, almost none would be absorbed. Even if you
managed to swallowed some, only 5% of that will reach your
brain, the organ that is most affected by manganese.
>...Then you put those clothes in
>your washer. Now it is in your house, on your families clothes, etc. (This
>is exactly what happened in Libby Montana at the vermiculite factory.
Manganese is NOT vermiculite!!! The hazards of inhaling
particles of vermiculite are very real, but they are not
the same hazards as for manganese. You cannot extrapolate
form one to the other - they are very different materials.
-Snail
Clay Coordinator on fri 26 apr 02
Scott,
As Edouard has pointed out, the primary hazard is from inhalation of fumes.
But that does not mean that there are not secondary hazards. And neither of
these should be trivialized.
There is also the factor of cummulative effects. If, as you say, only 5%
will reach your brain, then consider if you injested on average, one-tenth
of a gram a day. If you worked 6 days a week as many potters do, that means
you would get 1.5 grams in your brain in a year. In 20 years, you would get
30 grams in your brain. What that would do to you, I do not know, but I am
sure that it would not be referred to as "only" 5% at that point.
In the case of vermiculite, surely they are not the same material. But the
point is that the plant officials assured everyone that there was no
problem. That is until it was discovered that there was a problem. Then
there is terrible regret. Now it is easy to say the problems with
vermiculite are real. They are only real when the effects are discovered,
but then it is too late for caution.
The problem with a lot of "what we know" is that it changes. Tomorrow it
may be found to be completely harmless, or it may be found to be extremely
toxic. But we really do not know for sure. We do not know all the effects
of long term exposure to manganese. Nor do we know the long term effects of
being exposed to multiple metals simeltaneously. (manganese, barium, lead,
copper, nickle, etc)
That is why you should always exercise caution when working with these types
of chemicals and advocating there safe usage.
Thanks,
John Britt
Penland Clay
Snail wrote:
Date: Thu, 25 Apr 2002 10:23:55 -0700
From: Snail Scott
Subject: Re: manganese in clay bodies
At 09:47 AM 4/24/02 -0500, you wrote:
>Manganese may not be absorbed into your hands but it may get into any cuts
>you have. Or cuts you may get while throwing.( When the metal rib slips.)
>Surely it gets under your fingernails and when you eat without getting it
>all off, then it is in your stomach.
Edouard, who is a professional in this field, had told us
MANY times that the primary hazard is from inhalation of
FUMES. If some particles of manganese did get imbedded
in your skin, almost none would be absorbed. Even if you
managed to swallowed some, only 5% of that will reach your
brain, the organ that is most affected by manganese.
>...Then you put those clothes in
>your washer. Now it is in your house, on your families clothes, etc. (This
>is exactly what happened in Libby Montana at the vermiculite factory.
Manganese is NOT vermiculite!!! The hazards of inhaling
particles of vermiculite are very real, but they are not
the same hazards as for manganese. You cannot extrapolate
form one to the other - they are very different materials.
-Snail
Edouard Bastarache on sat 27 apr 02
Hello John,
The recommended daily allowance of manganese for
adults over 18 is 2.0-5.0 mg/day.
Mn is the least toxic of essential metals.
The highest concentrations of Mn are found (in descending order)
in bone marrow, brain, kidney, pancreas and liver.
Nearly 40% of the body's Mn pool is concentrated in the bone
marrow.
We must not forget that manganese is also excreted, not only ingested.
Whole body half-life is slowest among normal individuals and fastest
among those who are heavily exposed, it varies from 15.0 to 37.5 days.
Mn homeostasis is strictly regulated in the human body, such that rates
of excretion always exceed absorption. Therefore, long-term
accumulation is minimal in aging humans.
So, do not confuse manganese with coffee in your shop
first thing in the morning .
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
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